Part 1: What is Evolution?
Part 2: Evolutionary Mechanisms
Part 3: Evolution and Time
Part 4: Adaptation, Radiation, and Speciation
Part 5: Survival of the Fittest
Part 6: Sexual Selection
Part 7: Coevolution
Part 8: Additional Factors that Influence Pace of Evolutionary Change
Part 9: Intermediate Forms and “Missing Links”
Part 10: Evolution and new (Genetic) Information
Part 11: Evolution is only a Theory and not a Fact?
Part 12: Evolution and Probabilities
Part 13: Evolution, Morals, and the Purpose of Life
Part 14: The Limitations of Evolution and why Nothing is Perfect
Part 15: Micro vs. Macro – Different Levels of Evolution, same Principles
Part 16: Evolution and the Homo sapiens
Part 17: Why Design doesn’t Require a Designer
Part 18: Evolution, Superstition, and the Supernatural
Part 19: The Weaknesses of Science
Part 20: The Nature vs. Nurture Debate
Sources referred to in the text as superscript:
1: Futuyma. Evolution. Sunderland: Sinauer Associates, 2005.
2: Berg, Tymoczko, and Stryer. Biochemistry. New York: Freeman and Company, 2002.
3: Stanford, Allen, and Antón. Biological Anthropology. Upper Saddle River: Pearson Education, 2006.
Evolution – Facts, Myths, and Misunderstandings
Part 19: The Weaknesses of Science
After 18 parts on the beauty of science it is only fair to consider its weaknesses which cause it to be less true and genuine than it could be.
No progress without new dangers?
First of all, even if not intended, science has brought forth ever new techniques and methods that were utilized in order to harm humans or living beings in general. We have reached a stage where our technological achievements poison the water that we drink, pollute the air that we breathe, ruin the soil that we need to grow our food, or kill members of our own species. Alfred Nobel certainly didn’t vision suicide bombers blowing themselves up in the middle of a crowded place when he invented dynamite. When Allesandro Volta worked on understanding and using electricity, he probably didn’t do so because he wanted to see other humans die on an electric chair. When Charles Darwin published “On The Origin of Species”, he never intended that his ideas would later be used for the sick propaganda of so called Social Darwinists. Sometimes it seems that any scientific achievement that is supposed to benefit mankind is inevitably linked to the potential of misusing it for evil purposes. It is the ultimate responsibility of science to be aware of that. Some might be better left undiscovered. The quest for ultimate knowledge should come to a halt when the risks of harming human beings become too high. The problem of course is that many problems or disadvantages are only recognized after an achievement has been reached. Nevertheless, as with medicine, everything a scientist does should be guided by the principle of helping human beings and nature.
This point might differ in accordance to the country one works in, but in Germany most researchers spend a considerable amount of time and effort on acquiring funds. As a result, the researcher has to face a certain type of pressure. The institution or person funding your project expects results sooner or later. Without them, the support might come to an end. In the worst case, the continuation of your carrier might be at stake. Hence, some studies might be “enhanced” in order to make the results look more promising. It doesn’t even mean that someone would lie. It rather means that things could be bent in a desired way, neglecting some scientific principles such as objectivity and reluctance.
Some extreme cases of inadequate reluctance are especially known from some paleontological discoveries. If a new promising fossil is discovered, some scientists might make their findings (and their conclusions) public before enough reliable studies have been conducted. The major problem with this kind of rash behavior is that if later studies prove the researchers wrong, it is not only their reputation that suffers but also the reputation of science as a whole. After all, rushed interpretations and the following corrections might cause a loss of credibility. It is kind of understandable why certain scientists tend to emphasize their own findings at a disproportionate degree – even though that doesn’t excuse their sloppy work. Imagine that you have devoted your entire life to digging in the dirt for fossils, working in a laboratory, or studying computer programs for decades. One discovery that could be of significance might just be what you need in order to keep going after years of fruitless work. If that discovery then seems to arrive, you might not be as distant and objective as you should be. We are only humans – and we might get weak sometimes.
It is safe to say that even amongst scientists some people are driven by ideology. How objective can a result be if one is not even open for arguments other than the desired ones? Partially, the outcomes of scientific studies are a matter of interpretation. If a scientist wants to get a certain result since he is expecting it for years, he might design his studies in a way that they will produce the desired results. As everywhere, some people are just not good at doing what they are doing. A scientist should always stay objective, but I am sure many are not. A degree does not always equal qualification. We would do ourselves a favor if we understood that.
I am afraid it happens quite regularly that at least two independent groups or scientists work on the same topic. They might not even know that that is the case. The problem is that, as with other topics, competition sometimes is more dominant than cooperation. If all scientific institutions around the world would share everything they do and know and everyone worked together as a result, scientific progress might be much more efficient. Yes, national and international cooperation between distinct scientific institutes do exist, but due to the omnipresent race for funds and prestige many scientists just try to publish their results before someone else does who is working on the same topic. This does not only lead to a waste of time, money, and effort since different groups work on the same topic, it might also lead to a premature publication of results in order to win the race. Under such circumstances, it might be questionable if such results would have been achieved and analyzed with the necessary care.
Science is done by human beings. Thus, it is also prone to universal weaknesses of our species that can lead to fraud, lies, and deceit. Bear in mind that such negative attributes have nothing to do with science itself, but only with the human beings that are behind it. Therefore, it doesn’t come as much of a surprise that plagiarism is also a factor. It is pretty safe to say that a certain amount of academics have gotten their degree through cheating. Ghostwriters of theses and publications might be more common than one thinks. Bad people do bad things – and it would be either foolish or downright wrong to claim that there are no bad or unqualified people in science. The problem is that many scientists have worked very hard to get where they are. They are the ones that suffer the most when rotten apples put a whole academic field into question. What is important to remember is that most scientists who hold a degree have gotten there through honest and hard work. However, that does not necessarily mean that everyone who holds a degree is honest or even qualified.
It goes without saying that much more could be said about the weaknesses of science or, more precisely, of the people doing the science. However, science is more than ever a powerful and credible source that usually corrects its own mistakes. Many things we believed in in the past are now obsolete. Every year of research just shows us how much more there still is to be learned. Bad theories will be replaced by better theories which prove to be the most plausible regarding the data currently available. Errors or sloppy work will not remain for long due to the progressive scientific atmosphere of doubt, debate, and competition. Yes, mistakes happen and yes, science has to keep reminding itself of its limitations and intentions – but the best answer to bad science is always better science. There is no desirable alternative.
Evolution – Facts, Myths, and Misunderstandings
Part 18: Evolution, Superstition, and the Supernatural
After 17 parts on various topics of evolution, it is legitimate to ask why human beings are so prone to irrational beliefs. Even though many parts of our behavior are not predetermined by our genes, the potential that lies within us is determined by our heritage. How is it possible that a costly trait such as superstition was preserved throughout evolution? After all, the time and the resources that are spent on supernatural beliefs do not seem to provide any crucial advantage regarding the survival of the individual. Is the theory of evolution so compelling that it offers an explanation for the existence of beliefs that deny its validity?
I think it does. However, I would not consider myself an adaptionist who believes that everything that is has a function since it otherwise wouldn’t have been sustained through the course of evolution. I do believe – as pointed out earlier (part 5 and others) – that luck or coincidence also have their part in the development of living beings. This form of belief, however, must not be confused with the irrational beliefs in the supernatural. My assumptions are based on the scientific knowledge that I have gained so far. If the available evidence changes, my beliefs might change as well in contrast to religious convictions which might never be altered. I do believe that some organs or structures in living beings might be mere side effects of other, more important developments. We might desperately try to find scientific explanations for the function of a chin in humans – or we could be open for the possibility that it might be a structure without greater significance that evolved for no particular reason. I prefer the later approach.
Obedience and Reward
Now, does the theory of evolution provide any answers regarding the question where the potential in humans for supernatural beliefs came from? I think the answer contains two major points: obedience and reward. Almost all religions are based on obedience. You have to do what the supernatural creator wants you to do if you do not want to get punished. In fact, disobedience is penalized with eternal suffering in most belief systems. Humans clearly contain a seed that – if properly nourished – can be grown to loyal obedience. One of the most plausible explanations regarding this characteristic deals with the behavior of offspring. In the past, obeying your parents could have been crucial for survival. If an infant was taught “Do not touch that animal!” it probably had a good reason to obey. Infants that did not listen to their parents might have been hurt or even killed by dangers known to the elders. On the other hand, the obedient child might have had an essential advantage regarding its own survival, increasing the chances of spreading the genes that might have influenced that characteristic.
The other main focus lies on rewards and positive experiences. If our ancestors incidentally celebrated a feast before the rain set in, they might have thought that their rhythmic moves had something to do with the weather. Hence, the next time they needed rain they would have tried to repeat what they did the first time in order to produce the same results. However, dancing for rain would certainly be defined by any scientific inquiry as pure superstition. Nevertheless, such behavior is definitely beneficial in many cases. If a living being realizes the correlation between an action and a desirable result and if it repeats the action, it will benefit from the discovered connections. When our ancestors learned that cooking had positive effects regarding the food they ate, certain diseases might have been diminished as a result. When early Homo species realized that chopping stones provided them with sharp edges that could be used as tools, they discovered the basics of a whole new branch of technology. It is clear that our species wouldn’t be what it is today if it wasn’t for our superb ability to connect the dots. Nevertheless, this property is everything but exclusively human.
If a bird is placed in a cage and if food is thrown into the cage at constant rates, many birds soon develop behavioral patterns based on what they did when the food entered the cage for the first time. They obviously think that their behavior influences the food supply although it clearly does not. These and similar experiments where done by Burrhus Frederic Skinner, who was especially known for his so called Skinner-Box. The point is that many animals have a similar ability when it comes to understanding correlations. The problem is that sometimes animals, including humans, are too limited intellectually to realize if two things are actually connected or if a desirable result came into being by chance independent of the performed action. A bird bowing its head in order to get food is as mislead as a human who thinks that his dance will make it rain.
Even if there are rational explanations for why humans are born with the described potentials, how can supernatural experiences be explained? First of all, what certain people experience as something supernatural is usually something that they just can’t explain rationally at the moment. The Homo sapiens is a pattern seeking animal that will rather accept an irrational explanation than having no answer at all. The problem is that people who are prone to supernatural beliefs will hardly accept the scientific explanation that might clear up the mystery in most cases. All of us have moments of doubt and confusion at some point in time, but it depends on our history if we are going to look for a reasonable explanation or not.
A few years ago, I woke up at night and opened my eyes. I was seriously scared as I thought that I saw someone walking through my room. The worst thing was that I thought this person was me. It happened more than once that I woke up at night and thought that someone else was standing in the corner of my room or sitting on my couch. If I was superstitious, I am sure I could have told myself that I was having visions. However, even though I was scared, I knew that nobody else could be in the room. I waited until my eyes had adapted to the dark – and realized that I was startled by a shirt hanging over a chair or by a picture on the wall. Sometimes I even got up and turned the light on – with the same result. If we are half awake, we are delusional. It would be rash to consider experiences made in that state as real. Moreover, dreams themselves can be very confusing, but no matter what we see or experience – it is always there in our heads before we go to bed. Dead people don’t speak to us – our subconscious does.
Today, people suffering from epilepsy and other brain related diseases can be operated on while remaining conscious. Some of them reported the most bizarre experiences while the physicians touched their uncovered brains. They floated through the operating room looking down on themselves, they saw pictures from their childhood, or they heard voices. In addition, people who suffer from seizures often state that while their brain is causing them trouble, they have the most startling and fascinating experiences. The point is that many supernatural experiences can be explained in materialistic terms. Even electromagnetic waves are known to cause hallucinations. Is it surprising then that people have certain experiences when our homes and our world in general are full of waves, transponders, and receivers? Even though there are scientific explanations, many people refuse or fail to understand that their experiences have nothing to do with the supernatural. They believe because they want to – and the power of will often beats the power of reason. In certain ways, the potential to obey and the potential to realize correlations was essential for the rapid growth of the human knowledge and mind. Today, however, these traits lead to behaviors that seem to be artifacts of our forefathers rather than rational acts in many cases.
Evolution – Facts, Myths, and Misunderstandings
Part 17: Why Design doesn’t Require a Designer
If there is one reoccurring theme in debates with creationists it is this statement: everything that is designed had a designer. A watch had a watchmaker, a painting had a painter, a house had a builder, a bridge had an architect, and so on. If one walked along the beach and stumbled upon letters written in the sand, it would be obvious that those letters didn’t get there by chance but were drawn by a person. Thus, due to the design that is all around us in natural structures there must have been a designer. Despite the fact that creationism was ruled unscientific by the highest courts of the United States of America several times, it has never given up its ambitions to make its way into schools and public life. Its latest camouflage, intelligent design, is yet another attempt to regain influence in secular societies. The foundations are twofold: first, everything that looks as if it was designed was indeed designed by some form of intelligence. Second, many structures are so sophisticated that they couldn’t function if a single part was missing. Thus, all parts had to be created at the same time. This is known as the argument of irreducible complexity which was already considered in part 12. This train of thought, as persuasive as it might be for someone who is not familiar with the topic, is fundamentally flawed in several ways. Sometimes explanations based on intelligent design are so absurd that they ridicule the person making the statement. Two examples are the attempts to explain why the banana is perfectly designed for the hand and mouth of a human being and why a jar of peanut butter is supposed to be the nightmare of an atheist. For the sake of completeness, it shall be explained why such examples are nonsense at the end of this article.
The living vs. the non-living
The argument of design is repeating one mistake over and over again: it compares the living with the non-living. There are no natural laws that guide and influence the assembly of a plane. No natural mechanism is going to select cars which are safer over those which are unsafe. There is no competition between computers, only between the companies producing them. Artificial objects cannot reproduce, adapt, or – in general – evolve. This is a crucial point that has to be understood: natural structures are the way they are because of their history of change and adaptation. All the processes and mechanisms that were presented throughout this series do not apply to manmade, non-living objects. Thus, they cannot be compared with each other. It is easy to visualize why this train of thought is flawed. A container that is leaking has to get fixed. Afterwards, it is obvious that someone repaired this object since the fixed area is a sign of design. Following creationist logic and applying this train of thought to living things, a scab is a sign of design and must have a designer. The only problem is: who actually thinks that a scab is designed rather than the result of the natural blood clotting process?
A computer can only function if its builder connects its parts right. Who connects the neurons of our brains through synapses as we age? Is a designer behind this as well? Or isn’t it just natural processes guiding the development via biochemical cascades? Was the variety of dogs achieved by assembling the individuals of different races in a laboratory? Or was it achieved through evolutionary processes, accelerated by the human influence? If one walks through a forest and suddenly spots a picture that is attached to a tree, it is obvious that some form of intelligence drew the picture and put it there. Thus, if one finds an apple hanging on an apple tree it is obvious that someone put the apple there – or is it?
So what is the great fallacy of the argument of design? Everything that wouldn’t exist without human beings can only come into being through intelligence. That is obvious. However, these things cannot be compared with natural structures that appear independent of human beings. Using such comparisons is absurd as shown by the examples above. There are naturalistic explanations for natural processes and artificial explanations for artificial structures. These two cannot be mixed. If the example of the apple tree is considered again, what reason would one have to believe that the apple was put there by some form of intelligence? None, because apples growing on apple trees is a natural process that can be explained with naturalistic explanations. The same is true for everything else that is non-anthropogenic. The evolution of natural structures and their development during the growth of the living being are both subject to natural processes. If there were no intermediate forms of the eye between human beings and archaic cells, intelligent design might have a point. However, as one moves up the phylogentic tree (or tree of evolution), several variations of organs used for the perception of visual cues can be found with increasing complexity starting with single-celled organisms found in the genus of Euglena. The complexity of the eye of an octopus might even exceed the one of its vertebrate counterpart even though it is a completely different phylum, visualizing that several paths can lead to the development of eyes throughout evolution (convergent evolution, see part 15). A variety of rock formations might look like they could have been designed by some form of intelligence, but we are well aware that they are the results of plate tectonics and erosion. We can witness today that islands are born in the ocean, for example south of El Hierro (Canary Islands). Who is the designer? No one is because we have naturalistic explanations to explain what is going on, namely the eruption of submarine volcanoes. The list could go on endlessly. We have and use naturalistic explanations for natural processes. Why should we even consider superstition and unproven claims as a valid alternative?
You need faith in order to believe that everything came into being by chance
This statement is also commonly made by creationists or proponents of Intelligent Design. Frankly, it holds some truth even though most of it is based again on a gross misunderstanding of science. The shred of truth is that scientists have to believe in certain things as well. The main difference is that this kind of belief is based on evidence rather than faith. The beauty of science is that different explanations and approaches compete with each other, causing a competitive and critical environment that removes mistakes in most cases. For example, not everyone believes in plate tectonics. Some people think that the changes observed regarding mountain ranges and the development of the continents can be explained by an expansion of the earth. Scientists consider the evidence that is available, evaluate the possible explanations, and decide which approach explains a certain observation the best in their opinion. Most scientists still support the theory of plate tectonics, but it is important to know that an educated opposition exists that keeps the need for improvement and further research up in contrast to “alternative” explanations such as intelligent design.
It is a gross misunderstanding of science to state that without a designer, everything would just be the result of accidents. This is not true. In fact, no thorough evolutionary biologist would ever claim that everything happened just by chance. Some people do not seem to understand that certain evolutionary mechanisms are chance events (such as genetic drift and mutation) while others are not random at all (especially natural selection; see also part 2, 5, 6, and 7). As explained in part 12, certain processes are guided by a metaphorical funnel. The outcome is not due to chance but the result of various factors interacting with each other. If everything was an accident, living beings would not possess the intricate adaptations that enable them to survive in their respective environments. Only the gradual process of adaptation and change renders a living being fit under the given circumstances. This has nothing to do with chance or randomness. Maybe the difference can be visualized with the following example.
The birth of a particular person is a chance event (see part 12), but what this human being turns into as it ages is not due to chance at all. Certain circumstances (parents, school, friends, etc.) are going to influence and guide the development in a way that the person will be fit for and adapted to the surrounding society. Even though the birth of that very person was due to chance, the factors that influence the individual are not chance events at all. One could argue that environmental influences are chance events after all since nobody can choose its surroundings. That is true, but the point still is that the given circumstances mold a person in order to survive in a non-random fashion. In a nutshell, chance events give rise to numerous human beings (variety). Who is going to be more successful later in life will be determined by non-random processes. Choosing someone for his intelligence, diligence, connections, creativity, or physical strength is non-random. Natural selection works and acts in comparable ways.
Is intelligent design (ID) an alternative scientific theory?
This question was considered in other parts as well and the answer can be short and simple. ID cannot be proven wrong in theory (falsifiability), it does not produce any evidence or scientific results itself (or are there professors of ID at famous universities or publications regarding ID in well renowned journals?), critical debates and alternative explanations are not a part of its internal affairs, the contents of the arguments do not change or develop, and it states claims that lie outside the reach of science. Thus, ID is everything but science. It fails every single necessary characteristic. It is a superstition that is motivated by religious doctrines. Mankind would do itself a favor if it got rid of it as soon as possible. This will not be the case, however, since superstitious beliefs always have a crucial advantage over science: every human being independent of age or education can understand supernatural claims (God did it – because he says so), but not everyone can understand science. Thus, propagandists will always find an audience.
The flaws of the concept of irreducible complexity were already mentioned in part 12. Here, just another example shall be mentioned. An ID proponent would say that even on the cellular level so many sophisticated processes are connected to each other that the failure of one would cause the collapse of the whole system. An enzyme, for example, is a complex protein structure that guides the pace of biochemical processes. How could such an inevitable part of a system have evolved over time? If it wasn’t there the whole system couldn’t function. Well, the main problem of this train of thought is that one assumes that given structures cannot have been preceded by simpler structures. It should be enough to find a structure much simpler than an enzyme which can nevertheless function as one in order to render the argument of irreducible complexity obsolete. The problem is that such structures are known but the ID arguments won’t change.
Certain single-stranded RNA molecules are known which form elaborate secondary structures and which can take on the role of enzymes. These RNAs are called ribozymes and they might well be an ancient building block that played an important role in the early evolution of life. Another example would be the complex nature of biomembranes with their lipids, proteins, carbohydrates, channels, carriers, etc. Sure, such structures do not just appear over night, but a simple layer surrounding a certain compartment can even be observed on the surface of a fatty soup. Lipids come together and reduce the surface area that is in contact with water. It is a simple principle that can explain how the first primitive surroundings could have formed. Certain organic compounds could have been “trapped” within such layers, serving as the raw material for further developments. Anyhow, the theory of abiogenesis offers more details about the possible development of organic structures and life. The bottom line is: the argument of irreducible complexity is invalid since it ignores the evolutionary past of any organ or structure. Everything had a simpler and less complex predecessor in the past. This is one of the foundations of the theory of evolution.
Another very prominent example that is used by creationists is the complexity of the human eye. With millions of nerve cells, cons and rods, muscles and layers acting in concert how could such a complex structure have evolved step by step? If you take away a single part of the whole construct, it won’t be able to function any more. Well, this example does not make a strong point for at least two reasons. First, there are numerous versions of light sensing organs among animals that range from light sensitive cells to complex eyes with lenses. All of these variations fit well into the picture of increasing complexity in higher taxa. Flatworms do not have eyes as complex as mammals, but they do react to photosensory stimuli. That is what we call seeing. Second, is the human eye really irreducibly complex? What would happen if the cornea had to be removed? Sure, the vision would be blurry – but not absent. The same is true for the lense. What would happen if all the cons would stop functioning? The affected person wouldn’t be blind, but it would lose the ability to see colors. Nevertheless, as long as the rods are functioning, it would be another (lower) quality of seeing, but it would still be seeing. So it seems that even without considering evolutionary relationships the human eye is not irreducibly complex – unless one claims that an inhibited functionality of an organ equals no functionality at all. After all, not all people with impaired vision are considered blind.
If a sharp mind tries to program new computer software, one of the top priorities would be its invulnerability regarding viruses. If the program fails and does not only lead to positive results, it is obvious that the programmer didn’t do a perfect job. However, this would be too much to ask since we are only human beings who make mistakes and who are not perfect. A perfect designer, on the other hand, could program software that was flawless and the possibility of failure wouldn’t exist no matter how intelligent and independent the computer would become. Even if the computer got the order “Do what you want!” it couldn’t do any bad because there is no bad or failure in perfect design. What is the point of this example? The point is that what we see and experience on earth today is everything but perfect. If all is due to the work of a designer, he couldn’t have been a damn good one. Sure, man chose to disobey God after he had given them free will, causing all the bad and evil in the world. It is a test and those who prove themselves worthy will be rewarded with an eternal life in heaven. The simple problem is: what kind of perfect designer created hell and the potential for evil and sin and misery? Didn’t he have the power to create only good things? If he did but he chose not to do it, everything is part of his morbid entertainment. What a nice creator he must be. Moreover, if he is so powerful and can foresee the future, why didn’t he see it coming what man would do with the free will? Again, if he saw it coming, why did he proceed?
Moreover, why aren’t his creations perfect as his followers like to claim? Take the eye as an example. Sure, it sounds great to emphasize the complexity and beauty of its alleged design, but what about the blind spot, an area within the retina that is completely useless for the perception of sensory cues since it doesn’t contain rods and cons? What about cataracts, lazy eyes, retinal detachments, far sightedness, short sightedness, scleritis, glaucoma, and dozens of other eye related diseases? Why can’t we see ultra violet light like bees can? Why does it hurt to look in the sun? Why do we see so poorly in the dark or underneath the water? Why do cephalopods have eyes that are partially superior to ours (i.e., they do not have a blind spot)? All of these questions might sound trivial, but if the eye was designed, why is there so much imperfection? On the other hand, such flaws do not pose any problem to the theory of evolution.
One of the fundamental problems with religious arguments is that people only see what they want to see. “How can you not believe in creation? Look at the flowers, the beauty of nature, love, the design of our hands and eyes, the fine-tuning of the universe, etc.” This is an example of cherry picking: make something sound great by ignoring everything that is bad. Ok, a few nice things were named, but what about earthquakes, diarrhea, carnivores that have to kill in order to live, vomit, parasites, infant mortality and infanticide, broken bones, depression, diabetes, and so on. What about all the bad things in the world? Why did the creator come up with that? Did 200,000 Asians die in 2004 during a devastating tsunami or did 75,000 Pakistani lose their lives due to an earthquake in 2005 because they all lived in sin? Or is there bad on the earth that humans can’t influence despite their free will? There is so much bad and imperfection in the world that the notion of an all-powerful creator is either foolish or malicious. Either way, I want no part of it.
The perfectly designed banana and peanut butter – atheists’ nightmares
The internet has provided us with the opportunity to access information at any time and place. Ideally, this kind of forum can be very beneficial regarding the freedom of speech and the education of people. On the other hand, today everyone is able to spread propaganda around the world without much effort. This is why the creationists are very active throughout the internet. After all, their goal is to indoctrinate as many people as possible. In the process, some of them ridicule themselves. However, what is really sad is that they find followers who understand as little about science as they do. In one video, a creationist uses a banana as an example for perfect design. The ridges of the peel fit into the groves of the hand, the banana itself is round and fits easily into the mouth, its consistency makes it easy to chew, and so on. Thus, it must have been created by God for the sake of man. One might laugh at this, but it is a sad truth that millions of people follow such people who in my opinion are not that clueless but manipulate others on purpose. After all, in the end they want to sell books or DVDs or other holy merchandise products. So why is the banana example so stupid?
First of all, bananas have undergone a long process of cultivation. Wild-type bananas are oval, green, and they have multiple seeds. Over time, humans “perfected” bananas through breeding until the desired properties were produced. So if Gods creation was a wild-type banana, he didn’t think very carefully about human preferences. Second, determining characteristics that make something look brilliantly designed is completely arbitrary. One can always find a convenient fit if one looks for it long enough. On the other hand, as mentioned above, other explanations which could be just as probable but which are less positive are simply neglected. A banana fits conveniently in ones hand – right. But its long shape also fits in body orifices other than the mouth – why wasn’t that mentioned?
The second example is supposed to question the notion that the prerequisites for life, organic matter and energy, are sufficient to bring forth actual life. First of all, there is much more to the development of life and such a statement again is an oversimplification that visualizes a fundamental lack of scientific knowledge. However, the argument goes as follows: a jar of peanut butter proves science wrong. Why? Because organic matter is there (peanut butter) and energy was added (during the production of the peanut butter), but no life form appears when one opens the jar of peanut butter. It would take too long to talk about the theories regarding the origin of life in detail. However, such a foolish statement doesn’t even deserve a scientific reply since a proponent of this idea might not understand it anyway. Just remember this: one cannot just take certain terms or phrases from a scientific context and use them for supposedly smart examples that prove science wrong when one doesn’t even understand certain scientific fundamentals. Science is more than just simple sentences and explanations everyone can understand immediately. That everyone can understand a superstitious explanation might be considered as a compliment for some religious speakers, but simple doesn’t equal right in many cases. The funny thing is that proponents of ID claim that they are critical thinkers who do not want to follow secular propaganda. How is it then that they all end up repeating the same arguments? As mentioned before, the scientific community is full of debate and doubt, fueling its own progress. How much doubt is allowed within ID? How many alternative theories can be found? How does it progress? Which statements have changed not only in degree over time due to new discoveries? As creationism, ID should stay where it belongs: in churches and the heads of people who are hypocritical enough to deny science when it suits them but make use of its results when they need it.
Evolution – Facts, Myths, and Misunderstandings
Part 16: Evolution and the Homo sapiens
Every aspect of evolution that has been considered throughout this series is related to human beings directly. After all, the Homo sapiens is an animal that was exposed to evolutionary processes as much as any other living being. This part of the series is aimed at applying the discussed principles to the development of our own species. Be aware that this depiction is not supposed to be scientifically accurate in every detail, ready to be published. Instead, it is supposed to be an example of how it could have happened. Regarding the evolution of our own species, many open questions still remain today. This is why every attempt at reconstructing our past should include the humbleness not to claim that it is the ultimate answer.
Possible ancestors of Homo sapiens
Paleontologists are aware that it is extremely difficult to determine the relationship between fossil specimens. After all, diversity is abundant in every species. If a fossil shows certain differences in regard to another, it is anything but easy to evaluate if both specimen are members of the same species or if they are members of distinct species. Even if different species were identified, determining the relationship between them would be very complicated. In the worst case imaginable, two specimens would be described as the same species although their similarities are a product of convergent evolution. On the other side, two members that actually belong to the same species might be defined as not closely related just because the two specimens found represent two extremes of naturally occurring variations within a population – in other words, they could represent the left and right extreme of a bell shaped Gaussian distribution. With this in mind, the following part should not be regarded as a chronology of our ancestry but rather as a visualization of the wealth of fossils that have been found and that could be part of our own lineage.
One of the oldest fossils found that might be part of our lineage is Sahelantropis tchadensis. Like all of the other remains older than two million years (MY) that qualify as the ancestors of the genus Homo, it was found in Africa (Chad) and was dated seven million years old. Other discoveries of similar age were named Orrorin tugenesis (6 MY) and Ardipithecus ramidus (5-6 MY). Be aware that they are not only new species, but members of distinct genuses. How and if they are related is hard to determine. Some scientists believe that they are all part of our ancient family while others think that several bipedal apes walked the African savannas next to each other during the evolution of our own species. Subsequently, only the ancestors of Homo sapiens survived. One constraint, or weakness, that one should be aware of is that paleontologists (for the species named above: Michel Brunet, Brigitte Senut, Tim White) spend a considerable part of their life digging for the remains of ancient life. When they are finally successful, their view might be tainted and they might try to emphasize the importance of their own findings over the results of others. After all, if they succeeded in finding the “Missing Link” their names would become immortal. It is therefore possible, or even probable, that some results are over-accentuated. Even in science competition is a driving force that does not always produce the most accurate results, as shall be mentioned again in part 19.
However, the main point is that several fossils are known that are between 5 and 7 MY old and that qualify as the earliest ancestors of human beings after the split of the last common ancestor into our lineage and into the linage that would lead to chimpanzees and bonobos. The genus that was most likely our direct ancestor was also found and named in Africa: Australopithecus. Dated between four and one MY of age, the following species (besides others) have been described: A. anamensis, A. africanus, A. afarensis (including the famous Lucy fossil found in Ethiopia), A. robustus, A. boisei, and A. aethiopicus. Today, there is little doubt that several of these species coexisted at the same time and even space, such as around Lake Turkana in today’s Kenya and Ethiopia. What is even more interesting is that it is likely that some of those species coexisted with the earliest members of the genus Homo.
As with any biological relationship, sharp boundaries usually cannot be found. Thus, the definition of a genus being distinct from another tends to be arbitrary. However, one of the main characteristics used in distinguishing between the genus Homo and Australopithecus is a larger brain case in the former. H. habilis is commonly described as the first representative of the new genus. Dated 2.5-1.8 MY, the volume of its brain reached about 660-800 cm3 (in comparison to about 450 cm3 in chimpanzees). In the past, the development of tools was also regarded as a major characteristic of the new genus, but later research revealed that members of the genus Australopithecus might have also gained the ability to produce and use tools. Later Homo species were H. ergaster, H. rudolfensis, H. erectus, H. heidelbergensis, and others. It is assumed that H. erectus was the first to leave Africa around two MY ago which is why all fossils of potential human ancestors that were found outside Africa are younger. Another milestone in the evolution of human beings was the controlled use of fire which was possibly achieved by H. erectus as early as 1.6 MY ago. This species might have also been the first to apply systematic hunting as a result of a change in diet towards more meat.
It is interesting to note that a rapid increase in brain size was not one of the earliest changes in our lineage, but rather one of the last. Evidence suggests that our ancestors developed bipedalism first (as early as 5 MYA), followed by a gradual decrease of jaw and teeth size, and tool use (about 2.5 MYA). The rapid increase in brain size began only 0.3 MYA. Thus, the traits mentioned above have not been the result of brain size increase, but rather the cause. However, since the dawn of tool use is separated by the dawn of rapid brain size increase by more than 2 MY, the discovery and acquirement of these skills couldn’t have been the sole driving force behind brain expansion. Instead, the ability to speak and an increase of social bonds and cooperation connected to this form of communication might have been more important. After all, the region of the brain that is crucial for social interactions, the prefrontal cortex, is the region that expanded the most through the course of our evolution.
As mentioned before, it is striking that around 1.5–1.7 MY ago, H. ergaster, H. habilis, H. rudolfensis, and A. boisei might have all coexisted around Lake Turkana. Interestingly, even during the Miocene (5-23 MYA) ancient ape species aggregated around this very geographic location. It is likely that this form of cohabituation triggered the process of diversification through niche divergence, sympatric speciation, or competition avoidance. The more differences the hominid species that were in contact with each other developed over time, the less competition they had to face. The lesson to be learned is that evolution brought forth several bipedal apes (radiation). Our species was just lucky enough to survive while all the others went extinct. If it was competition that caused the others to stay behind or inferior adaptations cannot be answered with certainty. Either way, instead of regarding ourselves as something great or planned, we should have the humility to be grateful for our existence despite the odds. For the sake of completeness: modern H. sapiens developed around 0.2 MY ago in eastern Africa and spread soon after. If the new species replaced all other pre-existing species or interbred with them is another point of a yet unresolved debate.
This, of course, is only a short and incomplete overview of what is known about our past. However, the main point of this article is not a chronology of something that can be found in any scientific book, but putting the development of our own species into an evolutionary context. This will be done in the following parts.
Similarities between humans and chimpanzees
We are now sure that chimpanzees and bonobos are our closest biological relatives alive. Thus, knowledge gained about them can greatly enhance the understanding of our own past. One of the major exclusive achievements of the genus Homo is the development and use of tools and weapons – so we thought in the past. The Swiss scientist Christopher Boesch was one of the first who discovered a form of sophisticated tool use among chimpanzees in the Tai National Park in the Ivory Coast. Chimpanzees use nuts as a source of nutrition. Some nuts, however, are protected by a shell that is too hard to be opened without tools. The chimpanzees have learned to master the task by cracking the nuts with a hammer (usually a stone) and an anvil (another stone or a piece of wood). This behavior is remarkable in several ways: first, stones are not commonly found in many parts of tropical rainforests. The apes sometimes keep the stones and bring them when visiting the area where they can find the nuts. Thus, they must have the ability to remember the past and to think about the future. Second, cracking the nuts open is a sophisticated task. It takes juveniles several years of watching and trial and error until they are able to apply their forces appropriately. This is a remarkable example of learning complicated tasks without the ability to speak about it. Third, tool use varies between different chimpanzee populations. In areas where no stones are available, the hammer, as well as the anvil, is a piece of wood leading to the same result.
The ability to pass on knowledge that is not encoded in our genes is usually called culture. Thus, apes have culture as well. Many more examples of tool use (such as “fishing” for termites) are known and they always vary between populations. Forth, and most importantly: this behavior might shed some light on the development of tools and weapons in our species. Boesch searched the soil around the nut cracking hotspots and did not only find massive amounts of empty shells, but also kilograms of chipped stones. Sometimes, just by chance, a stone that is used as a hammer will break, revealing sharp edges. It has not yet been observed in chimpanzees that such sharp edges are utilized as cutting devices, but it is not hard to imagine that this is how the discovery of chipped stones as tools or weapons might have happened in the past between two and three MY ago. What is known from chimpanzees is that they use items as weapons. For example, if they are attacked by cats or other apes, they throw stones or other available objects at the intruder in order to defend themselves. It is possible that a smart chimpanzee might understand the usefulness of a shipped stone some day, triggering a new level of development as it might have happened in our own lineage.
Another similarity between chimpanzees and humans is that chimpanzees also hunt cooperatively from time to time. Chimpanzees have less meat in their diet than we do, but sometimes they do hunt and show astonishing organizational skills in doing so. As with tools, sophisticated hunting techniques in humans are different in degree but not in principle in regard to our closest relatives. Moreover, just as chimpanzees have to be aware of predators (birds of prey, cats, snakes, etc.), so did our ancestors. Bite marks on the bones of fossils indicate that despite the fact that we perfected our hunting skills, human predecessors were still prey (and scavengers) for the longest time. One of the main differences between our species and our closest relatives is the human ability to write (or draw). After the invention of writing, the cultural development and the increase of knowledge exploded. In the past, the entire wisdom of a population would be lost if the group went extinct. The same is true for the distinguished cultures of chimpanzees today. The ability to document knowledge is actually one of the most significant differences between human beings and the other apes (or all animals for that matter).
Regarding social interactions, chimpanzees are again more similar to us than most people think. They also cheat, lie, deceive, form alliances, gang up against other members, reconciliate, hold grudges, love, feel compassion, envy, sadness, and much more. They protect members of their own group and attack intruders from other factions. In their darkest hour, they can even wipe out a whole other group, analogous to genocide. There isn’t enough room in this article to talk about all the sophisticated forms of social behavior in apes and their similarities to ours. However, in order to learn more about the topic I would suggest reading the works of the wonderfully devoted Jane Goodall or other experts of primatology such as Frans de Waal.
There are several other traits that we share with the other apes. Apes are unique in that they have opposable thumbs that enable them to pick up delicate or small objects. They have grasping hands, a generalized body plan, they are very flexible, and they can adapt to a variety of different habitats. Take chimpanzees. Some populations inhabit dense low land rainforests, while others roam through open grasslands. Moreover, even certain universal patterns of behavioral taboos, such as an avoidance of sexual intercourse with siblings, apply to most humans and the other apes alike. In fact, adolescent members of chimpanzees (females), bonobos (males), and gorillas (females) have to leave the group they we born in and try to find another in order to avoid inbreeding.
Environmental conditions that might have influenced human evolution
If one understands that the differences between human beings and their closest relatives are variations rather than novelties, it might be easier to understand how both are derived from a common ancestor. As explained in part 4, speciation is triggered in some cases by changing environmental conditions. Climatic change has probably always played a major role regarding evolutionary adaptations.
Apes originated about 30 MY ago when the tropical rainforests had reached their widest expansions. Following, the climate became constantly cooler and drier. The rain forests shrunk and revealed fragmented patches with then isolated populations – ideal prerequisites for speciation. The first major abrupt cooling event occurred about 5 MY ago, coinciding with the origin of our lineage (hominis or hominids, depending on the source). The second major cooling event caused the build-up of Arctic ice and the expansion of Antarctic ice between 2.5 and 3.5 MY ago. Afterwards, two different trends regarding the evolution of bipedal apes occurred: the increase of jaw and tooth size as well as robustness on the one hand (for example A. boisei) and the increase of brain capacity on the other (genus Homo). It is plausible that these two adaptations were the result of the same selective pressure: a change in available food sources. While A. boisei might have gained the ability to chew and digest plants that were found in the expanding savannas (grass, nuts, roots), members of the genus Homo might have gained the ability to process food and to hunt, requiring higher cognitive skills.
The fluctuations of the climate increased considerably within the last 2 MY, increasing the selective pressure. The oscillation of ice ages brought about glaciations in central Europe at some periods and climates warm enough for hippopotamuses in Germany at others. The tropical rainforests in Africa shrunk to a mere 10% of their widest expansion, with isolated patches in east Africa, the predicted region of the origin of H. sapiens. It might have been these extreme climatic oscillations and the according selection pressures that triggered the migration of our ancestors out of Africa. Later, the superior adaptive skills of H. sapiens might have enabled our ancestors to survive the harsh and fast changing environmental conditions within the last 0.1 MY while our close relatives, such as H. neanderthalensis, went extinct.
Besides climate, tectonic movements and geographical changes might be another important aspect regarding abiotic factors that influence evolutionary change. Tectonic plates move about 5-10 cm per year. We know now that the shape of the continents we see today was much different in the past. Plate tectonics is still responsible for major life threatening events such as volcano eruptions, earthquakes, and mountain formations (which are not life threatening of course). About 15 MY ago, a north to south uplift of a plate margin began in eastern Africa, leading to what is now known as the domes and rift valley in Kenya and Ethiopia. This new mountain range presented a barrier for cloud movements, causing a rain shadow for the eastern part of the continent. Thus, the vegetation changed, continuous forests were replaced and the remaining habitats were fragmented, leading to an increase of ecological diversity and new niches. It is thinkable that this was the environment in which our ancestors evolved – separated by a mountain range from the lineage that would bring forth chimpanzees and bonobos.
The enormous effects of the interplay of geographical changes and climate on evolutionary change are known from several examples. To name only one of them: fossilized elephant remains have been found on the Italian island of Sicily. These fossils were remarkable since they revealed that this population of elephants consisted of individuals that were only as tall as goats. What happened? It is known that the Mediterranean Sea ran dry several times in the past, leaving behind a salty dessert. Without the aquatic barrier, animals could move north towards Europe. Some elephants reached Sicily (and other islands) and stayed for good. When certain circumstances changed, however, the Mediterranean Sea filled up with water again, trapping the elephant population on the island. It is a general principle in evolutionary biology that a restriction of space and food (possibly in correlation with a lack of big predators) leads to a decrease in size over time. Here, the interplay of geographical and climatic factors caused a massive change in a species, leading to specimens more than ten times smaller than their relatives. Even for the genus Homo such an example might exist.
In 2003 on the Indonesian Island of Flores, scientists unearthed the remains of a species they termed Homo floresiensis3/p.427. The fossil stood only about one meter tall and had a brain capacity comparable to those of chimpanzees. Since its discovery, speculations have gone wild. H. floresiensis might have been an example of a Homo lineage that experienced insular dwarfism and that went extinct only a few thousand years ago. Other interpretations suggest that the remains represent the youngest fossils of H. erectus known today. Without further findings, however, it seems unlikely that the real identity of this specimen will be resolved soon.
Biotic factors that might have influenced human evolution
Here, pretty much all aspects mentioned in parts 1 through 8 could be applied. As in any other species, populations of our ancestors consisted of unique individuals that provided the diversity necessary for evolutionary change. Competition was everywhere: within the group, between groups, and also regarding predators. Bite marks on bones clearly show that apes, even if they had gained the ability to walk on two legs, fell victim to big cats such as lions or hyenas. Thus, those sensory systems and those physical adaptations that helped to spot the predator and enabled the prey to escape more successfully were favored and maintained throughout evolution. The sharp vision typical for humans today might have been an adaptation to big game hunting, but it might also have served an important role in the past when it came to the detection of threats.
Competition between rivaling groups was certainly also of significance regarding evolutionary change. It was essential for survival to protect group members and territories including all its resources. The development of tools and weapons might not only have been fueled by hunting, but also by warfare. Some anthropologists even think the evolution of man was inextricably linked to wars. The hostility towards competitors in turn led to sophisticated relationships within a group. Our ancestors proved to be successful because they became one of the most social species on earth. An individual could not have survived for long on its own. It relied on the help and support provided by the group. It is likely that the increased sociality of our ancestors was one of the main causes for an increase in brain size. In comparison to other apes, the biggest difference is an enormously enlarged prefrontal cortex in humans. It is this part of the brain that is responsible for our social and cognitive abilities.
A vivid example of our reliance on other human beings is birth. In apes, the baby is born with its face up, enabling the mother to assist herself in the procedure. Because of changes in human anatomy due to the adaptations for walking on two legs, the birth canal in humans has changed in a way that a woman now relies on assistance when she is in labor. It is obvious that such social abilities are connected to brain structure. Medical records show cases of people who lost the ability of interacting properly with other human beings after their prefrontal cortex was damaged. Nevertheless, in comparison to our closest relatives, human sociality differs only in degree from those of chimpanzees. Chimpanzees are known to form bonds that sometimes last for a lifetime. Also, scientists today believe that the purpose of grooming is social bonding rather than just the removal of parasites. Apes sometimes cuddle, kiss, and hold hands just as humans do.
However, the ability to speak and to use language is more unique to humans. Since speech is such an effective means of communication, it is thinkable that those individuals that possessed the necessary neuronal equipment to develop this trait had a considerable advantage and therefore could increase their reproductive success. This did not happen from one generation to another, of course. As with any trait, differences were probably subtle and added up over thousands of years. Nevertheless, minor changes can already be sufficient in order to increase the chances of survival and reproduction. Remember the vision example from part 2: natural selection wouldn’t allow poor vision or blindness to evolve in ancient African Bushmen. If a hunter sees a lion only two meters later than the other men in the group, this minor difference in acuity of vision might already be a lethal disadvantage.
Thus, changes can indeed increase the reproductive success of an individual no matter how small they are. The same is true for hunting: those males who were faster, more enduring, or more skilled in the production and use of weapons might have been more successful hunters and therefore could have increased the chances of survival for themselves and their kin. It is also likely that certain traits necessary for hunting, such as prediction, cooperation, and spatial orientation, favored higher cognitive skills and fueled the increase of brain size. As mentioned above, brain size did not increase considerably until the dawn of the genus Homo about two MY ago.
Some evidence suggests that human ancestors lived as scavengers before they perfected their hunting skills. Such evidence, besides others, is first: that bones of prey species show cut marks of stone tools on top of bite marks of big cats and second: the coincidence that human and hyena tape worms diverged about 1.8 MY ago, indicating that both predators shared similar food beforehand. Besides changes in brain size, a trend towards a smaller masticatory system is another indicator for a change in diet. Fruit and meat are easier to digest than leaves or grass. Gorillas, for example, rely mostly on a leafy diet. Their bellies look big because their intestines have to be long in order to digest the plants efficiently. Gut size decreased in human ancestors as the diet changed since costly traits are usually selected against naturally if not needed.
Sexual selection is another aspect that certainly played a role in human evolution. The one unmistakable characteristic that proves that it did is sexual dimorphism. Men are usually taller and stronger than women. In many non-human apes, males possess larger canine teeth than females. It is likely that certain traits or behaviors have evolved because the females chose them. Some scientists even suggest that the evolution of bipedality was influenced by sexual selection. A male that was able to walk on two legs had its hands free to carry food. Thus, females might have chosen better providers. For the same reason, stronger, taller, or smarter males might have had a greater reproductive success. There is no convincing argument for the advantages of hair loss in the human species in contrast to other species that lived under similar circumstances. After all, a lack of hair increases the vulnerability to the radiation of the sun on the one hand and a weakened adaptation to cold on the other. Maybe females preferred males that were less hairy for whatever reason. Even though the influence of sexual selection is often speculative, it should not be neglected regarding evolutionary change.
Another important abiotic factor that influenced the course of the development of our species was coevolution. As described in part 7, no population lives in isolation from all other living beings. Thus, changes in one group influence neighboring groups. Certain current traits of the human species might therefore be the result of an arms race with parasites, predators, prey, competitors, edible or poisonous plants, and others. One thing seems to be obvious however: for some reason human ancestors gained the ability to adapt faster to a variety of different environmental conditions after they left Africa, enabling them to outcompete and displace a variety of other species. Subsequently, H. sapiens even succeeded in partially decoupling its own development from natural evolution, a distinction that is known as cultural evolution vs. biological evolution. This process started about 12,000 years ago when our ancestors settled down and discovered farming and the domestication of animals. From then on, the human species became less and less dependent on its environment which we learned to shape for our needs more and more.
The evolution of bipedality
One of the main differences between humans and non-human apes is our ability to walk on two legs for a long amount of time. As many other human traits, bipedality is not entirely a biological novelty since chimpanzees and bonobos can walk or stand on two legs for a short amount of time as well. However, bipedality was perfected throughout the evolution of our lineage. The question therefore is: why did we leave the trees and decide to walk exclusively on two legs? What are the advantages?
There are at least a dozen hypotheses about the development of bipedality. It is probably more reasonable to assume that several reasons played a role instead of searching for the one ultimate theory. Also, once the ability was acquired, it could have been beneficial for other tasks as well. Starting in the trees, some scientists think that standing on two legs might have been beneficial in order to reach fruit from other branches. In this scenario, the origin of bipedality would have nothing to do with the ability to walk on two legs on the ground. In this sense, it would have been a pre-adaptation like the air bladder of fish that turned into the lungs of later species. Some primates have been observed wading through water. Standing on two legs can keep them dry. It is possible that human life forms developed in the vicinity of lakes or rivers. Maybe they waded through the water frequently in order to collect food high in calories such as crustaceans or clams.
When the climate cooled and forests became patchier, being able to walk from one group of trees to another on two legs might have been beneficial too in order to increase the field of vision. In addition, when standing upright, less of the body surface is exposed to the radiation of the sun and the head is further away from the heat radiation coming from the ground. Sexual selection could have played a role as mentioned above. Besides the possibility that females might have chosen bipedal males for their attractiveness, it is also possible that those males that could stand up longer in displays intimidated other males more when competing over mating partners. Being taller could have also been beneficial for the detection of predators in the savanna. Later, free hands were essential for the efficient use of tools and weapons.
Bipedality has one advantage that can actually be determined empirically: it is the most energy efficient locomotion when distances are great and the movement is rather slow. These circumstances might have been essential for the development of big game hunting. It was important to track migrating herds or animals that were injured in an attack. Due to the lower energy demands, prey animals had to stop and rest earlier than human ancestors had to, leaving the later with a lethal advantage. Some scientists have calculated that it paid to walk on two legs as soon as our ancestors spent more than 60% of their time on the ground. This development might have been aided by the circumstance that out of all tropical rainforests, those in Africa tend to be the driest, lowest, and least dense, providing plenty of opportunities for a switch to a more terrestrial locomotion.
Whatever the reason for its development, exclusive bipedality in mammals was a novel characteristic that enabled new adaptive radiations. It is more than probable that many more extinct species that possessed this trait will be discovered as research continues. Certain trends already seem to be universal regarding known fossils and our own species. In comparison to primates living in trees, bipedal apes have longer legs, straight limb bones, toes, and fingers, an S-shaped spine, a shorter but broader pelvis, lined up toes and a plantar arch in a stiff foot, enlarged joint surface areas, feet that are closer together (different valgus angles), and many other characteristics. The evolutionary advantages of all of these adaptations seem to be obvious due to the necessary anatomical rearrangements that came with an upright posture. What is important to understand is that, as with all other evolutionary changes, adaptations regarding bipedal locomotion are the result of millions of years of subtle alterations. The same mechanisms that caused the split of a common ancestor in lions and tigers also caused the spilt of a common ancestor in chimpanzees and human beings.
General ecological trends
Since human beings are only one out of millions of species, they were part of naturally occurring trends for the longest part of their history. Bipedality was a novel trait in apes that enabled adaptive radiations bringing forth several new species. In general, the diversity of life and the amount of species has increased constantly since the beginning of life. On the one hand, the fragmentation of the continents after the split up of Gondwana increased the diversity of living conditions and introduced new ecological niches. Living beings in turn developed adaptations in order to cope with the new environments again and again, bringing forth ever new variations on the theme of life. Even mass extinctions, which have devastated the diversity of life time and again, could not reverse the general trend. Life has always found a way and flourished anew after the most destructive strikes. Even the sixth mass extinction that is taking place as we speak will not threaten life on earth. In general, the dominant life forms were those who didn’t survive the mass extinctions. Evolution, however, won’t care and it will fill the abandoned niches again with new life forms that will replace older ones. What we have to understand is that the H. sapiens does not threaten life in general, but that it endangers its own existence. If mankind fails and vanishes from the face of the earth, in a few million years the damage that it has caused will fade away and we will be only one out of countless species that have gone extinct. Human existence might go down in history as nothing more than a wink of evolution.
However, regarding our past it is important to take into account that apes usually do not live in huge herds, but rather in small groups. The smaller the population is, the higher the chances of extinction as well as speciation are. Sexual selection, mutations, genetic drift, and other random events have a greater impact when the numbers are smaller since new variations will have a better chance of becoming established.
Chimpanzees, bonobos, and gorillas live in small groups throughout Africa. It is known today that the genetic differences between isolated populations of either species are tremendous to the extent that they might even represent distinct species. There is not only one species of gorillas as has been previously thought. Western lowland gorillas and mountain gorillas differ significantly, to name only one example. Over time, such populations have ceased to exchange genes with each other and would certainly diverge even more in the future if they had the chance and weren’t driven towards extinction by humans. It is likely that similar events caused the radiation of bipedal apes. Our ancestors certainly lived in small groups as well. In order to avoid inbreeding, some individuals (such as females in chimpanzees and males in bonobos) might have been exchanged between the groups on a local level. However, such populations might have strived to isolate themselves from other more distant groups in order to avoid competition.
If a migrating group found a suitable habitat, it might have flourished and spread. Due to such a founder effect, all descendants would have shared the peculiarities of their forefathers. Moreover, if two closely related species coexisted in the same area, they might have developed and evolved in different directions in order to decrease the competitive pressure (ecological character displacement). As mentioned above, it is likely that several hominid species coexisted at Lake Turkana about 1.5 MYA. They had to be different in some ways, be it the food that they ate, their activity patterns, life history traits, or other aspects.
For any animal, group life comes with certain disadvantages: competition might arise over mating partners or food, diseases might spread more rapidly, and it is easier for a predator to spot a group instead of a single animal. However, the fact that many of those animals that are considered the most intelligent (many apes, dogs, dolphins) live in groups shows that this form of social organization must come with considerable advantages. The more individuals a group contains, the better the chances are of defending themselves from a predator. Also, groups are able to defend certain territories against competitors where the individual is not. It might be easier to find new sources of food since many eyes see more than just two. Last and foremost, group life provides a base for bonding. Weaknesses of an individual will be taken care of in the shelter of the group. The result was the development of a complex social behavior that was certainly crucial for the evolution of the H. sapiens. In a group, individuals must be identified and remembered. Who helped me in the past and who, in turn, deserves my assistance? It pays to be able to predict what others are going to do and it might even be beneficial to manipulate others in a way so that they will do what you want. Who is my friend, who is my opponent? Who can I rely on and who should I share my food with? Finally, the bonds within a group became so tight that individuals were even able to feel for others beyond their own selfish instincts – a trait that we call empathy and that can be observed to some extent in some other animals (such as apes) as well.
Considering our more distant ancestors, certain traits that are typical for humans are just continuations of trends seen in other primates as well. Those primates, for example, that rely on insects and fruit instead of leaves tend to have bigger brains. The reason might be that it is easy to find leaves, but it is a more difficult task to find ripe fruit or other living beings to feed on, requiring higher cognitive skills. In comparison to other mammalian groups, the gestation period in primates is longer, litter size is smaller, parental care is increased, and social learning continues for a longer time.
The same trends can be found in H. sapiens – taken to the extremes. When human babies are born, they are the most helpless and depending creatures imaginable. Primate babies are usually able to hold on to their mothers and open their eyes pretty soon after birth. By the way, this is why human babies are still born with the instinct to grab everything that they can get between their fingers. Primate babies are usually considered as being precocial (well developed at birth). Human babies, however, are so helpless that they are often termed secondary altricial (poorly developed at birth). That means that our ancestors were precocial, but somewhere on the path of human evolution we have become altricial – a trait most common in carnivores.
The main difference between humans and other primate species is the massive increase in brain size in the first. In our species, the brain makes up for 2% of our body weight und up to 20% of our energy demand. In chimpanzees, on the other hand, the brain makes up for only 0.9 % of the body weight. This is the reason why H. sapiens has become altricial: the brains of its babies have become so big that they have to be born prematurely. Otherwise the head would become too big for the birth canal. Thus, all human beings are born neurologically premature. Their brains grow at a pace comparable to fetal development for about twelve months after birth which is why some scientists claim that the gestation period of humans actually lasts for at least 21 months. The fontanel on a baby’s head (also known as the soft spot) visualizes that the size of the head is actually the limiting factor when giving birth. Since the bony plates in a baby’s head are not connected yet, they can flex and the brain can be squeezed, reducing its size temporarily in order to fit through the birth canal. In addition, thanks to this flexibility, the head can expand faster due to rapid brain growth after birth than would be possible without fontanelles.
Why scientists believe today that all humans are Africans
Even Darwin in “The Decent of Man” assumed that human beings were related to apes which evolved in Africa. Today, a wealth of evidence supports the “Out-of-Africa-Hypothesis”. First and foremost, the first fossils of modern Homo sapiens were found in Africa. In addition, not a single representative of the genus Australopithecus has been found outside this continent to date. The fossil record suggests that the hominini have been an exclusively African primate tribe until at least 2 MYA. However, as with most aspects of evolution, the most convincing evidence lies in our genes. The geneticist Luigi Luca Cavalli-Sforza, who paved the way for a worldwide comparison of human diversity with his ground breaking work, revealed that the genetic differences between human beings outside of Africa are smaller than those between Africans. What is the reason for this circumstance? There seems to be only one plausible explanation.
Imagine a huge forest separated from other forests by a vast dessert. Animals, such as deer, are free to move within the forest, but it is impossible for them to migrate to other localities. Over thousands of years of evolution, certain subgroups of deer (given enough space) will adapt to certain parts of the forest, for example to a part with less trees and more grass. Contact to other deer groups might not be impossible, but it won’t be the rule. So over time the genetic diversity within the forest will increase regarding deer (and all the other living beings). If somehow after thousands of years of isolation a group of deer finally succeeds in migrating out of the forest, it will become the founder population of all deer outside the forest (see part 4). If the ancestors of this founder population spread and colonize the whole world, it is obvious that the genetic differences between them will be rather small independent of the distance they have traveled. However, the differences between the founder population and the deer population in the dryer part of the forest will be much bigger since more time has passed since their separation.
The same is assumed to be true for humans. Since the genetic differences between, for example, a Japanese and a Brazilian are smaller than those between an African from Morocco and one from Zimbabwe, it is plausible to assume that human ancestors lived in Africa for a rather long period of time before the first group of Homo sapiens left the continent. It would be hard to explain – if not impossible – Cavalli-Sforzas observations if this were not the case. As a side note, his research also made a strong case against racism since it revealed how close all human beings are actually related. In other words, there is no scientific justification whatsoever for the concept of races in Homo sapiens. Genetically, we are more or less identical. As a comparison to humans, ten times more differences are found amongst the mitochondrial DNA (mtDNA) of chimpanzees from different parts of Africa.
More support for this theory comes from studies of mtDNA. Even though mitochondria are an integral part of any eukaryotic cell, parts of their genetic information are not included in the genome. As a result, mtDNA is only passed on to the next generation as the content of a mitochondrion. Since the cytoplasm of a female egg contains mitochondria while the mitochondria which are part of male sperm do not enter the egg, mtDNA is only passed on by the mother. Further advantages of mtDNA are: more mutations occur over time in variable regions, more copies per cell exist than is the case for genomic DNA, and no recombination events (such as between homologous chromosomes in genomic DNA) occur. All of these properties enable scientists to calculate the time that has passed since two living beings shared their last common ancestor by comparing the differences in their mtDNA which have accumulated over time (molecular clock).
In the case of human beings, such studies have revealed that all members of our species are probably the descendants of a “mitochondrial Eve” which lived about 100,000 YA. That doesn’t mean that she was the only female living at that time, but it means that only her descendants survived. Just look at a family tree of a family that has many children in every generation. Even if there are hundreds of, let’s say, Millers today it is certain that they can all be traced back to this one women who was the first Miller. Some families only have daughters, some have only boys. While for the first the family name might go extinct soon, the name will spread rapidly for the second. The principle is the same: for some reason the descendants of the “mitochondrial Eve” survived while the (female) descendants of other mothers vanished. That doesn’t mean that the “mitochondrial Eve” was genetically superior. It could just mean that her descendants were lucky enough to survive.
Several other genetic approaches based on the concept of the molecular clock are, among others, microsatellites and Alu-sequences. The results also suggested a common ancestor of all human beings between 0.1 and 0.2 MYA. In addition, studies on the variable parts of the Y-chromosome (which is only passed on by men) produced the same result as studies with mtDNA: the genetic differences among human beings are smaller within Africa than outside of it. Today, we have good reasons to believe that the “Out-of-Africa-Hypothesis” is the one that explains the currently available data the best. However, if new developments arise, we must be willing to rethink former predictions. After all, it is that sense of progress and self-correction that separates science from the tenacious adherence of religion to its aged doctrines.
The Homo sapiens – Just another primate and yet unique
Countless properties visualize the relationship of human beings and the other apes. However, like any species, the Homo sapiens has developed unique traits that set it apart from other animals. One striking difference in comparison to our closest relatives is that the peak of ovulation is not visualized in human females by sexual swellings (of the labia). It is possible that the introduction of “silent ovulations” was significant for human beings as a form of child care. If the male doesn’t know when the female is susceptive, it has to spend more time and resources on the mating process to the advantage of the female. Also, if the different males of a group can’t be sure if the female they mated with was at her peak of ovulation, the risk of infanticide decreases since a father wouldn’t attack a child that might be his. After all, an invisible ovulation might be linked to the ever-increasing social complexity throughout the history of Homo sapiens. Males and females started to spend more and more time together and depended on each other’s work. Increasing sociality might have also been the prerequisite for profound changes in the process of birth. Women cannot deliver a baby alone but depend on assistance. Apes, however, are capable of assisting themselves.
Complex speech is a trait that is usually regarded as being unique to humans. However, one must not forget that many animals communicate verbally. Chimpanzees have different warning calls for snakes, cats, birds of prey, and other apes. Also, they produce various noises for social purposes, such as submission or affection. It is true that apes seem to be incapable of understanding grammar. Nevertheless, keep in mind that grammar is something completely arbitrary and irrational. It might be true that humans are superior when it comes to abstract thinking, but that statement does not necessarily have to be true for speech. Several apes in scientific institutions have developed a vast understanding of hundreds of words – even though most of them have no significance for their usual life. The question must be asked how appropriate such comparisons are. As stated above, it is wrong to say that apes do not communicate verbally. They clearly do. They don’t use words comparable to ours and they don’t use grammar – but why should they? If it is not part of their daily life, how can it be considered as a weakness? The problem is that the standards for the evaluation of intelligence are defined by man. If they were defined by elephants, for example, wouldn’t it make sense to say that an animal is smart when it can remember other animals for their whole life (as elephants do)? The point is: many animals communicate verbally. Thus, speech should not be considered as the one unique human trait, since it too is a form of verbal communication which is different in degree, but not in principle. A much more obvious exclusive human skill is writing as mentioned above.
Nevertheless, it is worth mentioning that the human ability to learn what we call speech might be due to rather few genetic differences in comparison to other apes. The FOXP2 gene, for example, has been identified as being crucial for proper speech. It is not functional in apes. Humans suffering from a defect of this gene have to deal with serious speech impediments, including a decreased understanding of grammar. Another example is the gene encoding the sarcomeric myosin heavy chain (MYH). In humans, a frame shift mutation about 2.4 MYA caused a loss of MYH function, meaning a decrease in muscle power (for example in the jaw). The loss of muscle power might have triggered certain developments regarding the brain in order to compensate for the disadvantage. Both examples point out that rather small changes in only a single gene could have lead to major differences in speech or other social skills. The ability to speak even comes with a major disadvantage for human beings: in contrast to other animals, we can choke (see part 14).
Another trait that is commonly considered as being unique to humans is the use of tools and weapons. Today, it is clear that apes and many other animals make use of a great variety of both. What is unique to humans, however, is our ability to handle fire. The controlled use of fire might have been one of the most important achievements of the Homo sapiens (or its ancestors) since it paved the way for following developments: partial independence from environmental factors, the ability to process food, and the ability to fight and enslave all other living beings that might have been superior beforehand. In the end, one thing that is unique about the Homo sapiens undoubtedly is that we are the only species that has the power to influence the entire planet with its actions. It doesn’t happen by accident since we are aware of it. We know that we are causing global harm and yet we proceed – and that is truly unique. Ultimately, it could be us who might cause the most spectacular extinction (our own) of any of the estimated 6,000 primate species which have roamed the face of the earth so far.
When human babies are born, the color of their first diaper content is known beforehand: black. Within the womb, babies are usually covered with a thin layer of hair that is shed before birth. Since babies swallow some of the hair along with the amniotic fluid it ends up in their stomachs and subsequently gives their first diaper content the black color. What is the use of the hair since the temperature within the womb is constant?
Every baby is born with the reflex to grab long before it opens its eyes. However, the chest of women is usually not hairy so what could babies have grabbed onto before humans wore clothes?
Most human beings grow four wisdom teeth which are usually removed as they might cause problems. Why did such an undesirable trait evolve to begin with?
The chromosomes of human beings and apes show great similarities. However, the genetic information of apes is stored in 24 chromosome pairs within the cell while humans have only 23 pairs. Two of the pairs in apes clearly look like they fused over time to chromosome number two in humans – just a coincidence?
The list could be prolonged with countless other examples. “Nothing in Biology makes sense except in the light of evolution” is a famous quote of Theodosius Dobzhansky. When confronted with the overwhelming evidence of evolution, how can someone who took the time to learn and understand the concept deny this simple and yet so powerful theory? The hair on human babies is a rudiment of our hairy ape ancestors. The reflex to grab is so essential to any primate in order to hang on to the mother that even after millions of years of separate evolution it is still part of our nature. When our ancestors started to walk on two legs, the position of the head in accordance to the spine changed. The lower jaw moved back – closer to the neck – leading to a restriction of space for the teeth in the back. Today, due to our posture we simply do not have enough room in our mouth for wisdom teeth. There is no plausible reason to assume that the human chromosome number two does not represent a fused version of two fused chimpanzee chromosomes. Genetic comparisons clearly show the similarities. So the question is: how could all of these examples be explained in a more plausible way based on scientific principles except in the light of evolution? How could a celestial explanation that totally ignores the wealth of imperfections, limitations, and relationships between living beings be more satisfying?
I, for my part, prefer the notion of being the temporary end product of a process that lasted for billions of years. The thought of being the descendant of a handful of 6,000 year old clay, in contrast, belittles and insults my existence. Nature is full of so many fascinating questions that might be solved by well evolved human minds in the future. If God predetermines our life, nothing we do is of any value, nothing we do is free, nothing we do is independent. If people are convinced that God has a plan for them and that everything happens for a reason, they aren’t much more than puppets in a celestial play. Wake up and cherish life as the one brief episode of existence that nature has in stock for you! Do not follow wishful thinking just because you fear death. Do you mind that you weren’t alive in 1367 A.D.? No? Why, then, do you think that you would mind not to be alive in 2132?
As for the evolution of human beings, those individuals who risked doing something new, those who dared to explore, and those who chose technological achievements over superstition were the ones that enabled the progress and development of our species. There is no doubt that we are tied to all other living beings through the bonds of common descent. It is absurd, to say the least, that the powerful process of evolution brought forth a species that can think about and understand its own history and existence but that denies this very process at the same time. Human beings are capable of doing great things intellectually. It is surprising that so many choose to be the dependent slave of a celestial maker instead of the sophisticated outcome of processes that lasted for eons.
Evolution – Facts, Myths, and Misunderstandings
Part 15: Micro vs. Macro – Different Levels of Evolution, same Principles
The evidence for change of living beings is overwhelming – just remember the example of the domestication of dogs mentioned in part 3. Even though the evolutionary change in this case was guided by human influence, the potential for change was inherent and couldn’t be altered. After all, mankind gained the ability to change genes only recently. No serious scientist would question that change occurs over time and since the evidence is so overwhelming even creationists had to admit that species can evolve and adapt. This case could have been closed a long time ago if it wasn’t for the tenacity of religious fundamentalists who came up with another bogus claim instead of accepting that science is right. They launched a campaign claiming that microevolution – the change within a species – is an accepted reality while macroevolution – the change above the species level – is mere fiction. Anyone who understands the theory of evolution should already know that such an arbitrary, manmade categorization is invalid and not applicable. As mentioned in other parts throughout this series, there are no sharp gaps or boundaries in nature. Everything is intertwined. The differences between one kind and another are subtle and fluent. This is why it is so hard for example to find precise definitions for the species concept (see part 4). Stating that certain processes act on a low level but not on a higher level is completely unfounded. How could one walk to their neighbor’s house and then claim that it is impossible to walk to the next village?
Where the micro vs. macro distinction fails
Is there any way to visualize that the distinction between micro- and macroevolution is invalid? There are numerous ways, but it would be naïve to assume that evidence all of a sudden would convince a mind that is sealed airtight. However, this blog series is mainly about representing the scientific side appropriately instead of claiming ones views are right just because one tries to prove the alternative wrong. So, what does science have to offer?
A very beautiful example that visualizes the failure of the micro-macro distinction is the occurrence of ring species. Imagine a founding population of salamanders (the genus Ensatina is a well studied example) that lives at the northern end of a mountain range. Some parts of the population will spread to the right side of the mountain range and move south; some will spread to the left. This doesn’t mean of course that individuals will travel for days on end. It means that as a population brings forth offspring and grows, some individuals will move further away in order to avoid competition within the species. Within its life time, every individual only travels a few miles at the most, but the process is repeated over hundreds of generations until a huge distance is covered. After thousands of years, the salamanders will have reached areas that are hundreds of miles away from the founding population that is still at the northern tip of the mountain range. The environment and the selection pressure are different in both areas. In addition, the lack of gene flow between the founding population and its most distant branch leads to an independent development. Phenotypic differences start to occur over time. Nevertheless, every subgroup of salamanders is still able to interbreed with the subgroup in its geographic vicinity (neighboring group). So, does this example favor the creationist point of view? After all, if they can interbreed, it is still the same kind.
Remember that the founding population split into two branches – one spreading to the south on the right side of the mountain range, one spreading south on the left side. Both branches developed (evolved) independently from each other due to the physical barrier (mountains). After hundreds of Generations, both sides reach the southern end of the mountain range and come into contact with each other. Since neighboring groups can interbreed with each other, it would be safe to assume that the two reunited branches now can interbreed as well. But this is not the case. Over time, both sides have changed so much that they are now distinct species. How is that possible? Where the differences between adjacent populations were so small that interbreeding was possible, the differences between populations further apart accumulate until two groups are reproductively isolated from each other. This concept is called ring species for two reasons: first, the geographic distribution can resemble a ring like structure. Second, the transition from one group to another is fluent and cannot be dissected in distinct units. However, if one pictures a ring, be aware that there actually is a beginning and an end. The two ends are incompatible with each other so that the ring would be open. The bottom line is: it is impossible to determine where one species ends and the other one begins. Every categorization would be rather arbitrary. The beauty of this example is that it visualizes the gradual and fluent nature of evolutionary change that necessarily leads to speciation without gaps or boundaries.
Another example that renders the micro-macro distinction obsolete is a liger. Lions (Panthera leo) and tigers (Panthera tigirs) are defined as two distinct species. Nevertheless, both species can interbreed and bring forth fertile offspring – ligers or tiglons – in some cases. Such hybrids might be less fit than pure breeds and wouldn’t do so well outside zoos. However, these examples show the obvious relatedness between these two species. It might be seen as a weakness of the biological species concept when two groups that are defined as distinct species can interbreed with each other. In my opinion, it is not since science is aware of its limitations and the difficulties of categorization caused by the everlasting gradual change of living beings that we call evolution. On the other hand, what does creationism have to say about the natural relatedness of two species? Obviously, the encounter of two kinds (species) can lead to fertile offspring. I guess I already know the answer since creationists are never short of loopholes. It is still a cat they could say. Of course they are careful enough not to define “kind” precisely. It is a dishonest way of arguing: if one never makes a clear-cut statement, they can always squirm out and avoid facing the bottom of the argument. Tigers throughout Asia are all related but differ in several aspects due to what could be called microevolution. The same is true for lions in Africa. That both share a rather common ancestor is obvious. However, the processes that brought forth the differences between a Sumatran Tiger and a Siberian Tiger are supposed not to be valid when it comes to the differences on higher levels? It just doesn’t make sense to say the least.
A hyena is still a dog – or is it?
Let us consider another example that visualizes that phenotypic differences within a species can be more obvious than those between species, rendering the micro-macro distinction obsolete yet again. As mentioned in part 4, an Irish wolfhound and a pug dog would never be classified as one species if one saw both for the first time and didn’t know any better. After all, their common ancestor, the wolf (Canis lupus), doesn’t have a lot in common with either one, especially with the pug dog. All dogs are members of the taxonomic family Canidae. Bear that in mind, it will be of significance for this argument. If a wolf is compared with other carnivores, it seems to resemble a striped hyena (Hyaena hyaena) or the extinct Tasmanian wolf (Thylacinus cynocephalus) more than a pug dog. Fine, but they are still all dogs one could say. No, they are not. Despite its doglike appearance, hyenas are part of the suborder Feliformia which puts them in closer relationship to cats than to dogs. The Tasmanian wolf doesn’t even have a placenta and therefore belongs to a whole different mammal group: the marsupials.
Again, the theory of evolution has no difficulties in explaining such similarities between distinctly related species. It is the concept of convergent evolution that states that in the course of evolution different lineages can bring forth similar traits independent from each other when the environment provides the need for those structures. Bats, insects, and birds have wings, but they all evolved independently as a radiation that enabled flight. Now, if the phenotypic differences within a species (wolf and pug dog) can be more obvious than between suborders (wolf and hyena) or even placental mammals and marsupials (wolf and Tasmanian wolf), why should anyone follow the notion that the processes that shaped the variety of dogs do not apply to the variety between higher taxonomic levels? Yes, loopholes are everywhere and I can already hear creationists saying that the evolution of dogs is not a good example since it was influenced by humans. This statement misses a basic point: the potential for change was not altered by man but was already present in the wolf. Therefore, the evolution of dogs can serve as a natural example despite the obvious difference in the pace of change.
Do not trust your eyes
Among scientists who work in the field of evolutionary biology, the arbitrary split between micro- and macroevolution is not an issue. There is simply no good reason to assume that the processes that act on a smaller scale do not apply to higher levels. In the end, for critics it comes down to the common problem of “I don’t believe what I can’t see!”. If it wasn’t for those damn double standards that creationists apply all the time I could have some sympathy for their doubts. Can anyone see that the continental plates are moving? How can we know that the earth revolves around the sun? When we look up, everything might as well revolve around the earth. Does anyone see the oxygen one is breathing? Does anyone see gravitation? Does anyone see atoms? Should we not believe in any of these things since we can’t see them? It would be consistent to do so. It is science telling us that these things are real – so why apply double standards when it comes to the theory of evolution? “I can’t see, therefore I don’t believe it’s true.” Sure, creationists have a point there. It is too funny that they wouldn’t use the same statement for their own supernatural beliefs. “But I do see God everywhere!”. Yes, a statement that cannot be proven wrong – and therefore should never waste a single second of scientific effort. Hallucinations, superstition, and the tricks that our brain can play on us will be dealt with in part 18. For the time being, let us summarize this chapter: the micro vs. macro debate is what it is – a desperate attempt by creationists to justify a belief system that has been proven wrong a long time ago. Tenacity doesn’t equal truth and a false statement does not become right just because it is repeated over and over again.
Evolution – Facts, Myths, and Misunderstandings
Part 14: The Limitations of Evolution and why Nothing is Perfect
Some scientists think that all aspects of an organism have been molded by natural selection to a form optimal for enhancing reproductive success3. This approach, called adaptationism, comes with an obvious disadvantage: science would have to find evolutionary explanations for every single characteristic of a living being. Even though one can always try to find such explanations, they sometimes reach the edges of credibility and reason. In my opinion, it is far more likely that some structures are mere byproducts of other evolutionary processes than adaptations. The theory of evolution should not be understood in a way that change always leads to perfection. As mentioned before, perfection is an artificial, manmade construct that has no place in nature. It implies that nothing better could appear or happen. This is never the case under natural circumstances. Even the human eye, used as an example by creationists for perfect design, could be better in many ways. We can’t see ultraviolet light whereas other animals can. Our vision is pathetic when it is very dark. We have a hard time seeing under water and our eyes need quite some time to adjust when the intensity of light changes rapidly. We cannot even make use of the full area of our retina since the blind spot does not contain any cons and rods. If the eye was perfect, why do humans develop so many diseases regarding this organ such as blindness, glaucoma, conjunctivitis, among so many others?
No, the eye is everything but perfect. This conclusion would pose a problem for supporters of the idea that an allegedly all-powerful creator designed everything. After all, this is a reappearing pattern in creationist propaganda: everything great and amazing is mentioned as an example of great design – in this case the number of nerve cells, cons and rods and their interplay in the eye. On the other hand, everything that is flawed and bad is neglected. Again, such an incomplete evaluation is neither genuine nor honest. The flawed design of the eye, however, does not trouble the theory of evolution the least. Evolution is not about perfection. It is about being adapted well enough to survive until reproduction. No more, no less.
From the scientific point of view, several constraints make adaptive perfection almost impossible. Mutations, the ultimate source of variation, occur randomly in an unpredictable fashion. A new trait can only evolve if mutations provide the necessary information in the gene pool of the population. If the environment changes quicker than the population or if an appropriate mutation simply never occurs, natural selection will not be able to yield ideal adaptations. If the environment were stable for 1000s of years certain traits would get closer and closer to a state of perfection since there would be enough time for the needed mutations to occur. However, the environment changes all the time, causing an everlasting selection pressure where species that can’t keep up with the change go extinct. Being one step above the threshold is the rule for species rather than the exception. That is everything but perfection.
Other evolutionary processes are antagonistic in regards to adaptive perfection. Sexual selection was explained in part 6, coevolution was explained in part 7, and genetic drift or changes due to chance were explained in parts 2 and 5. Another very obvious reason why certain phenotypic traits might be byproducts was mentioned in part 8. Remember, sometimes a single gene influences more than one phenotypic trait (pleiotropy). On the other hand, a single trait might be under the influence of several genes. Such a trait would be called polygenic. Now, if natural selection favors a certain trait or a certain gene because of the advantages it offers, other traits or genes that are linked to the selected unit might be passed on to the future generations as well – as a byproduct. The chosen trait or gene might be so important for the reproductive success of the individual that the burden of unnecessary byproducts might be acceptable. Moreover, sometimes it is the interaction with the environment itself that interferes with perfection.
The well known Sickle Cell disease is a genetic defect that lowers the fitness of affected humans. A decreased amount of healthy red blood cells can cause a significant problem during times of high oxygen demand. On the other hand, humans carrying a single copy of the defect have a better chance of surviving malaria. Therefore, the amount of people which suffer from this disease in certain areas in Africa is much higher than it would be without malaria. Adaptive perfection would mean that individuals suffering from the Sickle Cell disease would be removed by natural selection in the long run, eradicating the genetic defect with them. However, this path would lead to other disadvantages which is why perfection cannot be achieved.
Wouldn’t it be ideal if a tetrapod (all vertebrates with four limbs) had an additional eye at the tip of its tail? It could see much more and increase its chances of escaping predators or competitors. Compared to related species, why are humans the only animals where the trachea and the esophagus open up next to each other? After all, several people choke to death when food or other items get stuck in their trachea. Why are there no animals that move forward on wheels? Under certain circumstances, this could be the most energy efficient way of locomotion. Why are human babies born in such a helpless and poorly developed state? What would be the disadvantage of being able to walk a few days after they were born like many other tetrapods? A creationist would have to answer such questions. If the ultimate designer is perfect, why isn’t his design? In science, of course, imperfections can be explained to a certain degree.
Evolution did not just bring living beings forth from scratch. Instead, Darwin was right when he compared the connections that link all living things with a tree. A species can only be slightly different than its predecessor. The key is gradual change and common descent. It is no coincidence that almost all terrestrial vertebrates share certain traits such as four limbs, two eyes, a neck, a spine, a tail, a central nervous system, etc. It is probable that their last common ancestor provided these characteristics to begin with. In a nutshell, evolution did not bring forth anything new in kind, but only in degree (regarding the example of terrestrial vertebrates). It is crucial to understand this point. One cannot seriously ask why evolution did not lead to the most fantastic traits when the foundations for such traits were never there. This is why, as unpredictable as evolution is, certain characteristics of future vertebrate species can be guessed. It is probable that they will still have four limbs, two eyes, a neck, a spine, a central nervous system, etc. The future of evolutionary change always depends on its past. Traits do not just appear. They are the result of a long lasting gradual change.
As a side note, the mentioned circumstance that humans can choke to death is a splendid example for byproducts that go against the idea of adaptive perfection. Apes, as well as human infants, can drink and breath at the same time since the opening of the trachea is located higher up in the throat (it moves downwards in humans as we age). Why would humans evolve in a way that we gain the ability to choke? That seems to be maladaptive. The most probable explanation is that the disadvantage of the ability to choke is a byproduct of the ability to speak. With the trachea moving downwards in our throat, the vocal cords are provided with the necessary space to produce sophisticated sounds. This (and the form of the hyoid bone) might be the main phenotypic difference that enables humans to speak in contrast to other animals. Since the Homo sapiens is a highly social animal, the ability of sophisticated verbal communication (language) might be so crucial that other disadvantages (such as the ability to choke) are more than counterbalanced.
Another critical question for a creationist would be why there are so many age related diseases. Couldn’t God have created living beings that stay healthy until they die? We can’t say that human beings today grow older and therefore are more vulnerable to diseases. After all, in accordance to the Bible the first human beings died when they were hundreds of years old. When Methuselah, allegedly the oldest person who has ever lived, died he was 969 years old. Of course, one could state that we are unhealthier today because of our way of life. This argument, however, would bring us back to the fundamental problem regarding the almighty powers of God: didn’t the creator see what humans would turn into? If he did, why didn’t he create us in a way that we wouldn’t be able to sin, that we wouldn’t have to go through diseases and suffering? If he didn’t see it coming, is he not almighty? On the other hand, the theory of evolution offers a perfectly consistent answer. The outcome of natural selection is based on reproductive success. If a heritable disease decreased the well-being of an organism before it reached the reproductive age, these living beings and the according genes would be removed by natural selection. If the disease, however, is linked to an age far after the peak of reproduction, natural selection would not weed out such genes as efficiently. After all, the genes would have been passed on to the next generation already before the disease would harm the organism. Thus, it seems likely that evolution does not counteract age related diseases.
Even though creationists would like to point out that so many things are so perfect and so amazing that natural processes could have never caused their appearance, the truth is quite different. For a vast number of traits a better version or adaptation is thinkable. Evolution doesn’t lead to perfection – but the theory never claimed that it does. Creationism, on the other hand, has to answer the question why the “design” that we see is flawed in so many ways. If creationists talk of perfection and other absolutes, they have to accept the vulnerability of such naïve statements – and researchers should be aware of such pitfalls as well. In science, absolutes should be avoided at all costs since we cannot know what the future will reveal. After all, it is this openness to change and insight that separates science from the uncritical followers of religious doctrines. No one who claims that he possesses the key to the ultimate truth should be trusted. We should be nothing but learners. The moment we bring progress to a halt we will suffer as a species. Worshipping idols and preaching questionable laws without thinking about it is one way of organizing one’s life. Being open for change and progress when evidence and reason suggests it is another.
Several more examples of imperfect design
Why do cave dwelling fish or amphibians that will never see any light throughout their lives have eyes? Why do humans have wisdom teeth which are usually removed since they might cause problems? Why do cows develop front teeth in the upper jaw as an embryo – only to lose them again before birth? Such vestigial organs pose a serious difficulty for creationist approaches since they raise the obvious question why God designed something useless. With evolution, of course, the story is different. Vestigial organs are the remnants of once useful structures which have lost their meaning. The environment and the selective pressures change – and so do species. If certain organs or structures are not needed anymore, natural selection won’t favor their existence any longer and they will degrade over time mainly due to the process of genetic drift. The ancestors of cave dwelling fish didn’t live in constant darkness and therefore needed eyes. Before bipedalism caused the lower jaw in humans to move back in respect to the skull, enough room for wisdom teeth was available. They served important functions when older teeth started to wear off. The ancestors of cows had front teeth in their upper jaws. Modern cows don’t need these teeth anymore, but due to their heritage the basic information for their development is still there. Vestigial organs are a splendid example of how a species and the function of certain organs and structures can change over time in the course of evolution. The remnants of redundant organs are good examples of imperfect design.
Why are there no mammals or birds as small as ants – and why are there no insects as big as cows? Such creations shouldn’t have posed a problem to a designer, but they do visualize natural limitations of evolutionary change. For breathing, insects depend on a system of hollow tubes that run through their bodies which is called trachea. There is no efficient active mechanism that optimizes the ventilation of the cells. Thus, the diffusion rate of oxygen through the air is the limiting factor regarding the size of insects. If they were any bigger, not enough oxygen would reach the inner parts of the body if the distance between the opening of the trachea and the cells that need ventilation would get too big. On the other hand, birds and mammals keep their body temperature high at all times in contrast to insects. In order to do so, they need a lot of energy. The smaller an animal is, the less favorable the ratio of body volume to surface is. In other words, smaller animals need to produce relatively more heat than bigger animals. On the one hand, the increased metabolic output shortens the life span of small animals. On the other hand, at some point it gets too difficult to find enough food in order to produce enough heat. Thus, the minimum size of animals and birds is limited by their need of taking up enough nutrients for their demanding metabolisms. Such explanations visualize natural limitations well.
Another thing I would like to ask an almighty creator is this: why do humans not have chlorophyll in their skin? Wouldn’t it be a great advantage to perform photosynthesis and to be fed by the never ending sun light? No more starvation, no more conflicts over food, no more suffering. Why didn’t the creator make that happen? From the biological point of view, humans can’t perform photosynthesis because none of our ancestors could. In fact, no multicellular animal can. There seems to be a natural limitation – or it just hadn’t happened yet in the course of evolution. Who knows what the future might bring.
Another example that visualizes the dependence on the structures of former species is the various kinds of forelimbs in tetrapods. After all, the same bones are either used as wings, flippers, legs, or hands. No new bones came into being during the evolution of mammals that hadn’t already been there in amphibians. Isn’t it striking that all mammals are tetrapods? Why such consistency? Why do birds or bats not only have four legs but a pair of wings in addition? Wouldn’t that be a great advantage? Why couldn’t an almighty creator have come up with such design? All species are invariably linked to their evolutionary past. Evolution means change – but only within certain limits.
The list of poor design goes on: why are our teeth so bad that our ancestors eventually were not able to eat anymore due to worn off teeth? Why, if Gods creation is so perfect, are so many species going extinct? You can’t blame it all on human influence since extinctions are well documented from times before the dawn of man. Some scientists estimate that 99% of all species that have ever lived have already gone extinct. One surviving species out of a hundred doesn’t seem to be a very flattering success rate for the creator. What sense does it make that dolphins and whales have to breathe through lungs? Wouldn’t gills be more appropriate for a marine life style? Of course, the list could be continued endlessly. However, one thing should be clear: claiming that all we see around us is pure perfection is inappropriate. Without the theory of evolution, many of the described observations wouldn’t make sense – and that is exactly why creationism fails. You cannot just pick and chose examples that suit you well while ignoring inconvenient problems. That is not how science works. Evolution has its limits – and so does creationism. As soon as it leaves its comfortable habitat of superstition and denial by trying to influence science or politics, it is not only an insult to the human mind but also a threat to the foundations of progress and enlightenment that our societies should be based upon.
Evolution – Facts, Myths, and Misunderstandings
Part 13: Evolution, Morals, and the Purpose of Life
Frankly, I believe that those people who rally the most against the theory of evolution and certain scientific concepts do so for two reasons: first, they are afraid that their church will lose the power that it has always had and which it has used to utilize and manipulate people in many ways for centuries and second, I think – and this applies more to the average Joes – that many people are genuinely concerned that a life based on science without God will lead to an erosion of morals and virtues. The first point will never be admitted, even though it is rather obvious in some cases regarding, for example, the prosecution of freethinking scholars during the inquisition. For the most part, the church has already lost its authority regarding astronomy, history, and many natural phenomena that can be explained today. It therefore clings even more to what is left– the origin of the universe and life and the exceptional role of human beings.
The second point, however, is one that is openly admitted through questions such as: “If God didn’t create us, where do our moral standards come from?” Moreover, the religious opponents of the theory of evolution like to point out what “Darwinism” has brought forth the worst atrocities mankind has had to witness through Hitler, Stalin, Pol Pot, Mao Zedong, and others. There are so many things wrong with such statements and accusations that a lot of explanations regarding scientific intentions and limits are required to show how absurd these correlations are. In addition, such propaganda falsely assumes that the theory of evolution equals atheism. This connection will be considered later in this article. First and foremost, scientific principles and intentions shall be explained yet again in order to clear up misunderstandings.
How does science shape our morals?
If a person blames science for moral failures or acts of a human being there is one message that needs to be remembered after reading this blog: science describes how things are, but it never tells us how things ought to be! Science is only descriptive – no more, no less. A scientific statement can never give any advice whatsoever. If a lion takes over a new pack, it is likely that infants will be killed. Does such an observation contain any moral values and does anyone suggest that stepfathers should do the same? We now know that certain ant species utilize other species as their slaves. Would we accept slavery based on biological explanations in human beings? Promiscuity is widely spread in the animal kingdom, but a human partner that was betrayed will certainly not accept such an explanation as an excuse. Again, for dubious reasons, different standards are applied to the theory of evolution than to other branches of science. Remember the definition of a theory from part 11. A theory is a scientific construct that tries to explain natural processes. With or without the description, the process will go on. Blaming someone for giving it a name is absurd. If someone fell off a building and died due to the impact that gravity had on his acceleration, would anyone blame Newton for coming up with the theory of gravity?
Science does help us figure out what certain things do and cause, but mentioning the fact that smoking is bad for one’s health and telling someone not to smoke are two very different ideas. The one is just a neutral description of what is probably going to happen. The other is a statement of advice or even law. Thus, it should be obvious that science itself would never suggest any action – only the person interpreting the results does. A scientist can say that people shouldn’t smoke since his research shows that it is harmful. However, these results do not provide the researcher with any moral authority whatsoever. This point is so essential that it can’t be stressed enough: science describes how things are. Under no circumstances could a description be moral or immoral. It is humans who decide what they want to utilize in order to justify their actions.
One of the most popular examples regarding the misinterpretation and false utilization of science was “Social Darwinism” which was applied, besides others, by the Nazis in Germany during World War II in order to justify the murder of Jews, gypsies, handicapped people, and other individuals that were deemed unworthy. This belief system was rather a cult than proper science and even if science had stated that some human beings were superior over others, it wouldn’t have suggested the eradication of the weaker individuals. In fact, we know today that science states the opposite due to the work of Luigi Luca Cavalli-Sforza. Genetically, all human beings are so closely related that there is no foundation whatsoever for distinguishing different races. It is impossible to avoid that certain individuals manipulate facts and distort intentions for their own benefits. However, it is essential to understand that no serious scientific book exists that would tell people how to behave. Therefore, if something evil is done it cannot be done in the name of science. It is as moral or immoral as the weather forecast, a history lesson, a dictionary, or any other example where certain aspects are simply described.
What does science tell us about the purpose of life?
What is the purpose of comets, hydrogen bonds, or earthquakes? Does erosion or rivers intend to shape canyons? What is the purpose of the rotation of our planet? Most people wouldn’t ask for a purpose or for goals regarding these scientific observations. The question is then: why aren’t they consistent and accept that likewise the question for purpose, or for goals, is also unnecessary when considering the theory of evolution or life itself? Why use one way of looking at science with some topics and another one with others?
Scientifically, there is no higher purpose to life than reproducing and spreading one’s genes. Should we be depressed and lose our joy in life since there is nothing to live for? If that is one’s attitude, I am sorry. The simple truth is that everyone will have to find one’s own purpose in this world. However, I am rather repelled by the religious notion of purpose. After all, everything a religious person does is selfish. Why? First, they want to “impress” their maker in order to make it into heaven. Therefore, everything they do is motivated by this one overarching goal. If they do something good, they hope it will be rewarded later. Second, human beings want to be loved. They want to be on earth for a purpose. They want to be the beloved child of a creator that has something planned for them. They do not want to face the possibility that they are unimportant and alive for no particular reason. In order to get constant reassurance, they love themselves by being convinced that they matter. This is nothing but narcissism – a very selfish characteristic which people usually are not aware of.
It is a simple truth that science by definition cannot provide any purpose. Neither evolution, nor the earth, nor the entire universe or anything else cares that we are here. After all, about seven billion people don’t even care that you or I are here right now – who grieves for the approximately 30,000 children who die every single day due to starvation? I guess God has a plan for them as well and loves all of them so much that he can’t wait to take them to him. However, the main point here is that looking for the purpose of life in science is completely senseless. As stated above, there is no intention or higher purpose in the world. Every individual has to decide him or herself what he or she wants to do with what they were born with. However, it seems to be nobler to be grateful and humble for being alive despite the odds (see part 12) instead of thinking that one is important and put on earth for a reason.
So, if science can’t give us a purpose of life, what can? The easiest way would certainly be religion. Heck, one wouldn’t even have to think much for oneself. It would all be laid out and documented in scripture and dogma. The purpose of life is to do this and that because someone says so. Understandably, many theists will disagree with this point, but when it comes down to it their purpose of life is to make it into heaven. Everything else that comes with it is a mere side effect of the ultimate goal. Some religious fanatics will underline that point when they threaten people who do not do what they “should” do with eternal suffering in hell. Yes, religion provides a clear purpose – but it is not a desirable one in my opinion. Atheists, on the other hand, have to define a completely different realm of goals since they lack the prospect of an afterlife. First and foremost, I am an atheist myself, but the following statements do not intend to make any evaluations over more or less moral attitudes. I have a reason why I do not like the purpose religion offers. However, claiming that my motivations are morally superior would be arrogant. I am going to name them in order to answer the question a theist might ask: “Without God, what do you live for?”
What does an atheist live for?
In order to avoid confusion and misunderstandings, one thing needs to be cleared up first: a person who supports the theory of evolution does not necessarily have to be an atheist. There is no ultimate connection between the two. I don’t understand why so many fundamentalists regard evolution and atheism as inseparable units and thus do not distinguish between them when formulating superficial judgments and accusations. Although more atheists are found among scientists than among other groups, many researchers are still theists. For some, evolution and everything else are natural processes, but a supernatural being put everything into place and started it. They have no problem at all with combining both, religious belief that offers moral guidance and the acceptance of science. As stated above, science doesn’t offer any moral guidance, so people have to get it elsewhere. Nevertheless, what are people living for who do not believe in any supernatural forces?
I, for my part, try to avoid that I will wake up one day thinking: “What have I done with my life?” Regret is a strong force and avoiding it is a strong motivation. Starting with that simple statement, I try to think of what might make me happy at the moment and proud later in life. I have accepted that I influence this world since it is impossible not to do so once one comes into being. Many people say that they are not doing certain things because their efforts won’t count (because one person can’t make a difference). In my eyes, they are too cowardly to accept their own responsibilities. I don’t eat meat because I don’t want to be responsible for the deaths of innocent beings just because I like their taste. I don’t buy clothes which were produced by children under terrible conditions. I usually don’t buy fruit or vegetables that had to be imported from overseas since I don’t think it is useful to waste the fuel and add up to the already existing pollution. I support human rights groups by signing their petitions. I only use recycled toilet paper since it seems to be so redundant to me to cut down trees just to flush them down the drain.
None of these points are of major significance if they stand alone, but it is the big picture that counts. I am thinking about the influence that I have in this world so that I can at least say that I have tried my best with a clear conscious. Most importantly, I see a purpose in life in how we treat other humans and living beings. If my girlfriend is happy due to my influence, I have found a great purpose for my existence. The same is true for my family, friends, or anyone else who I could help. It is honest gratitude that makes life beautiful and that gives it its meaning. I couldn’t be happy if everyone around me was miserable and having someone thank me dearly is one of the greatest rewards imaginable. If more people defined their happiness through the happiness of others – what a wonderful world we would live in. Even though it is not always easy, I am trying the best I can to be friendly and polite towards others as long as they deserve it. Why? Because life is so much more fun when people are nice to each other and how could I genuinely expect others to treat me well when I am not the one setting a good example? In short, my purpose of life is to make this world a better place by making conscious decisions. If the life of at least one person benefits significantly from my existence on an emotional level, I have achieved my goals. It is that simple. I don’t believe in an afterlife, so after my death I will become one again with nature. Until then I will try to make life on earth a little better. As with love and friendship, it is not big things that matter – but an infinite amount of small things.
Morals without religion
I still haven’t given an answer to the question where I am getting my morals from. If I am trying to make life for someone else better, what defines better or good? Even though I do not think that biological explanations should be used in an effort to explain every single detail of human behavior, I do think that science offers some powerful insights into why we do and think certain things. A particular train of thought that seems to be obviously guided by our instincts is the concept of group mentality. Sure, a sociologists could stop me right there, pointing out that such behavior is due to social circumstances. Nevertheless, if certain behaviors are found among any human group around the world and even in many animals, society does not seem to be the most important factor.
A basic characteristic of group mentality is the principle that different standards apply for members of the group than for those who are not part of the group. Soldiers in civilized countries or warriors in indigenous people will kill their enemies on the battlefield without hesitation if they have to. They would never be as ruthless regarding members of their own army or tribe. People are longing to be in groups or clubs, no matter if the topic is sports, politics, activist groups, or others. Every time the same pattern can be observed: people treat members of their own group in a different way than they would treat “outsiders”. When human beings perform the most atrocious crimes it is an established group mentality that reduces inhibitions. The members of the Schutzstaffel (SS) became known as the single most merciless killers during World War II, trying to eradicate certain groups of people such as Jews and gypsies. However, many of them were known as loving fathers and husbands. During one of the worst genocides mankind ever had to witness, about 20% of Rwanda’s population was killed when the Hutu tried to extinguish the Tutsis in 1994. In Iraq, thousands of Kurds were killed by Saddam Hussein and his henchmen while Muslims died in an effort to “cleanse” Bosnia in 1995. Some scholars such as Daniel Goldhagen, a former political scientist at Harvard University, even claim that genocides caused more deaths in the 20th century than all wars combined. Many more examples could be mentioned but they all show the same pattern: it is easier for a human being to commit atrocities when one is following the image that the enemy is part of another group which does not have the same rights and values. What is true for such big cases is also true for every day encounters. If a member of your team or group behaves like a jerk, the group members are likely to turn a blind eye. If a member of another group behaves comparably, the reaction is not quite the same.
From a biological standpoint such behavior makes sense. For the majority of human history, cooperation between group members was essential. In a daily struggle for existence it was inevitable to fight other groups in order to maintain resources. This kind of behavior is seen in chimpanzees as well. It was Jane Goodall who was the first to witness systematic attacks of one group towards another including killings. Eventually, the weaker group ceased to exist – the “genocide” was complete. On the other hand, conflicts within the group rarely result in serious injuries. What is the point of all of these examples? The point is that our biological past offers some explanation for why human beings are good on the one hand and bad on the other. Without altruism or selflessness within the group it seems to be impossible that a species as social as our own would have survived in the past. However, since competition is everywhere the group mentality is ingrained in our species: my companions and I come first. I cannot bother as much about things that happen outside my group. If a plane crashes and 100 German citizens die, every news station will be all over it. How much do Germans care when 30,000 Pakistanis die in a devastating earthquake? The USA is in shock for years after terrorists killed about 3,000 of their citizens, but how many Americans care that the wars that they unleash kill many more innocent people? Would an Islamic terrorist run amok in a mosque? Group mentality is strong within our species and one of the biggest challenges for the equality of all human beings.
Nevertheless, my answer to the question where I would get my morals from is much more than just saying moral or good behavior proved to be beneficial in the past (within the group) and was therefore maintained throughout evolution. Society also plays a very big role in shaping our morals and ethics. After all, some people think it is right to stone people to death or to degrade women as lower human beings which have to obey men. Western states usually disagree with such an attitude and raise their children in a different way. The most important foundation for morals should be reason and compassion. I do not want to cause other people discomfort for no reason since I wouldn’t appreciate if they did the same to me. However, even the golden rule has its limitations and can be harmful if applied without reason. Some people get joy out of the weirdest things, such as licking someone’s feet. If a person with such a fetish would obey the golden rule, he would make another person lick his feet. I doubt that both sides would enjoy such an encounter equally. Reason in this sense means that one should think about what could be good for another person. The Human Rights Charter offers a good example of a secular guideline for morals. Even though it might have its limitations as well, its foundation is the equality of all human beings which is not always found in alternative moral guidelines. Still, how can a pamphlet teach morals? It doesn’t directly, but it can make people think about what every single human being deserves and what one can do in the name of justice. When born, no human being is more important than another one and everyone should have the right to live happily and freely as long as the basic rights of others are not restrained.
Finally, to cut a long story short, I think that I got most of my sense of morals from my parents since they are good people. In addition, as with my purpose of life, my morals are guided by the principle that I am horrified by the idea that I will regret things deeply when I am old. After all, as an atheist I wouldn’t have a loophole to get rid of my burden. Maybe this awareness makes me think harder about my own actions since no one will offer any relief afterwards.
What is the alternative?
As mentioned above, I am rather appalled by the moral foundations religion has to offer. Who tells a Christian that it is wrong to molest children, to have slaves, to rape women, or to have sex with your mother? The Ten Commandments don’t – not to mention the atrocities committed by God in the bible. A genuine fundamentalist would have to believe that it is ok to stone their wife to death when she has committed adultery or to punish people severely when they are working on the Sabbath. Many things the Bible demands would be immoral by any rational mean. Fortunately, most Christians do not obey such orders – but why? What tells them that it is wrong? In the end, it is a secular society that determines that actions are not automatically right just because they are performed in the name of religion. After all, without secularism the sick Christian cult of human sacrifice that worships a symbol of torture and death could yet again turn a courtyard into a burning stake. However, what sickens me the most about a religious person questioning my morals is the ultimate deduction. If they claim that atheists behave worse and might commit crimes just because they do not obey a supernatural authority, do they themselves behave morally just because they are afraid of being punished for misbehavior rather than being convinced that certain acts are simply wrong? If they get their morals from God and religion, would they just go around and kill and rape the hell out of the world if God wasn’t there? That is moral failure and I want no part of it.
Furthermore, what was God thinking when he created everything? Why is there so much pain and suffering in his creation? Why did he create carnivores, introducing a whole new level of killing and misery? Why did he create bed bugs (see part 6) where all males rape the females by piercing their copulatory organs through the abdomen of their partners, ejaculating into the body cavity? Why did he create lions that kill cubs when they take over a new pack? Why did he create certain species of insects and spiders where the male is eaten after sex? There are so many things in the natural world that seem to be immoral if one assumes that a moral authority is behind everything. Of course, a theist could use the ultimate loophole and claim that God works in mysterious ways. In addition, a believer could say that animals are animals and we shouldn’t try to look at them from the standpoint of human morals, justifying any atrocity a human being could commit to nature or another living being. The problem is: if animals are meant to be inferior and humans can do with them whatever they want, why did God give them the ability to feel, to think, and to suffer? Oh merciful God, are you morbid or just imperfect?
Evolution in school
Finally, a few words shall be mentioned about the role of evolution in public education. Many creationists demand that the theory of evolution and creationism should both be taught in science class. Listen up creationists: religious claims are beyond the reach of science. Neither the existence of God nor his absence can be proven empirically. The scientific method applies to no parts of creationism. Therefore, it has no place in a science class because it is everything but scientific. If it wasn’t so important and wouldn’t influence the minds of future generations this debate would be nothing but annoying and tiresome. Why should a theologian influence the scientific curriculum? Sure, creationists could claim that some scientists have doubts about the theory of evolution which is why their alternative should be represented equally. However, even if one could prove A wrong, α wouldn’t be necessarily right. It remains an absurd claim (that doesn’t even deserve the metaphorical B) that is not backed up by any evidence. There are some historians that claim that the Holocaust has never happened. Should they be able to represent their ideas in history class? Such thinking is nuts and needs to be removed from public education as soon as possible.
In the end, religion always has the advantage. Believing in things without questioning them just because one has been told to do so is much easier than properly understanding science. This is why religion is so powerful and attractive to the masses. Not everyone gets science, but it is easy to get religion. It offers comfort and reassurance that soothes the people and it doesn’t even have to make sense all the way. It is the easy path for people who might have a hard time finding a purpose in life for themselves. The sad thing is that no matter how many times religions are wrong or how many times bad things happen in the name of religion (wars, fraud, child abuse, etc.), the people will fall for it again and again. It is that which makes me doubt that we are a highly evolved species after all. People want to believe so badly in something that they forget that things aren’t necessarily true just because they really want them to be.
Evolution – Facts, Myths, and Misunderstandings
Part 12: Evolution and Probabilities
One of the biggest trumps of creationists in a debate seems to be the argument of fine-tuning. If various forces in the universe were only slightly different, life as we know it couldn’t exist. It seems to be so improbable that the right chemicals came together at the right time under the right circumstances in order to enable the origin of life. Another example that is commonly mentioned is the fascinating complexity of the human eye. How could such an elaborate structure evolve even if time was not an issue? Thus, scientists who believe that it evolved from simpler forms have to have at least as much faith in their convictions as creationists do. Finally, there is the argument of irreducible complexity. Even within a single cell structures and biochemical pathways are so complex that they wouldn’t be able to function as a whole if a single part was missing. How could it have evolved that way? You have to have all of these developed structures appear at the same time in order for the machinery to work. Gradual changes won’t do it. It has to be designed as a whole – like a mousetrap, that wouldn’t function if any of its parts were missing. One by one, these points will be discussed and the creationist alternatives will be refuted, starting with why the argument of low probabilities questioning the theory of evolution is obsolete. One of the examples used to make the point will be a rather scientific one which might only be understood in detail by readers with a basic understanding of biochemistry. The first example, however, should be comprehensible enough for non-scientists as well.
Probabilities and inconsistent trains of thought
When talking about probabilities, creationists like to put numbers on the table which are supposed to prove that certain assumptions necessary for the validity of the theory of evolution are so improbable that it would be irrational and against common sense to believe that science is right. They never explain how they have calculated these numbers of course since calculations regarding probabilities are highly speculative. After all, are probabilities something one can measure on a common scale? Instead, they try to use visualizations such as: “This number is even bigger than the amount of grains of sand on earth”. What they don’t see – or what they deny since denial is what they are best at – is that they turn this argument completely around when it comes to other topics such as the probability of events described in the bible or contemporary superstition.
Take homeopathy as an example. Homeopathy works in some cases due to the placebo effect. It is pure superstition and rather believed by people with a religious background than by scientists. Why is it a hoax? Because the compound that is supposed to cause the positive effect is diluted so many times that in the end statistically there is not even a single molecule left. The bottle one buys is pure water. If one knows how many molecules a liter holds (6,022×1023) and how often the original mixture is diluted (at least 24 times 1:10), this is actually a rather simple calculation. Defendants of homeopathy will then argue of course that the water was influenced by the compound – that it has a memory. Besides the simple fact that nothing we know today about biology, chemistry, or physics suggests that this is possible, it makes even less sense when one thinks about the never-ending circle of atoms in nature. Some scientists have calculated that every human being alive today has inhaled at least one of the atoms which were part of Julius Caesar’s last breath. In that sense, some molecules of the water we drink were part of somebody’s urine at some point in the past; they were inside a human being with a fatal disease; and they were part of the vomit of a sick or drunk person. Does water remember that as well?
Now, I might be wrong but I assume that there is a correlation between believing in conservative doctrines and believing in such “alternative medicine”. How is it that someone who wants to use rational mathematics in order to disprove science on the other hand believes in something even though rational mathematics has proven it wrong? It seems to be too much to ask for certain people to be consistent and genuine. If it suits them, facts and words are distorted until they achieve what they want. If their lack of credibility is due to a lack of knowledge or rather due to denial remains their mystery. However, let’s consider the argument of low probabilities in more detail. If creationists claimed that certain things could not have come into being by natural means because the odds were too slim, I claim that they as an individual could not have come into being naturally for the same reason. The improbability of their own existence is a splendid example for why low probabilities do not equal impossibilities.
The fallacy of using calculated probabilities
Geneticists assume that every single egg in a women and every single spermatozoid in a man are genetically unique (why that is will be explained below). Already, this should make one think. Every human being (except identical twins) is unique due to its genetic makeup. If the genes were different, so also would the individual be. How many eggs and spermatozoids are there? Women are born with about two million immature eggs out of which only a few hundred will mature later in life. This is the first number to remember. Every other egg than the one a person originated from would have lead to a different human being. Thus, the odds that the one egg that was chosen developed into a person alive today were 1:2,000,000. As we know, sperm is on the other side of the equation. In contrast to women, men are not born with their spermatozoids. When boys hit puberty, sperm starts to be constantly produced independent of the amount of sex one has. With every ejaculation at least 100,000,000 spermatozoids are released. Only one of those succeeds in fertilizing the egg (except in polyzygotic multiples). Again, every single spermatozoid is unique. Every human being is the result of a certain spermatozoid reaching the egg first. Here, the odds are at least 1:100,000,000. If both probabilities are combined, the odds of the right egg and the right spermatozoid coming together are 2,000,000 times 100,000,000. But this is not the end of the story. Remember, sperm is constantly degraded and produced in men. Therefore, there is only a very limited time frame for the right sperm to enter the women. Every other sexual event would have released 100,000,000 different spermatozoids. The same is true for the woman. Since eggs mature monthly, this one particular egg that lead to a certain human being was only available for a short amount of time. The probabilities of the right timing are already so low and uncertain that they can hardly be measured with mathematical equations.
In addition, the life style of one’s parents alters the quality of their eggs and sperm, which is another factor that influences the uniqueness of every living being. If circumstances during the production of the sperm or during the maturation of the eggs were different, one would probably not be here at the moment. Furthermore, we are more than just the result of our genes. As mentioned in part 8, epigenetic factors influence our development considerably. Again, if circumstances would have been slightly different, the individual considered wouldn’t be here today. The list can be continued almost endlessly, for example regarding the odds of one’s parents having a child together and not with somebody else or everything that happened in the history of one’s family and species. An uncountable number of circumstances had to be met throughout time in order for a certain individual to be alive. It wouldn’t make much sense to continue further, but one thing should be clear: if the odds for the existence of any living being are transferred into mathematical terms, they would be one to a number that is much bigger than the amount of molecules in the whole universe. Thus, if one accepts that he/she came into being by natural means, they also have to accept that life in general could come into being by the same means despite low probabilities.
The argument of low probabilities is obsolete and can only be applied if one thinks that there is a reason or purpose behind everything. “I am here – Therefore there must be a purpose.” The self-loving conviction that one is important and indispensible is nothing but narcissism. After all, if it wasn’t for the right egg and for the right spermatozoid, one couldn’t think about it since he or she wouldn’t exist. Why is that so hard to understand? Uncountable numbers of life forms and stars can’t be bothered by the question why they don’t exist because they never came into being. If circumstances wouldn’t have been right in the past, life as we know it wouldn’t have been able to develop and we wouldn’t be here asking such questions. That we can ask these questions does not to the least qualify us for the notion that we are special and here for a reason. The fallacy that morals can’t exist or that there would be nothing to live for without an ultimate purpose will be dealt with in part 13. For now, remember that big numbers are not a scary trump in the hands of creationists. Sure, they could say that Gods plan was for them to be born – but why send millions of eggs and spermatozoids which could have produced life as well to their certain end? Again, that is poor creation.
The uniqueness of gametes (Note: I might work on this paragraph again for the sake of comprehensibility after I have finished uploading all parts.)
In order to back this argument up, the statement that every egg and spermatozoid (gamete) is genetically unique has to be validated. As mentioned in part 1, the DNA of a human being is stored in every cell (except cells without a nucleus such as red blood cells/erythrocytes) in the form of 23 pairs of chromosomes. These chromosomes are only visible under the microscope during the generation of gametes (meiosis) or when the genetic information is duplicated during the split of a cell into two daughter cells (mitosis). Mitosis occurs within our body everywhere at all times. No cell lives for a human lifetime without dividing. Even the cells constituting our bones are being replaced after several years. This, in fact, is one of the reasons why we age. A copy can never be better than the original.
If the DNA is duplicated, two major problems occur: first, every copy is prone to errors (mutations) and second, with every copy the ends of DNA (telomeres) are shortened until they are degraded to such an extent that eventually important parts of the DNA are only partially copied (to explain why they are shortened would go too far). Mitosis, however, is not the reason for the uniqueness of eggs and spermatozoids. Gametes are produced through the process of meiosis. Where the DNA is simply duplicated during mitosis, the genetic information is shuffled during meiosis. For mitoses, the cellular distribution of chromosomes inherited form father and mother doesn’t change. In other words, the 46 chromosomes are simply split in half. Every daughter cell then contains 23 pairs of half chromosomes (chromatides) which are duplicated in order to reach 23 full chromosome pairs again. In meiosis, however, the recombination of the chromosomes is the key to diversity and one of the main advantages of sexual reproduction. It is important to understand that mitosis begins and ends with diploid cells (cells with two sets of chromosomes). The results of meiosis, gametes, contain only one set of chromosomes. Here, at a certain stage the chromosome pairs are separated instead of just splitting the chromosomes into two. Remember, one half of your DNA (23 chromosomes) comes from the father and the other half comes from the mother. Chromosome Ifather is the equivalent of Chromosome Imother which is why both come together as a pair inside the nucleus of the cell (they are homologous). The same is true for the other 22 chromosomes.
As an example: in a random sampling mechanism during meiosis 17 chromosomesfather and only 6 chromosomesmother could end up in a one gamete. Theoretically, the ratio could be anything between 23father:0mother or vice versa. Even though chromosomex is similar in both parents, the DNA of father and mother is not identical since several differences exist. Thus, which traits end up in which gamete is decided during the division of the chromatides. For example, if the gene for eye color was located on chromosome VI and the gene that influences the structure of the teeth on chromosome XI, one could inherent eye color from the mother and the teeth structure from the father if the respective chromosomes end up in the same gamete. This is where math comes into play. If 23 pairs are divided and every pair constitutes two alternatives (DNA from father or mother), 223 different genetic combinations are possible. In other words, theoretically 223 gametes have to be produced before two share the same genetic makeup. The real diversity of gametes, however, is much bigger than that.
When homologous chromosomes come together during meiosis, they can exchange parts of DNA with each other. This process is called recombination and it is one of the major processes leading to genetic diversity. As a result, a chromosome that was derived from the father will turn into a hybrid of maternal and paternal DNA. Remember, in any chromosome pair one chromosome resembles the DNA of the mother and one the DNA of the father. In order to visualize it, imagine that the maternal chromosome is blue and the paternal chromosome is red (both are X-shaped). During recombination, both will exchange parts at the same (homologous) location. In the end, the blue chromosome got a red “foot” and the red chromosome got a blue “foot”. Since crossing over events can happen multiple times in any chromosome pair, it is virtually impossible to calculate all the possible outcomes of different genetic varieties. The differential distribution of chromatides and recombination explains why every gamete a human being produces is genetically unique. It is also important to understand that this diversity is one of the major prerequisites for evolution. Without diversity, natural selection couldn’t be at work.
Another explanation why all gametes are unique can be found here:
The odds for proper protein folding are another example that weakens the argument of fine-tuning and that visualizes why there is more behind developments occurring in nature than just the calculation of probabilities. However, some knowledge of biochemical principles might be necessary in order to understand this example properly.
Proteins are synthesized at ribosomes as chains of amino acids. Two amino acids are linked via a peptide bond which is planar and which shows a double bond character. That means that the nitrogen and the carbon atom which constitute the peptide bond cannot rotate with respect to each other. The atoms constituting the adjacent bonds, however, can. The respective rotation angles are called phi (N-Cα) and psi (C-Cα). Proteins are not linear constructs, but elaborate three-dimensional structures. The ability of the atoms to rotate in respect to each other is crucial for proper protein folding to occur. Nevertheless, not all rotation angles are possible due to steric clashes between atoms. Two atoms can simply not be at the same place at the same time. This lowers the number of possible conformations considerably. The Ramachandran diagram visualizes which values for phi and psi are possible.
The proper folding of the amino acid chains is crucial for the protein to function. The question is: what guides protein folding? If the approach was simplistic and took only math into account, folding would be way too slow to be realistic. If a protein consists of 100 residues (amino acids) and each residue could assume three different conformations (in regard to phi and psi), 3100 structures would be possible. If it takes only 10-13 seconds to convert one structure into another, the total search time would be 5×1034 seconds or 1.6×1027 years. The enormous difference between calculated and actual folding times is called Levinthal’s paradox2/p.68. Thus, if protein folding was a process of random search or trial and error, no protein would be folded properly in time. In creationist terms, proper protein folding doesn’t occur since the odds are too low.
So, how does protein folding work? It is essential to understand that the information for the three-dimensional structure of a protein is conserved in its primary structure (sequence of amino acids). It is known that certain proteins (chaperones) assist the folding of others, but even without chaperones the enormous difference between calculated and actual folding times can be explained. The specific side-chains of any amino acid interact with the side-chains of other amino acids and with the environment by either attraction or repulsion. This is a favorable process, since a folded protein is more stable thermodynamically. If a part of the protein has reached its most stable position, it will stay that way instead of rearranging the protein as a whole until every amino acid has reached its most stable position. This is called cumulative selection. Metaphorically, protein folding can be depicted as a funnel shaped process. At the top of the funnel, many structures are possible. With every established bond, however, the funnel becomes narrower with each step until the whole protein has reached its proper folding stage. The funnel is rather steep – intermediates are unstable and do not accumulate. Moreover, if some parts of the protein have reached their most stable position, other parts that are not properly folded yet will be attracted and “guided” in place. Thus, protein folding is a highly cooperative process that accelerates with time.
It can be said that the essence of protein folding is the retention of partly correct intermediates2/p.69. Why is that important? Because it makes a very important point about natural processes in general. It is obsolete in many cases to argue that the odds for certain natural processes are too slim to actually occur just because one calculated a number. If probabilities explained everything, any individual could impossibly come into being by natural means and a single protein could not be properly folded in the lifetime of a human being. As explained in this issue, probabilities are only one part of the explanation. In the process of evolution, just as in protein folding, favorable intermediate states accumulate. It is simply a fallacy to assume that certain structures have to be in place all at once in order to function. Yes, if the human eye lacked certain parts such as the retina it couldn’t function properly. However, that does not mean that there aren’t simpler organs in other animals used for the recognition of visual cues.
The fallacy of irreducible complexity
The argument of irreducible complexity is flawed since it simply ignores the pre-existence of simpler forms. A creationist might say: “If the engine of a car is removed, the car as a whole is useless.” Yes, that is true, but as explained in more detail in part 17, there are two major problems with this train of thought: first, it is fundamentally inaccurate to compare the development of living and non-living things and second, a car without an engine might be useless, but bicycles have been used as a more primitive means of transportation before the invention of cars. As it seems, the car is not so irreducibly complex regarding its task after all. Similarly obsolete is the argument that the existence of certain natural structures could be compared to the odds of a tornado assembling a plane just by chance. I would indeed not believe that such an event was possible, but this has nothing to do with evolution or the existence of the universe. Regarding natural processes, there are always “funnels”, such as natural laws (e.g. gravity, thermodynamics, kinetics, and others) on the one hand and guiding, non-random processes such as natural selection on the other hand.
It cannot be expected that everyone is familiar with scientific principles. However, it is surprising again and again that people with an obvious lack of scientific knowledge speak out loud against science in public. In order to deliver another argument for the obsoleteness of the notion of irreducible complexity, enzymes can serve as another biochemical example. It could be stated that the odds for the right amino acids to occur in the right order are too slim too evolve. After all, the enzyme can only function if its three-dimensional structure is developed appropriately. As a side note to begin with, enzymatic process can be catalyzed even in the absence of proteins by single stranded RNAs. Comparable to proteins, the primary structure (nucleotide sequence) of the RNA contains the information for its three-dimensional form. It is likely that catalytically active RNAs (ribozymes) were the first catalysts of ancient life forms. Regarding proteins, the odds for a proper amino acid sequence to evolve are not as slim as stated by some critiques. Again, doing nothing but calculating probabilities is too simplistic and misses actual circumstances. In fact, enzymes that share only 20% or even less of their amino acid sequence can perform the same task. Why is that?
It is important to understand that many amino acids within a protein are of minor importance and dispensable. Only the amino acids constituting the catalytic core of the enzyme are not as flexible and more conserved (they change less over time). However, conservative substitutions (the exchange of an amino acid with another amino acid with similar properties) are possible and wouldn’t alter the function of the protein. As a result, protein variation in nature is extensive. Some enzymes even developed independently and now perform the same task. The key is the three-dimensional structure which is more important for the functionality of an enzyme than its amino acid sequence. Today, it is even possible to simulate molecular evolution. The result can be different molecules with similar three-dimensional structures that are all equally suitable for a certain task that guided the selection process. For more details, please review source #2, page 184.
Another example is the process of splicing. In eukaryotes, introns have to be removed (spliced) before the mRNA can be properly translated into sequences of amino acids at the ribosomes. The remaining exons are connected to each other and exported from the nucleus into the cytosol. The spliceosome, a complex assembly of proteins and small nuclear RNAs (snRNAs), is usually responsible for splicing immature mRNAs within the nucleus. So, how could such an assembly evolve step by step if every single part is needed for the process of splicing? Single celled organisms (Tetrahymena) are known where the mRNA can remove introns by itself, meaning that it can splice itself in the absence of protein2/p.804. Again, the over-simplifying idea of irreducible complexity would miss the point that biological structures today might indeed be irreducibly complex, but they have evolved from simpler forms. Comparably, ancient translation mechanisms (protein synthesis) probably worked in the absence of protein which seems to be indispensible today. After all, the catalytic function is carried out by the ribosomal RNAs (rRNAs), not by the protein subunits providing the structure of the ribosomes.
The bottom line is that the arguments held up against the theory of evolution usually crumble when science is studied in more detail. Curiously, even some scientists accept certain aspects of the theory of evolution and reject others. It goes without saying that not all scientists are atheists. However, I will probably never understand where a theistic scientist draws the line between thinking critically and believing faithfully. As an example, when I worked on my diploma thesis in biochemistry, I had an argument with my advisor once about evolutionary explanations. He rejected the notion that many characteristics that exist today, especially behavior, could be explained by the theory of evolution. I did not think of it at the time, but the contradiction in his statement was that biochemists rely on evolutionary explanations all the time. If a certain structure is found in several molecules, scientists are convinced that it is crucial for a certain function even if its role has not been determined yet. Why do they assume such a functional role? If the structure wasn’t important, natural selection would have caused its loss over time. Thus, it was shaped by evolutionary mechanism. This is evolution on the molecular level. Most of my advisors work was based on the theory of evolution even though he might not have even been aware of it. Why so many people admit that evolution works in small realms but deny its impact on a larger scale will remain a mystery to me. Apparently evidence can be so overwhelming that some do not see the wood for the trees.
Evolution – Facts, Myths, and Misunderstandings
Part 11: Evolution is only a Theory and not a Fact?
Yes, that is indeed the case. The theory of evolution is not a fact, it is a theory. Should this bother anyone? No, of course it shouldn’t. Yet again, in their desperate search for weaknesses of the theory of evolution, creationists cling to arguments that no one would use if certain scientific principles were properly understood. First of all, there are no facts in science. Even though not all scientists might agree on this point, it is an important one in my opinion. As mentioned in other parts, science is a process, not a result. It is the prime example of development and change. If new discoveries question accepted assumptions, the scientific community has to rethink its definitions. Science is a self-correcting process of doubt and investigation that doesn’t exclude errors, but that corrects these mistakes in the long run. There is no place for facts in this realm. After all, a fact is something that is not questioned anymore and accepted as the ultimate truth. It doesn’t work that way in science. As with perfection, the idea of facts is an artificial construct that can only apply to something manmade. So, yes, there can be facts in religion or politics, since these areas and the circumstances necessary for definitions are manmade. In science, however, nothing should be accepted as the ultimate truth that will never change. There is no scientific progress without doubt – and that is not a bad thing.
Another point that is usually not considered when creationists try to degrade evolution as “only a theory” is that all the other things we believe in are “only theories” as well. There is the theory of gravity, the theory of quantum mechanics, the theory of relativity, etc. All of these are “just theories”, but does anyone not believe in them? Here is the thing: scientists are trying to find explanations for naturally occurring events, processes, or phenomena. In the end, they will create a theory in order to explain their observations and conclusions. The process under investigation doesn’t care that someone is giving it a name. There would still be gravity even if it wasn’t described by a theory. The planets would still move in elliptic tracks through space even if we didn’t know about it, and evolution would still be going on regardless of the history of its definition. Therefore, it is also obvious that a theory isn’t linked to the person who was the first to propose it. If Isaac Newton hadn’t come up with the theory of gravity, someone else would have. Does anyone seriously think that we would still believe that the earth is the center of the universe if Galileo Galilei hadn’t come up with his explanation for Nicolaus Copernicus’ assumptions?
Similarly, we would definitely have the theory of evolution today even if Darwin had never published a single writing. Actually, it was the manuscript of Alfred Russel Wallace, a fellow countryman of Darwin collecting specimen in the Malay Archipelago, that prompted Darwin to publish his book. Due to his work and to his own observations, Wallace had come up with a theory very similar to Darwin’s ideas. He was ready to publish it when he sought Darwin’s advice and sent him his manuscript in 1858. Realizing how close Wallace was to taking the credit for what he had worked on for decades, Darwin finally finished his work and published “On the origin of species” in 1859. Here, it is very obvious that the theory would be there independent of the first scientist proposing it. Yet, some people still speak of Darwinism when they mean the theory of evolution. That is an inadequate personification of science. Who would speak of Newtonism, Einsteinism, Keplerism, and the like? It would be inaccurate and we know it so why should different standards be applied to the theory of evolution? Scientific knowledge changes all the time and as with any other theory only those parts of Darwin’s ideas that were not refuted by later science are still accepted today.
The scientific method
In order to understand how science is supposed to work, one has to understand the scientific method. Every approach starts with observation and deduction. A scientist pays attention to a certain aspect that he wants to study, collects data, and starts to think about explanations by formulating a hypothesis which is an informed conjecture or statement of what might be true1/p.13. Next, the investigator has to test the hypothesis by setting up experiments. If the hypothesis is true, the outcome of the experiments can be predicted to a certain a degree. If the results are not coherent with the hypothesis, it must be dismissed or modified. In the process of experimentation, more and more data is collected at least until statistical errors can be excluded. If the results of various independent experiments support the hypothesis it will become a scientific theory. Here, a theory is a mature, coherent body of interconnected statements based on reasoning and evidence that explain a variety of observations1. In other words, a theory is an assumption that is supported by evidence beyond doubt. This is what is considered as a scientific “fact”, but as stated above it is not a fact in the common sense since it is still open to debate and improvement. In the end, one has to decide what they prefer: facts which usually come in the shape of dogmas and which are supposed to be believed without much questioning or theories that are always open for improvement, depending on the development of knowledge.
In that sense, I am glad that evolution is “only” a theory. Believing the same things that human beings believed thousands of years ago just because scripture tells us to do so doesn’t seem right. Moreover, it is not coherent with our understanding of progress and development. However, if some people still choose to regard parts of science as fallacious and inacceptable, I would hope that they have the honesty to be consistent. A creationist does not only have to deny evolution, but many other scientific fields as well including the scientific method in general. Hypocrisy is everywhere with creationists. After all, technology, medication, vaccinations, the standard of living, and much more are the results of modern science. If people deny science they should be consistent in order to be credible and not make use of anything modern science has given mankind. It is unlikely that they will do this though. God might be all-powerful, but the antibiotics developed over decades of scientific-based work, besides others, on the theory of evolution (drug resistance) are still doing a better job in curing people, or aren’t they? Modern medicine has always done what it can in order to help mankind where the Christian doctrines have done nothing but to make people feel guilty for being flawed since birth. Which side seems to have nobler intentions?
Evolution – Facts, Myths, and Misunderstandings
Part 10: Evolution and new (Genetic) Information
Since the theory of evolution describes the origin of the diversity of life, it obviously has to deal with a crucial question: how can new genetic information evolve? A vertebrate is much more complex than a single-celled bacterium. Thus, the genomes of bacteria and humans, for example, are very different. What is the source of their difference? Several different aspects have to be considered regarding this topic: first, genetic information can be taken up by a living being throughout its lifetime (lateral or horizontal gene transfer). Second, existing genetic information can be used in different ways, broadening the variety of available information. Third, new genetic information can appear and fuel the process of evolution.
1. Acquiring new DNA
It is well known that bacteria exchange certain parts of their genetic information with each other. Plasmids, ring shaped extrachromosomal DNA molecules, can be copied and transferred to another prokaryote. This is one of the reasons why bacteria can adapt so well to certain environmental circumstances, such as drugs. Drug resistance is often achieved through genes which are located on plasmids. Thus, if two bacteria exchange genetic information with each other, one could acquire beneficial genetic information from the other. This process can increase the pace of evolutionary change and might have played a significant role in the increase of genetic information that subsequently led to the evolution of more complex living beings.
Another process that can increase the amount of genetic information is the intake of genetic information directly from the environment. It is possible that ancient marine habitats (such as around so called black smokers in the deep see) contained some organic molecules such as amino acids and nucleotides. If a cell was able to “ingest” such molecules, it might have increased the raw material for other evolutionary processes to work on. With Cyanobacterium synechocystis, a fresh water blue-green alga, a species is known that can take up DNA from its environment. By doing so, it could possibly add useful information to its own genetic material.
Lateral gene transfer can also be achieved via viruses. Viruses are genetic elements that cannot replicate themselves independently but rely on a host cell. Sometimes the genetic information of the virus is incorporated into the genome of the host. Upon activation, the viral parts are cut out and packed into new particles. It is possible that parts of the hosts DNA will be cut out and incorporated into the new virus as well. If the virus then infects another organism or even species, it can function as a vector shuttling DNA from one organism to another. For example, a certain gene has been found only in one group of closely related species of cats and in Old World monkeys1/p.39. It is most likely that that gene was introduced into one of those species through a virus.
Once new information has entered a cell, it has to face natural selection and other evolutionary processes. As will be mentioned in part 12, molecular evolution can be simulated in the laboratory. If a random mixture of molecules (such as RNAs) is exposed to a certain selective pressure (such as binding affinity) and if these molecules are replicated again and again (different generations), the composition of the molecules will change. In the end, only those molecules which are “fit” for the task will remain. This is a likely scenario for the beginning of life and diversity.
Such simple processes seem to be of no significance for the evolution of more complex living beings, but it is crucial to know that the amount of genetic information is not necessarily correlated to the complexity of a species. This observation is called the C-value paradox1/p.458. The genome of a human being is about 3 Gb (three billion base pairs) long, but the genome of salamanders (order Caudata) can be up to 50 Gb long and the genome of some amoeba can even exceed 600 Gb (Amoeba dubia). In addition, there is no clear cut correlation between genome size and the amount of genes. Amoebas still have fewer genes than humans even though their genome is much bigger. However, it is possible that the first eukaryotes had huge genomes and the genetic information in future species didn’t increase, but decreased. The raw material was possibly there in single celled organisms, offering plenty of opportunities for mutations, genetic drift, and natural selection to occur and act.
2. Alternative use of existing genetic information
Several processes are known that increase the number of possible outcomes regarding the same genetic information. Alternative splicing is one of them. If the language of the genes is translated into the language of proteins (a process that is actually called translation) in eukaryotes, temporary molecules that transport the information from the nucleus (place of DNA storage) to the ribosomes (place of protein syntheses) are synthesized. These molecules are called messenger RNA (mRNA). Since the genome contains many parts that do not encode proteins, so does the mRNA. These “redundant” parts, called introns, have to be removed. The remaining coding parts, called exons, are then connected. This process is known as splicing. If all introns would always be removed and if all exons would always remain, the picture would be simple. However, that is not the case. Alternative splicing is a widespread mechanism for generating protein diversity, expanding the versatility of genomic sequences. It means that some exons are included in the final mRNA while others aren’t. Since genes contain numerous exons and introns, many varieties are possible. The results are numerous distinct mRNAs leading to distinct proteins. Some studies suggest that more than 35% of all human genes might be subjected to alternative splicing.
Another process that adds to the variety provided by a certain genome is exon shuffling. Here, one gene might contain exons (which often encode protein domains) from two or more genes that were formerly unrelated. Such a chimeric gene can come into existence through transpositions. Transposable elements (TEs) in general might play an important role in the evolution of genetic diversity. Such elements can copy and transpose themselves to other regions of the genome. In that sense, they can be seen as selfish genetic elements. In most cases, TEs have either no effect (since they are inserted into introns) or they have deleterious effects (if they are introduced into an exon, disrupting the gene). However, transpositions can occasionally lead to adaptive evolution as seen in the origin of the vertebrate immune system1/p.460. Today, there is little doubt that antibody diversity is generated by gene rearrangements2/p.929.
Several more processes are known that can increase the genetic variety such as replication slippage, chromosome rearrangements (inversions, translocations, fissions and fusions, change in chromosome numbers), motif multiplication, exon loss, gene chimerism and processed pseudogenes, gene conversion, and others. However, even if genes are not altered at all, phenotypic effects can vary widely as mentioned in part 8. The regulation of gene expression is a crucial and very significant process that can lead to highly variable outcomes despite similar genomes. Thus, evolutionary change in theory doesn’t even require an alteration of the genetic information in order to proceed.
3. The origin of new genetic information
Obviously, the examples mentioned above rather describe how already existing genetic material can be used in order to influence genetic variety. The ultimate question of course is: how does new information originate. First, due to recent advances in biochemistry and molecular biology, we now know that many different molecules such as proteins are related to each other. Two molecules are said to be homologous if they have derived from a common ancestor. The similarities between related proteins are often so obvious that the sequence of a newly discovered protein can provide important information regarding its function based on available information from a known protein.
Various examples are well known and studied2: the pattern of base-pairing interactions in transfer RNAs (tRNAs) suggests that these molecules had a common ancestor. Angiogenin and ribonuclease are so similar in structure that it is clear that they are both members of the same protein family despite their different biological functions (stimulating blood vessel growth versus RNA degradation). RuBisCO, an enzyme necessary for carbon fixation, is found in bacteria, eukaryotes, and even archaea, suggesting that an early common ancestor of all three kingdoms of life already possessed this enzyme. Glycogen phosphorylase, an enzyme necessary for glycogen metabolism, can be found in animals, plants, molds, and bacteria. The catalytic parts of the enzyme are similar or even identical in all living beings, showing that the catalytic mechanism has been maintained throughout evolution. Homologs of the proteasome, a cellular structure necessary for protein degradation, can be found in all eukaryotes as well as in prokaryotes and some archaea. Ubiquitin, a small molecule necessary for intracellular messaging, shows a high level of sequence similarity between the human and the yeast version. The cytochrome P450 system is a ubiquitous superfamily of monooxygenases that is present in plants, animals, and prokaryotes. The differences between these closely related enzymes are often defined by a few critical residues or even a single amino acid. Some of the DNA polymerases, enzymes synthesizing DNA, are clearly homologous. Others are different but have developed a similar three-dimensional structure, offering an example for convergent evolution on the molecular level. Genes that are involved in eye development are similar in vertebrates and in invertebrates, as for example eyeless or twin of eyeless in invertebrates and their homologues (Pax6 genes) in vertebrates. In principle, the same structures that enable human beings to hear (mechanosensory channels) have been found in fruit flies as well. Many more examples could be mentioned but these should be enough to make the point.
What is the point? First, it is undeniable that living beings are related to each other as shown by similarities on the molecular level. No matter how far two organisms might be apart genealogically, they will always have some genes and protein homologs in common. These relationships led to the discovery of whole gene and protein families. In humans, for example, about 1000 ribosomal RNAs are known which are so similar that there is little doubt that they share a common molecular ancestor. Second, the most obvious source for the occurrence of new genes that share similarities with preexisting genes is duplication followed by specialization.
“Mistakes” happen all the time during mitosis and meiosis. Many mistakes, or mutations, will be disadvantageous and thus will be selected against. Most mutations, however, are neutral – if changes occur in non-coding regions, the phenotype won’t be affected. If such a change brings forth the duplication of a gene, the copy will not be subjected to selective pressures. After all, the original gene will do its task, relieving the duplicate from any functions. Without selection pressures, mutations can accumulate until the gene has changed so much that it encodes a protein with a slightly different function that can be used as a variation or that can even be suited for new tasks. Isozymes, variations of an enzyme that differ only in a few residues, are a good example for that mechanism. Lactate dehydrogenase (LDH), for example, shows different variations depending on the tissue it is situated in. The catalyzed biochemical reaction is the same, but regulatory properties of the isozymes differ. The advantage is that the necessary task – the interconversion of pyruvate and lactate – can be performed in the lining of the heart (high oxygen levels) as well as in skeletal muscles (low oxygen levels). As will be mentioned in part 15, mechanisms leading to subtle evolutionary differences are the same in principle as those leading to vast changes. Bigger differences just need more time. Thus, the isozyme example only visualizes a very low level of possible alterations. As with all other aspects of evolution, the same principles apply at the molecular level: mutation, variation, recombination, and subsequently change through selection. The angiogenin-ribonuclease example mentioned above visualizes the variety of functions performed by proteins that are clearly part of the same protein family.
Besides genes, duplication can occur on higher levels of the genetic information as well. Polyploidy is the alteration of the number of all chromosomes, leading to a multiplication of the genetic information. As with gene duplication, a copy usually faces a lower selection pressure and is therefore prone to changes, providing a lot of raw material for evolutionary mechanisms to act upon. Polyploidy is best known in plants, but some animal species have also been influenced by the multiplication of entire chromosome sets.
Again, it doesn’t matter how many examples are used supporting the theory of evolution, it is still unlikely that a convinced opponent will accept any of them as valid evidence. Regarding the increase of genetic information, multiple sources have been mentioned throughout this article. They present a glimpse of what is known about the topic. Simply claiming that science has provided no credible information regarding the origin of new genetic information is simply wrong. As with other aspects, probabilities are low and might seem too unlikely to appear by natural means. However, the current results of evolution are the outcome of a process that has lasted for about four billion years. In addition, if the number of genes is considered, human beings do not even stand out as might be expected by the complexity of the species. Daphnia pulex, a common water flea, possesses about 31,000 genes, while Homo sapiens possesses “only” about 23,000 genes. The bottom line is that the picture is not that simple and the complexity of a species is a very complicated topic on the one hand and maybe an arbitrary categorization on the other. As mentioned before, it is possible that the single celled organism that gave rise to all eukaryotes (or even to all living beings) already possessed thousands of genes which then could be altered and specified in the course of evolution. Theoretically, if the first gene appeared four billion years ago and humans today have about 23,000 genes, the average rate of the emergence for a single new gene would be one in approximately 174,000 years. The probability for the emergence of a single gene might be low, but if you have such a time span for the development of DNA, such events become much more likely.
For further reading on the origin of genetic variation, see source #1, chapter 8.
Evolution – Facts, Myths, and Misunderstandings
Part 9: Intermediate Forms and “Missing Links”
The topic of transitional forms is also an issue that is mentioned again and again when the theory of evolution is questioned. As with other aspects, the incomplete understanding of fossils and the links between species is mostly based on the fact that things one cannot see are hard to imagine. A basic error that is commonly made is to assume that transitional forms should either be alive or be found in the fossil record in order for the theory to be true. It will be explained later in this issue why that doesn’t have to be the case. Even though fossils will not be the main focus of this article, a few basic principles necessary for the proper understanding of the topic have to be mentioned.
Fossilization is an extremely rare event. This is one of the main reasons why the fossil record is sketchy at best. Only under certain circumstances will the carcass of a deceased animal be preserved over millions of years. Scavengers, decomposing microorganisms, and erosion are parts of the circle of life that do not leave any remains behind in the majority of cases. Furthermore, environmental conditions have to be optimal in order to enable fossilization. For example, if the soil is too acidic even the bones will dissolve. Fossilization – the transition from biosphere to lithosphere, from life to stone – can only occur if decomposition is inhibited. For that to happen, a carcass has to be covered by sediments, ash, mud, etc., shielding it from oxygen (in order to inhibit decomposing aerobic bacteria that depend on oxygen) and scavengers. However, even under the most ideal circumstances everything but the bones and the teeth, where the minerals are exchanged by minerals from the surroundings (a process called petrification), usually vanishes since organic matter degrades. This is why only the hardest remains are available for science. Thus, besides its skeleton it is not always possible to conclude in detail what the animal looked like. Nevertheless, rare processes combined with a lot of time lead to many results.
So where are all of the fossils? Even if fossilization has occurred, it is everything but easy to find the remains. Certainly, millions or even billions of fossils lie buried somewhere around the globe – but how should one know where to look? This, in fact, is the second main reason for the incompleteness of the fossil record: it is not easy to find fossils and acquiring necessary funds for the search projects can be a real pain. It is safe to say that the whole fossil record and the understanding of past living beings would be revolutionized in a very short amount of time if paleontologists had budgets comparable to those of military spending. However, even if funding increased significantly, paleontologists would still depend to a major part on the earth’s most basic forces – plate tectonics and erosion – revealing fossils from its stony crust. In addition, it is likely that numerous fossils have already been found but weren’t recognized and therefore buried under concrete or soil. The bottom line is: finding fossils is anything but easy.
Nevertheless, despite the false claims of creationist propagandists, the fossil record offers a vast amount of insight into gradual changes of species. It is no coincidence that the remains of our ancient relatives (such as the famous Lucy fossil) show characteristics of both non-human primates living in trees and bipedal hominids (such as Homo sapiens). If fossils from the last 7 MY are considered, a gradual change from the last common ancestor of humans and apes to our species is undeniable. For other animals, such as horses and pigs, the fossil record is even more complete and the evolutionary change more visible.
A question that is sometimes raised by creationists goes like this: if species are related, why can’t we find the intermediate forms today? Why have no fossils of transitional forms been found? Well, as stated above, plenty of fossils of intermediate forms have been found – there is not much doubt about it within the scientific community. However, the background of these questions is a more problematic one. What creationists mean with transitional forms is a duck with the head of a crocodile, if the relationship of reptiles and birds is considered. This is the fallacy. When they think of intermediate forms they picture animals living today. Thus, the transitional forms in their minds must have possessed modern properties already. In order to visualize the fallacy, please remember the example of common descent mentioned in part 4. It is possible that parts of a family diverge for example due to the bad relationship of two brothers. If they avoid contact with each other, both branches of the family will develop independently. One part of the family might stay caucasian, the other part might become black. Remember, it all started with two brothers who had the same father. After 20 generations or so, two members of either side of the family might meet again – one black, one white. If someone claimed that both share a common ancestor, the creationist question mentioned above would go like this: if they share a common ancestor, where is the intermediate form? Where is the person whose skin is white on some parts and black on others? This, of course, wouldn’t make any sense. Even though both share a common ancestor (the father/mother of the two brothers in the beginning), they are very different today since they have changed (evolved) independently. Both have some traits in common with each other as well as with their ancient ancestors. However, certain differences such as skin color have accumulated over time. As ridiculous as a question about a half-white, half-black person would sound, this is exactly what creationists demand when asking for proof of common descent.
Another misunderstanding that can be cleared up with this example is this: transitional forms are usually not alive today. If they were, they wouldn’t be transitional forms but distinct species. 500 years after the two brothers have lived, their sons, grandsons, etc. will also be dead. Nevertheless, they would still be a kind of intermediate form considering the white and black family members that have just met. Evolutionary changes are so subtle that the definition of intermediate forms is prone to misunderstandings. Every species alive is not an intermediate form. Regarding its past and future relatives, however, it is – but only after it has vanished. This makes a whole lot of sense: how can something be a transitional form if it isn’t even certain yet what it will transform into?
Finally, a last metaphor considering fossils: imagine you find a picture of your grandmother when she was a child. You might recognize her due to certain characteristics, but she will look very different today. Imagine that this picture is a fossil that has been found and your grandmother is a species alive today. You might find a whole wealth of pictures (fossils) of your grandmother (species) as she grew up (evolved), visualizing her gradual change (evolution). By looking at these pictures, could you tell when she stopped being a child (one species) and started being an adult (another species); when she started to look old and when she stopped being able to digest lactose? Since you have only snapshots of her life in front of you, it is impossible to do so and even if you witnessed her whole life you couldn’t answer these questions since the change was too gradual. The same is true for the evolution of species. The foundations of evolution, again, are slow and gradual change and a whole lot of time. Species change all the time and the definition of the transformation of one into another is completely arbitrary. Asking for clear-cut intermediates misses the point. This is the reason why the distinctions between ancient species will actually get fuzzier the more fossils are found. It might sound like a paradox, but if you had a picture of your grandmother being seven years old and one where she was thirty, it would be easy to conclude that her transition from child to adult took place between these two snapshots. What if, however, you found pictures of her when she was ten, eleven, twelve, thirteen, fourteen years and so on? The task would become much more difficult and the difference would be much smaller. The same is true for fossils.
Nevertheless, it is completely understandable that people have a hard time imagining that the whole diversity of life is supposed to have originated from simple unicellular organisms. The evolution of cats and dogs from a common ancestor is a minor change in comparison to the origin of multicellular life. And yet, there is even a eukaryotic life form known that varies between a unicellular and a multicellular stage based on its life cycle. Starting as spores, the single celled amoeba Dictyostelium discoideum undergoes vegetative growth. As a reaction to starvation, however, many amoebae come together in order to form a multicellular slug. Some might not consider this agglomeration as a metazoan (multicellular organism), but a characteristic critical for its definition is met: a division of functions between the cells. In the end, the slug turns into a fruiting body which releases mature spores from its top, initiating the next life cycle. Thus, the transformation of unicellular into multicelluar organisms is everything but impossible and can even be studied in a Petri dish.
The living missing links
Still, shouldn’t there be something that at least looks like intermediate forms that close the gap between living species? Well, there is. The problem is that people don’t know what to look for. If, e.g., one wonders how fish turned into terrestrial animals such as lizards, what could an intermediate form look like? Certainly not like a fish with legs and claws. An intermediate form would combine both, certain fish traits and certain reptile traits. It might still be living in water but would also have legs – even if it only walked under water. If it is capable of leaving the water, it needs to be able to either breathe air (via simple lungs or the skin) or to keep its gills wet. It needs some kind of a neck in order to move its head three-dimensionally since its body can’t move three-dimensionally anymore outside the water. When reproducing, it probably would be better to let the eggs hatch in water in order to avoid the risk of drying out. Well, are there such animals alive today? Of course there are. Several amphibians would be appropriate for this example. Lungfish (subclass Dipnoi) are even considered as actual successors of missing links regarding the transition of fish to terrestrial animals. According to Brian Speer of UCMP Berkeley, “Their ‘lung’ is a modified swim bladder, which in most fish is used for buoyancy in swimming, but in the lungfish it also absorbs oxygen and removes wastes. Modern lungfish in Africa and South America are able to survive when their pools dry up by burrowing into the mud and sealing themselves into a mucous-lined burrow. During this time, they breathe air through their swim bladder instead of through their gills, and reduce their metabolic rate dramatically. These fish even drown if they are kept underwater and not allowed to breathe air! […] Lungfish are believed to be the closest living relatives of the tetrapods, and share a number of important characteristics with them. Among these characters are tooth enamel, separation of pulmonary blood flow from body blood flow, arrangement of the skull bones, and the presence of four similarly sized limbs with the same position and structure as the four tetrapod legs. However, there is still debate about the relationships among the Sarcopterygii.” (Source : http://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.html)
Regarding the gap between marine and terrestrial animals, my personal favorite example is the mudskipper (family Gobiidae). Even though they must stay moist at all times, they leave the water quite a lot and use their pectoral fins for walking on land. Seeing them act on land and in the water, it is not hard to imagine how such creatures could have been the first to leave the fluid medium hundreds of millions of years ago. Mud skippers show clear amphibious adaptations, enabling them to be quite active when the tide is low in contrast to other animals who they share their habitat with.
Another example is the transition of the forelimbs of birds from wings to fin-like structures. The wings of a turkey would be utterly useless if used under water, but many common ducks can dive fine for short amounts of time while using their wings to steer. The wings of alcid birds are used for flying under water as well as in air1/p.261. Finally, the wings of penguins have been modified into flippers and cannot support flight in air anymore. The diving abilities of turkeys and penguins have nothing in common, but several species can be found that exhibit diving abilities intermediate to either bird. If such examples of intermediate structures existing today cannot convince a doubting mind that transitions actually occurred, nothing can.
However, the study of “living missing links” does not have to be limited to whole organisms. Under the assumption that all living beings are related, several genes should cause the same phenotypic effect if transferred from one living being to another. Many genes are actually functionally and structurally conserved across taxa meaning that they haven’t changed a lot since the ancient split of the two lineages. If, for example, Pax6 genes of either mice or squids are expressed in Drosophila, they induce ectopic eye development. Pax6 is also responsible for eye development in vertebrates. Certain evidence suggests that at least two genes regulated by Pax6 have conserved functions in Drosophila and mammalian eye development1/p.483. This kind of relationship makes a whole lot of sense if vertebrates and invertebrates share a common ancestor. On the other hand, how would such a correlation make sense if all living beings where created individually?
The strengths of science
The topic of transitional forms is one that is often utilized by creationist attempts to discredit the theory of evolution. Even though hundreds of fossils document the gradual change of an ape into Homo sapiens (as will be discussed in more detail in part 16), many people resist to accept that humans have evolved in a way similar to every other living being. In addition, the whole concept of transitional forms is often poorly understood, causing a fallacious imagination regarding what these forms should look like. Nevertheless, the beauty of science lies in the fact that certain convictions are not held because of only one source of evidence. Instead, a whole multitude of areas is considered and a theory is only appreciated and accepted if the results of different approaches do not fundamentally contradict each other. Even if the fossil record didn’t contain any information useful for the theory of evolution, many other areas would: genetics, the geographical distribution of species, phylogenetics, comparative physiology and behavior, and others. The results of all of these disciplines complement each other, strengthening the theory of evolution with every new discovery rather than weakening it. Besides, even regarding fossils the scientific principle of falsifiability can be applied. After all, this is how science works: a theory is only accepted if it can’t be proven wrong, so scientists think of ways to test certain ideas. What could prove the theory of evolution wrong regarding the fossil record? Well, if the remains of a mammal were found in rock layers older than 500 MY, evolution would be in trouble since it predicts that mammals appeared much later than that. If the fossils of ancient humans and dinosaurs were found next to each other, Darwin might have been wrong. If excavations revealed that the rock layers got younger rather than older when digging deeper, creationists might have a point.
To date, not a single credible case calling the theory of evolution into question has been reported. It is worth considering that proving a scientific theory of such dimensions wrong could be the fast track to the Noble Prize. Rest assured that this alone is a great motivation for (scientific) critiques. On the other hand, what could be discovered that would make creationists accept that they were wrong? Here, it is important not to fall back on polemic phantasms such as: if I witness a cat giving birth to a dog I admit that I was wrong. Every single person can grab a shovel and look for the fossils mentioned above that would prove the theory of evolution wrong. Creationism also has to offer an equally testable way of being able to be proven wrong since falsifiability is the foundation of any scientific theory. If creationism cannot meet that standard, it will remain as invalid as it is at the moment. Without the applicability of the scientific method, creationism is nothing but assumptions and claims without evidence. It should be obvious that it belongs into the fantasy of private adorers instead of wasting the time and efforts of the scientific community.
Evolution – Facts, Myths, and Misunderstandings
Part 8: Additional Factors that Influence the Pace of Evolutionary Change
First of all, a few terms regarding the topic have to be considered carefully in order to avoid confusion. By definition (see part 1), evolution only occurs if allele frequencies within a population change. Thus, the definition applies to the genotypic and not to the phenotypic level – for good reasons. Take butterflies as an example. Every butterfly has been a caterpillar at some point in its past. People hundreds of years ago might not have known the connection and assumed that caterpillars and butterflies were completely different animals. If one didn’t know better, what reason would there have been to assume that both were in fact the same respective species? Comparably, every newborn looks much different than the grown organism. However, aging/growing up is not evolution. A zygote contains the same genetic information as the 80 year old human being it turns into. If the definition of evolution was based on phenotypic characteristics, the metamorphosis that turns a caterpillar into a butterfly would be an evolutionary event. As we know, it is not since evolution does not influence single organisms but populations over generations. As absurd as it may sound, a caterpillar and the butterfly that it turns into are genetically identical. Metaphorically, two genetically identical zygotes exposed to different environments could lead to a snake on the one side and to a bird on the other. In recent years, scientists have learned that many differences between species might be due to mechanisms influencing gene expression (how intensely a gene is read and turned into a protein) rather than differences in coding regions. How is that possible? The answer will be given later in this section. For now, it is important to understand that under certain conditions the appearance of a species can change considerably without a change in its genetic information. This, in turn, can fuel evolutionary change since such alterations will probably influence the allele frequencies within a population.
Nevertheless, there are events that influence the pace of evolution on the genetic level. One of these is pleiotropic effects. In a research project that lasted for 40 years and that was performed in Novosibirsk (Siberia), scientists investigated the effects of domestication on formerly wild animals, using the silver fox Vulpes vulpes (see Lyudmila N. Trut: Early Canid Domestication: The Farm-Fox Experiment). The group decided to select individuals generation after generation based on only a single trait: tamability. Every time, only those foxes that where the tamest of their generation were chosen for the next reproductive cycle. The results were clear: after four decades of intense artificial selection, the foxes were as tame as puppies even though they were as hostile to and as dismissive of human beings as any other wild carnivore before the experiment had started. This result didn’t come as much of a surprise since the scientists had already assumed that tamability was one of the first traits selected for in any animal that was domesticated by humans.
However, the experiment revealed even more interesting results. Even though the foxes were only selected based on tamability, other characteristics had changed as well. The domesticated foxes showed a delayed production of corticosteroids, a certain type of hormone, which altered their fear response. Furthermore, the fur color, clutch size, limb length, the form of ears and the tail, and other traits changed as well. There are several ways to explain why all of these changes occurred. It is known that certain genes which are physically close to each other on the DNA strand are linked during the rearrangements of chromatides during meiosis – a process called linkage. If one gene is selected for whatever reason, the other one will be selected as well. In addition, the notion that one gene contains the information for only one protein (or phenotypic trait) has been proven wrong. Scientists speak of pleiotropy when a single gene influences multiple phenotypic traits. Regarding the foxes, the gene responsible for tameness might also influence the other traits that have changed. The same can happen without human influence.
Examples of pleiotropic effects are even known for humans: “The gene that causes achondroplasia – the fibroplast growth factor receptor-3 gene – has the paradoxical effect of shortening limb length while leading to larger than average head size (megalencephaly).” 3/p.92 If a certain trait offers advantages to the respective organism, it will be selected by natural selection. If the gene that is responsible for that trait is linked to other genes or if it influences other characteristics, more changes within the population will occur even though natural selection is only directed toward that one trait that is most important for survival and reproduction.
A third way in which a single gene can lead to multiple phenotypic results is achieved through alternative splicing and exon shuffling. Here, it would take too long to explain the biochemical foundations. Therefore, I will keep the explanation very short but mention it for those who are familiar with the topic. It is well known that post-translational processes can alter mRNA in a multitude of ways. All mRNAs found in animals contain multiple introns and exons. It has been discovered that some mRNAs can be spliced in different ways, leading to different patterns of exons (alternative splicing). Depending on the number and orientation of the exons, the mRNA can contain information for different proteins. Since every mRNA is the copy of a gene, alternative splicing is another way in which a single gene can influence more than one phenotypic trait. Exon shuffling will be considered in more detail in part 10.
Horizontal gene transfer
Another way in which the genome of an organism can be altered is horizontal gene transfer. Where the transfer of genes from one generation to the next (from parent to offspring) is called vertical gene transfer, horizontal gene transfer describes the exchange of genetic information between two living organisms that are not related. It is best known from bacteria where certain genetic elements (plasmids) are commonly exchanged between two cells. This is one of the reasons why drug resistance can spread so rapidly as mentioned in part 7. If one bacterium gained the necessary genetic setup to deal with the drug, it could exchange such information with other bacteria. There is even an example of an organism, Cyanobacterium synechocystis (a fresh water blue-green algae), which is known to take up DNA from its environment. Even though much more rare, examples of horizontal gene transfer are also known for animals and plants. Some viruses incorporate their own genetic information into the genome of the cell they live in (host) before they amplify themselves and destroy their hosts. It can happen that parts of the DNA of the host are incorporated into the new particles along with the virus genes. If the virus then infects the cells of another species, the pieces of DNA from the first host can be transferred and incorporated into the genome of the second host. In the most extreme case, genetic information that actually alters phenotypic traits would be carried by a virus in this way from one organism to another, influencing the acceptor and its species.
Here, recombinational speciation (or hybrid speciation) shall only be mentioned for the sake of completeness. It describes the possibility of hybridizations that give rise to distinct species with the same ploidy as their parents1/p.398.
But how does it work that a caterpillar transforms into a butterfly? Why do some cells in our body turn into nerves, tissues, bones, and all the other parts of an animal if they are all identical regarding their DNA? The answers lie in the wide field of epigenetics. Epigenetics is a scientific area that deals with (heritable) changes in gene expression levels which are not manifested in the genome. Metaphorically speaking, the DNA is a home depot store with the potential to create a vast amount of different constructions. The factors which influence how often the different parts are used are then responsible for the actual outcome. It has been known for quite some time now that regulatory parts of the DNA outside the coding regions (the regions that carry the information for a protein) influence how intensely blueprints of a gene (mRNA) are created. The mRNAs are translated into a different language – the language of proteins. The more copies of a certain mRNA are produced, the more proteins are synthesized. Alterations in regulatory regions – reversible or irreversible – can therefore change the “activity” of a gene. Finally, the activity of a gene determines if a certain trait will emerge to a high or low degree – or not at all.
However, the irreversible change of a regulatory region is not an epigenetic effect if it is caused by changes in the DNA itself. True epigenetic effects are those that are reversible, such as the addition of a chemical group (methylations, acetylations, phosphorylations, etc.) to DNA or to proteins (especially histones which are in contact with DNA) which in turn influence gene expression. These alterations can be triggered by external sources, such as chemicals. Epigenetic effects are important for the response of an organism to changing environments. Since epigenetic factors could be transferred to the next generation via the female egg, these alterations could also be of significance for evolutionary change especially since they would speed the rise of phenotypic variation up considerably. After all, the DNA doesn’t even have to change for a caterpillar to turn into a butterfly. There, hormones and other effectors determine the change in gene expression during metamorphosis. Epigenetic effects are the reason why it is very unlikely – if not impossible – that a clone will become a perfect copy of the living being that it shares its DNA with.
For the sake of completeness, eukaryotic microRNAs have to be mentioned as well when gene expression is considered. MicroRNAs are very short fragments that can block the translation (use) of mRNAs by binding them. Even though the gene encoding the protein is not altered, the protein won’t be synthesized since the mRNA that carries the necessary information is blocked. In this way, genes can be silenced. Even though microRNAs are encoded in some part of the DNA, it is thinkable that new short RNA fragments enter an organism e.g. through a virus, causing an alteration of gene expression levels which in turn would influence the phenotype of the respective organism. In this way, the pace of evolution could also be altered by providing a greater level of variety.
Differences in gene expression could also lead to heterochronic or allometric changes as a source of differences between species. What it means is that the timing of development and therefore the proportions of body parts and organs change. Throughout evolution, the development of brain areas responsible for mechanical sensitivity in the nose of the star-nosed mole (Condylura cristata) began to develop earlier and earlier during the growth of the fetus. As a result, the nose got bigger and more sensitive in relation to other organs, enabling the mole to develop an exquisite tactile organ. A change of genetic information was not necessary for the exaggerated development of this preexisting organ since the information was already there.
When Darwin wrote his thoughts about the theory of evolution down, many things (such as genetics) that are necessary for a broad understanding of the topic weren’t known at the time. It is therefore not surprising that he was wrong with some of his assumptions. Rather, it is surprising how many times later science has proved him right. One of the lessons that every scientist should learn first is that science is a process – and not a result. If the evidence supports another theory, the investigator has to be open enough to reconsider his stance on the topic. As with other scientific areas as well, knowledge and understanding improve and change all the time. It is a fact that the process of evolution is not yet understood in every single detail. Scientists don’t always know what to make of certain observations. However, the awareness of uncertainties is not a statement of weakness or failure. It is a statement of honesty and openness. We can’t know what future discoveries will reveal, nor do we know if our understanding of factors influencing the pace and direction of evolution has to be altered. What we do know is that the theory of evolution in general is backed up by such a wealth of scientific evidence that there is no reason to assume that it is a falsehood. Sometimes science is wrong – but it is corrected by better science. There is no other rational alternative.
Evolution – Facts, Myths, and Misunderstandings
Part 7: Coevolution
If two species interact with each other, the change (evolution) of one is likely to influence or trigger the change of the other. That, in a nutshell, is the principle of coevolution. Don’t forget that living beings are always influenced by biotic (biological or living) and abiotic (non-living, chemical and geological) factors. Thus, the evolution of a species does not only depend on the climate and the environment it lives in, but also on the interactions with other species. It is not possible to talk about the evolution of the speed of the cheetah without considering the desired prey that can only be caught if the predator is fast enough. Why else would such a costly and exhausting trait evolve?
In order to analyze this process, the relationship between pathogens (harmful living beings and viruses) and human beings can offer a good example. When European colonizers set foot on Central and South American soil in the beginning of the 16th century, more indigenous people were killed by imported diseases such as measles, smallpox, influenza, whooping cough, or sexually transmitted diseases than by swords and muskets. Comparably, uncountable numbers of Native Americans died in North America after they came into contact with European settlers. Their weakness regarding diseases that were common for the settlers was ruthlessly utilized for example by providing the Native Americans with blankets from patients with chickenpox. The same problem emerges even between species. Eco-Tourists who are eager to see gorillas or chimpanzees in their natural habitat have to stay a certain minimum distance away from these primates. If infected with even the most common human cold virus or bacteria, the life of the animals would be at stake. Although they are less lethal to mankind itself, viruses causing the flu are also a challenge for human beings year after year, requiring annual vaccinations. What is the cause of such different reactions to the same pathogen?
The reasons for varying immune systems
The indigenous people living on the American continents were separated from the European group of Homo sapiens for thousands of years. Thus, both groups evolved independently. The duration of the separation, however, was too short to lead to the development of different species or even races. Nevertheless, certain traits did change as seen in skin color or body proportions. One inherent thing of an animal that also evolves over time is its immune system. Obeying the same evolutionary principles as macrostructures, a lot of variety is found when the immune systems of different members of a species are compared. Actually, this seems to be an example where evolutionary change should be very easy to understand. If a population is confronted with a disease, some individuals will be resistant to it while others won’t be. Those who aren’t as affected by the disease aren’t intentionally prepared. Remember, the key to evolution is variety, not intention. With thousands of people in a population, chances are high that some of them will be able to deal with a disease that is harmful to others just because formerly neutral traits come into action. Those individuals who are most prone to the disease might suffer lethal damage, removing their genes from the reproductive landscape. Immune individuals, however, will have the best chances of survival and reproduction (natural selection). Thus, more people will be able to deal with this very disease in the following generations. What is true for one pathogen is true for others as well. Over time, this process will repeat itself and the according population will become less and less prone to certain diseases.
So, when the Europeans entered the Americas, they brought pathogens with them that they had adapted to. Their immune system had evolved in order to deal with these threats. The indigenous people, however, encountered many of the imported diseases for the first time. Their immune system was simply not ready for it and couldn’t handle the microbiological attack. The same is true today for primates. They are so close to us that we can transmit diseases – or vice versa. Since they never had to face certain pathogens that infect humans, these microbes might have devastating effects for our biological relatives. A very popular example of humans contracting a disease from animals is the Human Immunodeficiency Virus (HIV). It is know that chimpanzees are commonly infected with the Simian Immunodeficiency Virus (SIV) which might be the predecessor of HIV. SIV does not cause the same effects in apes as it does in humans. It is reasonable to assume that the difference can be explained with our evolutionary past. Being exposed to the virus for thousands of years, only chimpanzees that were immune to the disease survived and reproduced in the long run. When the virus entered the human species in the 20th century, however, most immune systems weren’t ready for it which is why AIDS, the disease HIV causes, has become one of the most devastating pandemics of our time. Nevertheless, cases are known of human beings that carry the virus without getting sick. This would offer the possibility of adapting the human species to this very virus. In the past, this is how it probably would have worked. Only those that carried a certain resistance gene survived and reproduced, leading to adapted offspring.
The evolution of pathogens
How is this a good example of coevolution when only one part of the interaction (human beings) has changed so far by adapting to the pathogen? Well, diseases are always most devastating when the host organism encounters them for the first time – as exemplified by the indigenous people. The same is true for other populations. In that example, the Europeans weren’t always in contact with the pathogens that they are now immune against. At some point in time, the pathogen evolved and changed in a way that it could infect the human species. The Black Death, the plague in Europe in the 14th century, claimed the lives of almost half of the entire population. Recent research suggests that a variation of the bacteria causing this devastating disease (Yersinia pestis) had changed rather recently before the 14th century, giving it its deadly potential. Contemporary examples are known as well. The viruses causing the Severe Acute Respiratory Syndrome (SARS) and Swine Flu changed very recently, enabling them to spread across more species, including humans. Today, of course, due to modern medicine natural selection won’t kick in immediately, eradicating individuals prone to the disease. However, the principle is the same and worked many times in the past: a pathogen changed in a way that it became (more) harmful to the human species. The interaction partner therefore was forced to react to this new selection pressure by adapting. The change of one influenced the change of the other.
The “arms race” between predator and prey, or host and pathogen, can also be seen in bacteria or other microorganisms in many ways. Penicillin, for example, is a natural antibiotic produced by the mold Penicillium chrysogenum. Being attacked by bacteria as well as any other eukaryote, evolution provided molds with the ability to produce antibiotics in order to defend themselves against the intruders. Some bacteria in turn increased their resistance against these antibiotics, fuelling the arms race. On the other hand, bacteria can fall victim to viruses (bacteriophages). In recent decades, the so called RNA interference has been discovered as an elaborate mechanism within bacteria to counteract and avoid viral infections. Viruses, again, would then be forced to evolve in a way that they could overcome such defense mechanisms. The problem of drug resistance in modern medicine is based on the same principles.
If a selection pressure is applied (drug or vaccination), bacteria and viruses will change (evolve) due to natural selection until they have reached a state of resistance. Actually, this is an example of evolution that can be observed in a lifetime. Why else would it be necessary to find new vaccinations against the flu every year? Why else is it so hard to find reliable vaccinations against certain viruses, such as HIV? Viruses change and evolve very rapidly. In addition, they are produced billionfold in a single infected organism. Many of these copies carry mutations which are disadvantageous for the virus in most cases. Considering the sheer numbers, however, beneficial mutations will arise and spread if it means that the virus will be adapted to the drug better. Eventually, all the descending copies will carry the same mutation, decreasing the effect of the drug. This process might take a few weeks, a few years, or even generations, but it is likely to happen. Fortunately, modern medicine has found lasting vaccinations for many diseases. Remember that, when looking at evolutionary change, the principles considered here apply to natural circumstances. In the example given above, just exchange “drug” with “antibodies” or “leucocytes” or other natural self-defense mechanism. The bottom line is: the evolution of immune systems and the evolution of pathogens is a perfect example of coevolution.
The role of population densities
The sedentary lifestyle that human beings adopted about 10,000 years ago has changed the prerequisites for pathogens significantly. Many diseases are transferred by direct contact between two living beings. The more humans share a habitat, the easier it will be for pathogens to survive. Regarding the example of the vulnerability of the indigenous people towards European diseases, why was the encounter fatal for only one side? True, many Europeans also died due to diseases that were more common in the New World than in Europe. But their numbers weren’t even close to the devastating effects that the imported diseases had on the natives. The reason could be that some diseases depend on populations of certain sizes. Since population densities were higher in Europe and contact between different regions was more common than in the Americas, pathogens were provided with a more fruitful breeding ground in Europe. If populations are rather isolated from each other, as might have been the case in the New World, pathogens will have a harder time establishing themselves. This could have been the reason for the unequal results of the encounters between Europeans and Native Americans.
Consider, for example, measles: a child’s immune systems takes about two weeks to develop effective antibodies to fight the disease. Afterwards, it will be immune to measles. In order to be maintained in the population, the virus has to find a new host every two weeks, or, in other words, twenty-six children per year have to be available to encounter measles for the first time in order for the virus to survive in this population. Any European town would have had enough inhabitants, especially when the high child mortality is taken into account. Also, travelers could have spread the diseases to different regions. Native Americans, on the other hand, who usually lived in small tribes or villages, did not offer such potential for certain diseases to be sustained.
In some cases, the connection of the development of two species can lead to sophisticated relationships with mutual benefits called mutualism. Some fish are sometimes seen with smaller fish attached to or working on them. In the worst case, those fish would be blood sucking parasites, harming the host for their own benefit. In the best case, however, these fish are cleaner fish (such as Labroides dimidiatus) that remove smaller parasites and dead skin. At some point in the past, the bigger fish stopped chasing the cleaner fish away which in turn specialized in their task. Again, what sounds like intention or purpose probably was a slow process of adaptation, taking thousands of years. Similar examples are known from land mammals and reptiles which are cleaned by birds. Such behavior is mutually beneficial because the smaller partner gets to eat and the bigger partner improves its hygiene and parasite resistance. Another common scheme is the offering of goods such as food for protection. Certain ants live in mutualistic relationships with aphids. The ants keep predators such as lady bugs away and are supplied in turn with a sweet secretion which the aphids emit from their abdomens.
Mutualism, however, is not limited to animals only. The relationships between plants and animals feeding on their fruit are also very important. Many plants can only reproduce efficiently when their pollen or their seeds are carried away from the parent plant in order to avoid incest and competition. Thus, pollinators, such as insects, birds, or bats, are attracted with a source of energy – most commonly nectar. That the animals carry the sticky pollen attached to their surfaces to the next plant after they have drunk the nectar is not their intention, but it does the job. After fertilization is complete, it would be best for many plants to spread the produced seeds as far as possible in order to avoid competition with the mother plant. Again, it is animals that often do the job. By providing nutritious fruit, monkeys, birds, insects, and others are lured in. They either ingest the seeds and excrete them later in a different location, throw or carry them away, or are otherwise helpful regarding dispersal. Again, this is a splendid example for a relationship with mutual benefits that has coevolved over Millions of years.
In some cases, the two interaction partners become so dependent on each other that the extinction of one leads to the extinction of the other. Balanites wilsoniana, for example, is an African tree that produces huge seeds. The dispersal and the germination of the plant is only efficient if the fruit and the seeds are eaten by elephants (Loxodonta africana). Due to a decline of elephant populations in its home range, the number of young B. wilsoniana is dwindling. Species that are heading for extinction because an essential interaction partner has vanished are called “the living dead” in biology. Another example is the so called Dodo Tree, Calvaria major. Some scientists think that the dramatic decline of this species on the only island where it is found, Mauritius, is linked to the extinction of the dodo (Raphus cucullatus). It is possible, as known from other interactions, that the seeds had to go through the digestive tract of the dodo in order to germinate. Examples where the animal is threatened with extinction by the decline of the plant it relies on are known from the panda (Ailuropoda melanoleuca) in China and the koala (Phascolarctos cinereus) in Australia. Orangutans (genus Pongo) in Southeast Asia also play a vital role in seed dispersal in their home forests. However, due to the rapid decline of its habitat, the only Asian non-human great ape is heading for extinction.
A common evolutionary trend in order to reduce competition is niche divergence where related species tend to differ in certain aspects of their ecological demands and preferences. Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) coexist in some regions in Africa. Both species feed on leaves and fruit when both are readily available. Their behavior, however, differs during ecological crunch times. If fruit are scarce, gorillas fall back on a leafy diet whereas chimpanzees travel further in order to still find fruit (or even meat). This difference between both ape species seems to be small, but it is significant in order to avoid competition over food sources. The Darwin Finches (part 4) are another example of niche divergence: even though all of these birds are the descendants of the same founding population, they differ today in habitat choice, food, activity patterns, and other traits. Even human ancestors can serve as an example for niche divergence (see part 16): some bipedal apes which coexisted around Lake Turkana (Kenya) around 2 MYA developed stronger jaws and bigger teeth where other species developed larger brains, probably as a result of environmental constraints regarding available food in both cases.
Many more examples and variations of coevolution could be mentioned regarding either cooperation or competition between species. However, the examples mentioned above should be sufficient in order to understand the principle of coevolution: the evolution of different species are not isolated cases. In the natural world of balance and interaction, the change of one species will inevitably influence the change of another that it is in contact with. Likewise, the change of an organism is always connected to environmental factors. Therefore, many traits of living beings today only make sense in the light of the interactions they had to deal with during their evolutionary past.
Evolution – Facts, Myths, and Misunderstandings
Part 6: Sexual Selection
It seems as if females have always played a very powerful role in the evolution of many animals. After all, being the gender that has to deal with the burden of reproduction almost by itself, females can afford to be choosy in their mate choices. The genes and traits of the selected males will then be passed on to the next generation, determining the course of evolution. However, males do not only have to face the critical evaluation process of their desired mating partners, but also the competition with other males pursuing the same goals. Females usually mate less than their opposite gender since they are occupied with being pregnant or raising the offspring. Males, on the other hand, can copulate with many mating partners in a very short amount of time. This difference in reproductive potential is called reproductive asymmetry. It is obvious that under these circumstances males will compete over a scarcity of available females and their reproductive success will be unequal. Therefore, sexual selection is defined as a reproductive advantage which certain individuals have over others of the same sex and species. In other words, it adapts a species in a way so that its members can obtain a mate. Where natural selection usually favors organisms that are adapted well to the current environmental circumstances, sexual selection favors those who are most appealing to the females and who are able to outcompete other members of the same gender. In the most extreme case, the relationship between sexual and natural selection can be an antagonistic one.
Consider, for example, the long-tailed widow bird (Euplectes progne) from the southern part of Africa. Not surprisingly, it has gotten its name because of its extremely long tail feathers which are much longer than the bird itself. Without sexual selection, exaggerated structures like these could be an unsolvable puzzle for evolutionary biologists. Such long feathers decrease flight maneuverability and – being a burden when fleeing or hiding – increase the risk of being caught by a predator. Without sexual selection, the size of the feathers would almost certainly decrease over a rather short amount of time. Now, how can it be proven that it was the females who played a dominant role in the evolution of such an expensive trait? The necessary work has already been done in 19821/p.254. Scientists caught male widow birds and altered the length of their tail feathers. For some, the feathers were elongated with artificial “add-ons”. For others, feathers were shortened. The result was clear: females chose males with elongated tail feathers significantly more often than those with shortened feathers. Other characteristics, such as the maintenance of their territory, were not inhibited in the considered males. Further experiments performed with other species have yielded similar results: the more exaggerated a certain trait is, the higher the fitness of the individual carrying that trait will be.
As a result, the higher the level of competition is between males over available females, the more elaborate structures will evolve in order to attract the opposite gender. This is the root of sexual dimorphism – the phenotypic differences between males and females of the same species. Remember the example of sea elephants mentioned in part 5? Competition between males over the harems is intense and as a result bulls can weigh up to three times as much as cows. Why? Because bigger males had a better chance in winning the competition and therefore spread more of their genes. The picture is almost the same for gorillas (genus Gorilla). Silverbacks, adult males that monopolize the females of their group sometimes, might compete fiercely when encountering each other. Here, males reach twice the weight of females. Size, of course, is only one example of sexual dimorphism. In sea elephants, only the bulls have a large proboscis and the canines of male gorillas are much bigger than those of their female counterparts – to name only two further examples. Today, a good amount of evidence supports the notion that more sexual selection leads to a greater sexual dimorphism. As a rule of thumb (but exceptions are known), it is somewhat accurate to assume that less sexual dimorphism coincides with lower intraspecific competition and reproductive success that is more equally spread.
Taken to the extreme, female preferences might guide a species towards extinction. If the feathers of the long-tailed widow bird increase in size even more, they might become such a burden that the survival of the males and therefore the survival of the whole species might be at stake. There are theories about certain deer species that might have gone extinct because of antlers that became too big for the males to move and behave properly. Once again, the relationship between natural and sexual selection can be antagonistic. More probable than sexual selection leading to extinction, however, is a state of equilibrium between both mechanisms. Even though females would prefer the widow bird with the longest tail feathers, the disadvantages that come with the size of the feathers might be so crucial for their carriers that they won’t be able to reach the reproductive state (natural selection). Thus, the females have to choose from those males that make it, preferring the longest tails that are left (sexual selection).
The significance of sexual selection
Nevertheless, even if natural selection counterbalances certain tendencies, the role of sexual selection in evolutionary change should not be underestimated. Some scientists even believe that it can lead to speciation. If the taste for males in females is hereditary, the corresponding offspring will share these preferences. Some might prefer blue feathers on the top of the head of their mates, others might prefer black feathers. Over time, birds with mixed colors will disappear since they will be less appealing for mates and therefore fail in spreading their genes. One population might split into two even though initially the only difference between those groups was the color of the feathers on the top of their heads. Now, if the split is complete, members of the two groups will not interbreed anymore because one half is only looking for blue headed birds as mates while the other one chooses only black headed individuals. This separation – or reproductive isolation – then enables an independent development. With time, more traits and characteristics will change in the course of evolution until finally – after thousands of years – the two groups won’t be able to interbreed anymore. One species has turned into two. As theoretical as this scenario might sound – evidence for it has been found.
The so called Laupala Crickets (genus Laupala) on Hawaii presents an excellent example for the first steps that lead to speciation due to sexual selection. Differences between certain varieties (forms, subgroups) of this species are only found in secondary sexual characteristics (characteristics that are not directly involved in reproduction) such as mating calls. Members of each variety prefer the mating calls of their own subgroup. Thus, the differences between these subgroups will increase over time. Today, members of different subgroups can still interbreed and produce viable offspring. However, bear in mind that evolutionary processes such as speciation take thousands of years. There is a good chance that further change between these varieties could be documented as a real time proof for speciation – the only problem is that studies over centuries would be necessary. What we see now is a snapshot of an evolutionary event, progressing too slowly for human beings to see it with their own eyes. Again, even among the most devoted critics of the theory of evolution there is little doubt that all dogs are derived from wolves. Who, then, has witnessed the transformation of a wolf into a pug dog? Who can testify that the change has actually occurred? Nobody can, because even when we fast forward evolution due to our human influence, processes such as speciation take too much time to be noticeable during a human lifetime. After all, a St. Bernard and a dachshund are not even distinct species yet and might still be able to reproduce. If 15,000 years of intense selection brought forth such obvious phenotypic differences without even completing the process of speciation, it is not hard to understand that these processes take much more time without human influence. Bear in mind that the continental plates that we stand on move in respect to one another. The process is so slow that a human lifetime will never be enough to see obvious results of the movement, but the motion is there – slowly and constantly.
Coming back to the example of blue and black headed birds, think about blue tits (Parus caeruleus) and great tits (Parus major). These two species are very similar and only distinguished by minor differences in their songs, size, and the color of the feathers on their backs and heads. Imprinting studies have shown that either tit will try to mate with the other species later in life if it was raised among them as an orphan. Even if the mate preference is due to imprinting and not hereditary, the mentioned example of how speciation might occur remains valid. Maybe it actually was a similar process as the one described above that induced the split of an ancient tit species into the two contemporary species (runaway theory of sexual selection). Imagine that for some reason humans would strictly mate only with other humans with the same hair color. Over time, a once united population would split, leading to an independent development and further differentiation of the subgroups. As aforementioned, it is everything but absurd to assume that our ancestors at some point in time split up into different species of bipedal hominids. As a matter of fact we know that this is what happened – we might not yet be sure how and why but our direct ancestors certainly weren’t the only ones walking through Africa on two legs (see part 16).
Sexual selection in human beings
It should be easier to grasp the concept of sexual selection than other biological principles. After all, a lot of it can be observed in human beings. Yes, sociologist will hate me for saying it but we are animals after all and sometimes our instincts take over. It seems to be much easier to make this comparison with men since their mate choices seem to depend more on phenotypic traits than those of women. Sometimes it is truly amazing and entertaining what some men will do to compete over girls. Sure, we can always blame it on the role society has pressured us into, but even in indigenous people young men have to endure challenges in order to define their rank among their peer group. The one that comes out on top will be the first one to choose a mate. Women, on the other hand, work hard to improve their appearance in order to attract the other gender. Even though many people reading this will be upset with the notion that human beings are primitive animals in some ways, one example really makes the point and I can’t imagine how someone would refute it: the instinct to reproduce is a strong one. After all, species without that instinct would go extinct quickly.
Human beings, like any other living being, reproduce because they want to spread their genes to the next generation. If that primitive reason didn’t play a role, why are women willing to go through so much pain during birth, risking their health or even life? Why the effort of carrying an ever-growing weight in their womb for nine months? If biological reasons or instincts are not so important, why not spare the pain and trouble and adopt a child? Human beings feel an urge to reproduce – but claim that they are not bound to primitive instincts. How does it match? A billion people are starving around the world today, but our species keeps breeding and breeding. How is that not primitive? Many (not all) people say that an adopted child will never be like your own, especially if you have a biological child as well. If grown up orphans are asked why they want to meet their biological parents, they usually say that they want to know where they come from. Biological ties are strong – and yet many people live in denial. A fact never considered is that giving birth to a child is always a selfish instinct. “I want a child!” If the child will have the chance to live a happy and fulfilled life as it deserves is only the second thing that is taken into account. In many societies, children are even considered as laborers for their own families. We do not even dare to forbid child molesters to father children. Reproducing is a human right – how can that not be driven by primitive instincts?
On a lighter note: did you ever wonder why sex is fun? Well, if it was very unpleasant, would you do it? Would anyone do it? Probably not. The result would be the extinction of our species. Thus, only those who enjoyed having sex in the past reproduced and spread the genes that encoded those sexual characteristics that made copulation fun. Even if we pride ourselves by saying that due to contraceptives we have sex for other reasons than reproduction, we miss an important point. The sexual desire or urge is in us because of our evolutionary past. The sexual drive is an indispensible necessity for the survival of any lineage that reproduces via sex. The ultimate cause is not altered only because we change the outcome. Infants put everything in their mouths that they can get. They won’t be able to suck milk out of their pacifier, and still they have this drive because sucking on mothers breasts has always been essential for survival. The urge to suck in babies stems from the necessity to be weaned as much as the urge to have sex in grownups stems from the necessity to reproduce. So yes, even in human beings the instinct to reproduce and the desire for sex cannot be separated. When in ecstasy, our hips thrust without even thinking about it. That is our instincts kicking in.
We should gladly accept that our ancestors have made the process of reproduction fun. No one would prefer to mate like bed bugs (family Cimicidae). Having no time for romance, males inseminate females by piercing their copulatory organ through the abdomen of their unfortunate partners, ejaculating in the body cavity. There is a lesson to be learned here: nature is full of surprises and exceptions and even traumatic insemination (or rape) can be a stable reproductive strategy. Since evolution does not pursue any goals or values, such examples do not trouble biological explanations a lot. On the other hand: why would an all-powerful creator design several animal species where the females are necessarily raped? One morbid designer that must be.
Evolution – Facts, Myths, and Misunderstandings
Part 5: Survival of the Fittest
The concept of fitness is also one that is sometimes misunderstood even among some scientists. The German translation of “Survival of the Fittest” means “Survival of the Strongest” (Überleben des Stärkeren), which is an inaccurate description. Biological fitness is not primarily defined through physical properties, but through reproductive success. It is defined as the amount of genes an individual contributes to the next generation. Thus, a lot of offspring means that the fitness of this organism is high. I have no children. Therefore, my fitness is pretty low. So far, my genes are only partially spread to the next generation through my brother’s son since we are related and share some genes (this is called inclusive fitness; it considers genes spread by both my relatives and myself). It is important to understand that by definition fitness does not include any properties such as the level of adaptation regarding the current environment or physical strength or appeal. However, if there weren’t any correlations between physical traits and fitness, how could evolution progress and conserve adaptations? There are correlations of course. An organism that is well adapted to its environment will have a higher chance of surviving and finding a mate. Similarly, an organism that can cope better with a changing environment will also be more likely to reproduce. If the individual is strong and healthy enough to outcompete others it will have better chances to succeed as well. The bottom line is this: there is an obvious correlation between physical traits of an organism and its reproductive success. However, I insist on keeping the definition of biological fitness linked to gene flow for the following reason: there is always room for chance and bad or good luck in evolution. Maybe the strongest and most fertile buck that the face of the earth has ever seen has already lived but it couldn’t influence the development of its species in a positive way because it was hunted down and killed by a pack of wolves before it had the chance to reproduce. If the pond runs dry, it doesn’t matter how well adapted the carp that lived there was to challenging environmental conditions. Being dependent on its habitat, his superior genes vanished with the last drop of water. It is possible that about a few hundred years ago the most intelligent human being to ever walk the planet already existed. When a strong winter depleted the food supply, however, he or she died together with the rest of his or her group. Regarding the concept of biological fitness, the element of chance must not be neglected. Furthermore, there is another powerful evolutionary strategy that undermines the notion of the strongest individual yielding the most offspring even more:
Alternative mating strategies
Examples are plentiful. Chimpanzees (Pan troglodytes), a highly social species, follow strict hierarchical structures. Theoretically, the alpha-male would have a monopoly on mating with the females of the group. However, genetic analysis revealed that sometimes less than 50 percent of the young were fathered by the alpha-male. How is that possible? First, females have an interest in mating with several males for the simple reason of decreasing the risk of infanticide. If the hierarchy structure changes or if the dominant male is aware that a child was not fathered by him, the young could be killed. This makes sense in an evolutionary perspective since the dominant male wants to spread his own genes and females are more likely to mate again when they do not have to take care of an infant. Comparably, if a male lion takes over a new pack, infanticide is common. So, mating with several males could be a strategy of deception. If the males don’t know if they have fathered the child, it would be better to assist in its protection rather than to kill it. After all, it might carry their genes. Furthermore, the bonds between some chimpanzees are stronger than those between others. Just as humans don’t get along with everyone, chimps have their best friends and opponents within their group. To some, the alpha-male might just not be appealing. Therefore, they would prefer to mate with other members of the group. Secret mating has been observed in the wild as well as in captivity. We have good reason to believe that they are aware of doing something “forbidden” – or why else would they be as sneaky as they are? While they are at it, they stay alert all the time in case the alpha-male spots them. When everything is over they depart quickly as if nothing has happened. Here, the alpha-male is strong enough to fight its way up to the top of the hierarchy. Exclusive reproductive success, however, is mere theory.
A similar case of secret mating is known from sea elephants (genus Mirounga). After fierce fights between males, the winner gains control over the entire harem of females and infants. However, sometimes the group might be so big that it is virtually impossible to watch over every single cow all the time. Again, genetic tests have revealed that not all of the offspring are fathered by the dominant male. Males without their own harem might wait at the periphery of the group for their chance to mate or they might try to mate when the females are in the water. This example and the chimpanzee one visualize how diversity is maintained even under conditions where it should decrease significantly due to an assumed reproductive monopoly. Nevertheless, those are not the best examples of alternative mating strategies since they are a case of behavior rather than predetermined physiological adaptations. Instead, they might just be an example of “making the best of a bad situation”. The inferior males are not able to compete with the dominant ones but find a way to achieve at least some reproductive success.
True examples of alternative mating strategies are known from orangutans (genus Pongo), marine isopods (Paracerceis sculpta), and crickets and toads (satellite males) – to name only a few. Adult orangutan males inhabit large territories where they try to monopolize the females that live there. Other grown up males that enter the territory are confronted with hostility. Even though it is not known in detail how they do it, it has been observed that some orangutan males reach the reproductive state while their physical properties remain at the level of an adolescent. This phenomenon (which is an example of neoteny) enables the subordinate males to mate with females in a territory that isn’t theirs3/p.189. They are partially protected by their adolescent appearance since dominant males tolerate non-adult males. In the marine isopod Paracerceis sculpta, three male phenotypes are known. One is big and dominant (alpha), one is medium and resembles females (beta), and one is very small (gamma). The alpha-form is the most common one but does not succeed in completely outcompeting the other two forms. The beta-form gets to mate with a few females since it resembles females itself and therefore is not chased away by alpha. The gamma-form is simply small enough to be sneaky and has some reproductive success as well. Again, one form is dominant and stronger than the others, but because of the mentioned reasons variability does not decrease as would be expected in theory. In fact, the various forms of isopod males serve as an example for frequency dependent selection: the reproductive success of a certain genotype depends on the genotype frequencies in the population. In other words, the more alpha-males are abundant in the isopod population, the lower their relative reproductive success will be. Hence, for the next generation the frequency of alpha will decrease while the frequency for beta or gamma (or both) will increase. If there are only very few gamma males, they will have a very high relative reproductive success since they will be hard to spot by the dominant males.
The last example refers to an alternative mating strategy that is known as satellite males which is observed in some crickets, toads, and other animals. In a nut shell, bigger and stronger males try to lure females in for mating by calling out loud for them. Smaller males that wouldn’t stand a chance in an open competition with the stronger ones wait at the periphery of the callers and try to “steal” the incoming females. How could such a strategy survive throughout evolution? The satellite males risk not finding a mate by not calling at all, but on the other hand they avoid being heard by a predator. In other words, the calling males will attract attention, but attention is not always a good thing especially if smaller males utilize their efforts. Since the decision of calling or not calling is predetermined by the genes, why aren’t the calling males going instinct then? Well, if there weren’t any calling males, the species might go extinct as a whole since encounters with females would become too scarce. The less calling males there are, the more females they will attract per capita. Thus, their reproductive success (or their fitness) will be very high and more male callers will be born. If there were many more calling males than satellite males, on the other hand, the latter would have a very high fitness since they wouldn’t have to compete with many other satellites and since many calling males would lure many females in as potential mates. This is another example of frequency dependent selection. The lower the frequency of a certain trait is, the higher its fitness might become.
Imagine a species where one part of the group feeds on fruit while the other part feeds on vegetables. If 90 percent of them feed on fruit, this part of the group will run out of food soon and eventually many of their members will starve. The vegetable eaters, on the other hand, have an abundance of food since only 10 percent of the population will eat it. Thus, these individuals have a much better chance of surviving and reproducing. Their offspring will prefer vegetables as well and the balance of preferences will shift due to differential reproductive success. These and many other examples make one strong point: there is much more to fitness than just strength or adaptedness. In the most extreme case, traits that make surviving harder will lead to an increased fitness due to sexual selection – which will be considered in part 6.
Evolution – Facts, Myths, and Misunderstandings
Part 4: Adaptation, Radiation, and Speciation
In biology, and maybe in other areas of science as well, categories cannot always be defined in an unequivocal manner. Sometimes the decision about where one description ends and another begins is a matter of interpretation. Changes and differences in nature are not separate events, but rather nuances of the same category. The fact that natural definitions are not always exclusive is an issue that will reappear throughout this work time and again. If one wants to understand science it is crucial to accept that the absence of an unequivocal categorization is not a weakness of scientific descriptions. Rather, one has to understand that concepts of perfection or unambiguousness are artificial human constructs that have no place in nature.
Take a population for example. How is such a group of individuals defined in biology? Most commonly, a population is defined as a group of interbreeding living beings (same species) that coexist in a certain area. If a carp population in a pond is considered, the matter is clear. But what about habitats that do not separate a population from another one as strictly as a pond does? What about deer populations in a forest? Should all deer in North America be considered as one population because theoretically they could all migrate and breed with each other? Or should they be defined in smaller groups, taking regional distinctions into account? As aforementioned, since differences are subtle and changes gradual in nature, boarders separating one category from another can be very blurry up to the point where they are merely a matter of interpretation.
The species concept is another example of the difficulties regarding unequivocal descriptions. So far no definition has been found that all scientists agree on and that would incorporate the peculiarities of all living beings. However, it is unlikely that such a consensus will ever be reached. If the diversity of life was an everlasting equilibrium with stable species the problem would be easy to resolve. Yet, one must not forget that living beings are constantly changing. If a species is in the process of splitting up into two daughter species, how can one define when the old species is gone and when the new ones are established? Similarly, try to consider a human being and define to the day when it stopped being a child and when it became an adolescent. It is virtually impossible and can only be achieved by arbitrary categorization. Nevertheless, every existing concept has to be defined in some way. Regarding species, the definition made up by Ernst Mayr is the one most commonly referred to: species are groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups1/p.355. It applies to the majority of cases, but bear in mind that in an imperfect nature exceptions are not uncommon.
The concept of speciation describes the process of how new species come into being. In principle, speciation is distinguished into two different forms: the two developing species coexist in one geographical area and are capable of encountering each other (sympatric speciation) or they are physically separated (allopatric speciation). The latter is more common, especially in its most extreme form called isolation. Examples for isolations can be found everywhere. An existing population might be fragmented by an emerging canyon, a river that has changed its course, or emerging mountain ranges. A group might just migrate, e.g. when food is too scarce to feed the whole population. One of the best known examples is, of course, Darwin’s Finches. Evidence has been gathered again and again that birds (or other flying animals) can be blown far into the sea by strong storms. Most of those unfortunate little creatures probably died struggling against the bad weather. However, it needed only a small founding population – or even only one pregnant female – to reach the Galapagos Islands once to start a new population (conveniently, this could be used as an example for the founder effect where the focus lies on the specific genetic makeup of the individuals that found a population; see genetic drift in part 2). Considering the distance between the mainland and the Galapagos Islands, this seems to be an unlikely event. Once again, if you combine low probabilities with a lot of time, chances increase significantly – and evolution has never been short on time.
The advantage for a living being that has just reached a new habitat might be a very low level of competition. Being the first birds on those islands, the finches could reproduce and prosper. Many ecological niches such as seed eaters, insectivores, or fruit eaters, were not taken yet. In addition, there was neither a lot of competition from other animals in the trees nor on the ground. When the founding population grew and spread across the islands, variation was an inevitable part of their development. Some finches might have preferred to stay on the ground while others chose to live in trees. Some birds were born with stronger beaks, enabling them to crack nuts or open seeds. Some were born with pointier and elongated beaks which increased the success of catching insects. They differed in color, size, and wing span. This did not happen within a few generations of course, but over hundreds of thousands of years. By filling different ecological spheres (niches) the finches were able to reduce the competition that arose from a growing founding population – a process known as niche divergence or competition avoidance. After all, if diets and habitats are different, there is not much to compete over. In the end, when Darwin arrived at the Galapagos Islands he found birds so diverse that he designated them as members of different families. To his surprise, when he came back to England he was told that all the birds he had collected were in fact members of the same family. Due to the isolated nature of their island habitats, these finches could change so much that they couldn’t even be recognized as closely related anymore – comparable to the change of dogs (except slower of course).
In order to understand the case of the finches, it might be helpful to try to find correlations to human beings. Isolation has lead to some variety in our own species as well. Consider the Pygmy peoples for example which lived isolated in rainforests until European explorers established contact with them. The most obvious difference is that – in the most extreme cases – they reach only half of the height of an average European or American. The Moken people of South-East Asia are also known as “sea gypsies”. Due to their predominant way of life on the sea, their ability to see under water is much better than those of any other human group. Indigenous Inuit, living under very cold conditions, have short limbs which reduce heat loss. Moreover, the circulation in their hands and feet works much better than for any other human group, enabling them to touch ice cold items without damaging their fingers. More examples could be listed, but these three should be enough to make the point for now.
Last but not least, the field of evolutionary geography deals with the observation that the history of a species is always the history of spatial distribution. Closely related species live in relative vicinity to each other instead of at opposing ends of the world. It is no coincidence that relatives of the finches mentioned above can be found on the west coast of mainland South America. If creationism were true, why aren’t closely related species spread randomly all over the world?
Adaptation and radiation
The Darwin Finches can be used as an example for at least two biological concepts: Speciation after isolation (as mentioned above) and adaptive radiation. An adaptation is a characteristic that enhances the reproductive success of organisms that has it (and is therefore linked to increased survival rates), relative to alternative character states1/p.247. This means an adaptation is a trait that increases fitness. Regarding radiation, imagine the shoot of a bush starting to grow. If it is free to grow in any direction it will branch again and again until it is a fully grown bush. Now imagine the first finches on the Galapagos Islands. As mentioned earlier, the level of competition was low. Under these circumstances, an organism that contains traits that enable it to outcompete others can evolve over time into several species with distinct properties, filling the niches that were abandoned beforehand. If these speciation processes are visualized as a diagram, the form of a bush appears starting from a single root and spreading into multiple branches. That is radiation. It is called adaptive radiation because the environmental constraints determine the change, or adaptation, of the species. In other words: adaptive radiation describes a group of closely related organisms that have evolved different features enabling them to exploit different ecological niches. For that purpose, anatomical as well as behavioral traits that increase the reproductive process of the individual can be adaptive. Keep in mind that adaptations as a link between an organism and its environment are the direct consequence of natural selection. With recent discoveries we begin to understand more and more that the development of bipedalism (walking on two legs) was probably one of these new traits that opened up several new niches and enabled radiation. The origin of the Homo sapiens was not a straight path, but rather the story of one bipedal animal surviving while dozens of others went extinct. Before the Neanderthals vanished a few thousand years ago, our ancestors weren’t the only species walking upright. This, however, will be the topic of part 16.
To end this part, a few words about the last common ancestor of the genus Homo and the genus Pan shall be mentioned because this topic is the root of a major misunderstanding. I have two brothers. If you knew my bigger brother and you knew that we were related, would you conclude that I have descended from him? It wouldn’t make sense, would it? We are both descendants of my father (or my mother, respectively). After we were born we both developed independently but equally. No one developed more than the other. Now, as obvious as this example is, some people do not see the apparent link to evolutionary processes. Saying that we have evolved from chimpanzees is downright wrong. As I have just pointed out, it would be like saying that I descended from my older brother. Human beings and chimpanzees share a common ancestor as much as my brother and I share one (our father). Since our paths started diverging, human beings have changed – but so have chimpanzees. So it is simply wrong to look at such an ape and say: “Hm, that’s what we looked like in the past…” It might be true that our last common ancestor looked more like a chimpanzee than a human being, but the point is that this ancestor is not alive anymore. Comparably, imagine that I have a very bad relationship with my brother and I will never see him again. Our descendants may meet some time in the future by chance. My side of the family might have become black, where my brothers side of the family stayed Caucasian. After all, both sides are the descendants of my father – no matter how much they have changed since the split. It is that simple.
To some, the following line will sound convincing: “If we have evolved from monkeys, why are there still monkeys left? Shouldn’t they all have evolved into humans by now?” No, they shouldn’t have. Think about the previously mentioned example of dogs. If they evolved from wolves (as we are sure that they did), why are there still wolves left? Evolution has no purpose or goal, it doesn’t follow a path, and it is not straight forward! Some species have survived almost unaltered for millions of years. That does not, however, exclude the possibility that a subgroup of that species did indeed change and became another species. Species don’t behave as a whole, but as a collection of individuals. The change of one organism doesn’t tell you anything about the change of another. Furthermore, one more thing has to be taken into consideration: just because one cannot personally imagine something doesn’t mean that it isn’t possible. Remember the enzyme example from part 3. Another example is this: at the equator, the earth rotates at the speed of 1670 kilometers an hour (or about 1000 mph). That is faster than common airplanes! By just being present on this very planet we move forward by 464 meters every single second. Why aren’t we centrifuged into space? It is hard to imagine that the ground we stand on moves with the speed of a fighter jet, but the limitations of our imagination have no value for the truth of such phenomena whatsoever. Bear in mind that subjective constraints, regarding both knowledge and imagination, have no influence on the accuracy of naturalistic descriptions. Or is there anyone out there questioning the theory of gravitation because the mentioned numbers just don’t seem to be right?
Evolution – Facts, Myths, and Misunderstandings
Part 3: Evolution and Time
Bear in mind that evolution is a process that does not change the individual, but that alters a population or a species over generations. In order to understand the theory properly, one has to get familiar with the time periods that have passed between the emergence of the first cell and today. Those who would like to find a weakness in the theory of evolution argue that it cannot explain the origin of life conclusively. As a matter of fact, it doesn’t have to – and it never tried. Evolution explains the diversity of life through gradual changes of existing living beings. Not even once has it tried to explain how it all started. Comparably, would any person of sane mind question the Theory of Gravity because it doesn’t explain how gravity came into being? In the realm of science it is important to stay accurate and to understand the limitations and intentions of certain approaches. Another example is the Big Bang Theory which doesn’t have to answer the question of what existed before the origin of the universe. It is out of its reach and has nothing to do with it. Questioning a theory on something that it doesn’t even intend to answer is inaccurate and doesn’t make any sense. It only shows that the person asking the question doesn’t understand what the theory is all about.
The inherent limits of our imagination
So, instead of asking how, we can only ask when it started. Scientists today believe that the universe as we know it came into existence about 14 billion years ago. Immense heat and energy were released after the Big Bang and the universe has been expanding ever since. Over time, temperatures dropped and enabled the first planets to appear. The earth formed about 4.5 billion years ago and continued cooling. Shortly after – speaking in astrological terms – the first life forms came into being about 3.5 billion years ago (prokaryotic like single cells). This immense time frame is the key to grasp the potential of evolution. It is understandable that human beings have a hard time imagining that all living things, including complex and sophisticated species like our own, are supposed to have evolved from a single bacteria-like cell. The problem is that we are too naïve to accept our inherent limitations. 100 years seems to be a very long time for us since it exceeds the life expectancy of almost any human being. The world was completely different in many ways 2,000 years ago when one of the most influential pieces of literature (the Bible) was written. Our own species might not be older than 100,000 years – a wink in geological terms but we find it difficult to imagine the time that has passed since. On the other hand, we can simply not imagine or understand how a single enzyme can perform its task 1,000,000 times – in only one second. Our imaginary fields, the dimensions of time and space that we can grasp, have their limits. In evolutionary terms it all makes sense. It was never necessary to understand what millions of years meant since human beings were living one day at a time for the longest part of their history. Neither was it beneficial to understand the concept of 1/1,000,000th of a second since it had no value whatsoever. Things we can imagine and understand have their limits. We have to be aware of these limits in order to understand certain aspects properly. Minor changes, as insignificant as they might be, can sum up to massive proportions given enough time.
About 1.5 billion years ago the first eukaryotic cells originated. The main difference between bacteria (and archea) and eukaryotes is that the latter contains a nucleus in which the DNA is stored. They are crucially important because they were the basis for multicellular organisms. Today, all animals, plants, and molds are made up of eukaryotic cells. Very important for the development of terrestrial life was the increase in oxygen concentrations in the atmosphere that started about 2 billion years ago due to marine cyanobacteria and certain algae. About 1 billion years ago the first multicellular organisms developed leading to the first animals about 600 million years ago. Further details on evolutionary timelines can be found in any good book about the topic. For now, it is only important to know that evolution had almost 3.5 billion years to turn a preliminary cell into a human being and all the other living beings that live today.
Dogs: evolution fast forwarded
If people doubt that such major changes are out of the reach of evolution, they should consider the development of domesticated dogs. All races of dogs are descendants of wolves (Canis lupus) which is underlined by their taxonomic name: Canis lupus familiaris. The domestication of that carnivore started about 15,000 years ago. Today, so many different variations of dogs are known that no one would define a pug dog and an Irish Wolfhound as the same species if they saw them for the first time. This massive change was achieved in only 15,000 years of evolution. Sure, the selection pressure was artificially high due to the human influence. However, the dog example visualizes the potential for change that lies within living beings and it shows how fast evolution can proceed under certain circumstances. After all, humans guided the change, but they didn’t change the genetic makeup of the dogs. They could only use what was already there. If the selection pressure is lower, evolutionary change will take more time. As stated above, time was always abundant. If the differences between human beings and their closest relatives, chimpanzees (Pan troglodytes) and bonobos (Pan bonobo) are considered, it doesn’t seem so unlikely anymore that we shared a common ancestor about seven million years ago. After all, these differences evolved over a time period that was 470 times longer than the split of wolves into pug dogs and Irish Wolfhounds.
Some people might still say that they can understand that an animal changes into another one of its kind (even though they are careful enough not to define kind), however, the transformation of a dog into a cat is unthinkable. In the worst and most ignorant case they would say things such as they have never seen a cat give birth to a dog. Yes, but I have also never seen a Pomeranian squeeze out a St. Bernard – so what is your point? We still agree that both dog species are related, or don’t we? Sometimes the complete lack of scientific knowledge of opponents of the theory of evolution is staggering. The issue of microevolution (change within a species) and macroevolution (change on a higher taxonomic level) will be dealt with in part 15. For now, it is enough to point out that believing in microevolution but not in macroevolution is like saying: “I can walk to my neighbor’s house, but it is impossible to walk to the neighboring town.”
Evolution within a human lifetime
Several examples of evolutionary change within a few decades could be named to underline the power of this process that is guided by natural selection. For the sake of briefness, one example should be enough here to make the case. From 1953 on, warfarin was used as a poison against brown rats (Rattus norvegicus) in Britain. Only five years later, resistance was reported in certain rat populations which had a strong survival advantage if exposed to warfarin in comparison to other wild-type populations, even though the mutation that enabled their advantage caused a decrease of vitamin K regeneration efficiency1/p.277. Hence, affected rats might have a problem of taking up enough vitamin K with their food, but as long as survival rates are higher among those with the mutation than those without, natural selection is going to push the evolutionary change towards warfarin resistant rats. As will be explained later in part 14, the handicap of being less efficient in regenerating vitamin K due to a mutation in a gene encoding a crucial enzyme does not pose a problem for the theory of evolution. Evolution is not about perfection – it is about being above a certain threshold that enables the members of a species to spread their genes successfully.
Several similar examples are known regarding resistance of insects to insecticides, of bacteria and viruses to drugs (part 7), of rodents or salamanders to snake poison, and others.
Evolution – Facts, Myths, and Misunderstandings
Part 2: Evolutionary Mechanisms
The question remains how evolution proceeds or in other words: Which mechanisms gear the change? Darwin wasn’t the first one who thought and wrote about the development of species. Many thinkers before him, including his own grandfather Erasmus Darwin, speculated that species aren’t constant but instead change over time. So why did Charles Darwin become so famous? What was his contribution to the already existing idea of evolution? Before his time, no evolutionary mechanism was known. Some scientists and philosophers argued that the characteristics of a species change over time, but they couldn’t explain how and why they did. Darwin’s work was groundbreaking because he was the first who discovered a coherent theory for the main mechanism by which evolution acts: a mechanism which he called natural selection. Now many processes and changes in nature could be explained in a conclusive way. The second major point of his work was his theory that all living beings are the descendents of the same ancient living being and that all species are subject to gradual changes. Darwin was the first one who created the concept of a tree of life that, first, had only one stem or origin, and second, didn’t have the need for a creator. It was this insight that troubled the religious elites of the time the most as well as Darwin himself as he was raised in a conservative Christian environment.
In addition to natural selection, other mechanisms/processes driving evolutionary change are known today: Mutations, genetic Drift, and gene flow. Where natural selection is a deterministic, non-random process, mutation, genetic drift, and gene flow are elements of chance.
1.) Natural selection
Someone who breeds animals or plants is eager to perfect certain traits. In order to achieve their goals, they would choose those individuals which have the desired phenotype for their breeding project. In this case, only those plants or animals that are suited for the task will be allowed to reproduce. All the others will not be selected and won’t have a chance to spread their genes. This would be a case of artificial (or anthropogenic) selection. It doesn’t happen that way in nature, of course, but the principle of selection is the same. Some animals will be weak and sickly, unable to find a mate, or otherwise disadvantaged. In an unending struggle for food, space, and mating partners, they will lose and eventually die without reproducing. Natural selection means that under the given circumstances those who are adapted the least will be the first to face death or at least a life without reproductive success. Thus, only those who present the needed requirements will be able to live on and spread their genes. “Bad” genes won’t usually make it to the next generation. Genes that provide necessary physical abilities, on the other hand, will. Which genes prove to be beneficial and which don’t depends on the environment and on the level of competition. A vivid example of how natural selection works is the lack of poor vision in indigenous people. Hereditary shortsightedness is common in industrialized countries, but not among native African tribes. Why is that?
Since the dawn of man, African people had to share their environment (the savanna) with a number of other predators, such as lions or leopards. An individual that was born with shortsightedness would have a hard time surviving until maturity. If one sees deadly predators too late, the predators will have the upper hand. Thus, shortsightedness can be a lethal disadvantage in the bush. Only those with sharp vision will prove themselves as successful hunters and protectors, earning the chance to reproduce and spread their genes. Here, natural selection favors individuals with excellent vision. Under different circumstances (for example in the absence of predators), however, the results could vary. For the same reasons, many hereditary diseases are less frequent in less developed areas than in industrialized nations. The more a human being relies on his physic (and indigenous people rely on it a lot), the more devastating a bodily handicap would be. Weak and sick individuals therefore died more frequently in the past without having the chance to pass on their “bad” genes. Similarly, a cheetah that gets short of breath easily won’t make it for long in the wilderness. Only those who are fast and enduring enough to catch prey will be able to survive and contribute their genes to the next generation. Since fast cheetahs were more successful hunters in the past than slow ones, natural selection favored the first. This is how cheetahs became one of the fastest land animals on the planet over time. To summarize, natural selection is the change of traits or characteristics within a population due to differential reproductive success.
What is crucial to understand about natural selection or evolution as a whole is that neither one is directed towards the good of a species. Natural selection is not guided by any goals or purposes and affects only individuals. The resulting change over generations does not necessarily have to benefit the species. Natural selection does not hold any long term implications, but only leads to immediate advantages instead. There are no forces that try to keep a species alive and neither are individuals concerned with the well being of their own kind. If they were, extinctions would be rare – but they are not. After all, about 99 percent of all species that have lived so far have gone extinct.
Mutations are random changes in the DNA (the hereditary/genetic information) of a living being that occur during the process of replication (growth/division of cells). It is the ultimate source of variability and new genetic information within populations. The occurrence of mutations is increased by certain factors that damage DNA, such as radiation, chemicals, or even viruses. However, even without these factors mutations happen frequently in all living beings. When cells reproduce, the DNA they contain has to be amplified as well. During that copying mechanism, mistakes (mutations) that change the DNA occur time and again. Even human beings carry thousands of mutations in their genome and accumulate even more as they age. Mutations are, however, very rare and the reason why they occur so frequently within our genetic information is the incredible length of DNA where a single copy consists of three billion pairs of basic units called nucleotides (however, the length of DNA is usually measured in base pairs).
A mutation could change a single nucleotide, a group of nucleotides, or even entire chromosomes. Most changes in our genes would be detrimental and disadvantageous. Only a very small fraction of mutations that affect genes have positive effects. Why is it then that these vast numbers of mutations don’t hurt us even more? The reason is that even though mutations occur frequently, genes are not affected in most cases. Those parts of our DNA that determine the layout and function of our cells – the genes – constitute only a very small fraction of the genome. Scientific studies estimate that only five or even as little as one percent of our DNA is made up of genes. Thus, the majority of the mutations affect areas that do not directly determine the phenotype. Such changes are called silent or neutral mutations, since their effects cannot be perceived in the phenotype. Over time, silent mutations can happen at a particular DNA region again and again until a formerly non-coding region (genes are coding regions) turns into a new gene and therefore into a new or altered phenotypic trait. So, non-coding DNA regions (except regions that influence gene expression) can serve as a kind of trial and error playground until enough changes have accumulated to influence the phenotype. Existing genes will not change as frequently since alterations would directly affect the phenotype with negative consequences in most cases as stated earlier. Natural selection would kick in and “remove” detrimental mutations – in other words, the animal carrying this detrimental mutation would suffer from a lower reproductive success. There is some pressure on existing genes to stay as they are in order to benefit the individual. This pressure is called selection pressure. The higher the selection pressure, the more important it is that no negative changes occur. Non-coding regions are less stable because the selection pressure is much lower for them. After all, if these regions change, no mechanism will remove the changes in most cases.
3.) Genetic drift
Genetic drift can have a massive influence on the evolution of a species even though it might not be as comprehensible as the other two processes. It describes the change of allele frequencies that occur for random reasons and is therefore an example of non-adaptive evolution. Besides adaptations that provide a living being with the necessary tools to outcompete others, chance is always a factor. The strongest, healthiest, and most appealing stallion won’t spread its genes when it is killed by a pack of wolves early in life. A lion with good stamina, sharp teeth, and sharp claws unseen before can’t spread his supreme genes if he can’t find a female to mate with. The most agile, strong, and fertile carp will not make a difference for his species when his pond runs dry. Parasites or diseases could kill the majority of a population and only a few members could survive due to luck or immunity. The bottom line is that those who get to reproduce determine the course of the evolution of their species. Sometimes certain genes play a very minor role and have no influence on reproduction whatsoever. In that case, the changes of these gene frequencies are due to random sampling. They are passed on as “silent passengers”. Such random sampling can lead to a complete phasing out of one allele to the benefit of another solely based on chance. Flipping a coin is an example of random sampling. Even though very unlikely, it is possible to get “heads” ten times in a row for no reason but chance. Genetic drift works in similar ways. Eventually, such traits that were of minor importance might become crucial when environmental circumstances change. Comparably, if parts of a population are isolated or if a population is diminished by environmental factors, the genetic makeup of this smaller group will comprise the raw material for the evolution of these individuals (bottleneck effect). If environmental conditions change, this group might then be better adapted to the new circumstances – even though the differences between these groups and the former ones are due to random reasons. In this context, it is important to note that the effects of genetic drift are bigger in smaller populations. That is, since there is no great number of individuals with the established genetic makeup that could outbreed individuals carrying unusual variations, small groups are more prone to evolutionary changes, diversification, extinction, and speciation.
4.) Gene flow
In a nutshell, gene flow describes the exchange of genetic information between populations. Depending on the environment they live in, any group of living beings will be unique in certain ways, adapted to the local circumstances. As always, there will be genetic variability amongst the members of a group. If migratory events lead to an exchange of individuals between different groups, the genetic diversity of the receiving population will increase due to the imported genes of the new members. The increased variability will then contribute to the potential of the group to adapt to its environment in times of change. Without gene flow (isolation), the genetic diversity within a population could decrease crucially.
What is important to understand is that living beings today are not the way they are because of accidents. Even though mutations, genetic drift, and to a certain degree gene flow present randomness, natural selection doesn’t. It is the interplay between variation in a population and natural selection that molds the change of a species. In that way, natural selection is everything but blind. It guides the change in order to enable the species to adapt to changing environments. The outcome, of course, is unclear. Evolution is not predictable since environmental change is not foreseeable either. Evolution has no purpose, no goal, and no end. Talking about the climax of evolution or about living beings that are more evolved than others doesn’t make sense since it implies intention. There is no purpose or intention in science in general – no matter if that thought is uncomfortable for some people or not. Evolution doesn’t care that we are here; neither does nature. Without human beings, a different species would take over our niche and life would continue as it always has. The only difference would be that the world would lack a cocky animal that thinks it is more important than other living beings.
Evolution – Facts, Myths, and Misunderstandings
Part 1: What is Evolution?
The term “evolution“ is carelessly used today to mean change through time. Such oversimplifications are inaccurate and in some cases even nonsense. When the amount of water in a leaking glass changes, we observe change over time but certainly not evolution. Evolution today is applied to culture, astrology, music, sports, and various other fields. Here, the term “evolution” shall only be used in its original biological sense. The theory of evolution is an attempt to explain the diversity of life – and nothing else!
So what is evolution? Evolution is defined as a change in allele frequencies within a population over time. What does it mean? Every living being is born with the inherent information necessary for life. This “blueprint” determines the structure of every cell and tissue, certain behaviors and characteristics, and the ability to reproduce. The hereditary “currency”, which is passed on from parent to child, is a long biomolecule called DNA (deoxyribonucleic acid). The DNA partly consists of genes, which carry the information for a certain peptide or protein each. Some genes determine the color of our eyes, hair, or skin, some determine our height, some determine our ability to build up muscles or fat, etc. The entity of all genes of an individual constitutes the genotype – it cannot be seen or otherwise perceived from the outside. Everything about a living being that can be perceived by another living being (such as looks, smells, sounds) is called the phenotype. Since the genes carry the necessary information, the phenotype is directly linked to and determined by the genotype. In other words, what you see is a projection of your genes.
So far so good – but what are alleles? Most living beings consist of millions or even billions of cells with varying functions and structures. Regarding sexual reproduction, however, all of these cells contain the same DNA since they are all equally the descendants of a single fertilized egg (zygote). Within the cell, the DNA is not stored in one piece, but instead partitioned into several fragments, called chromosomes. Human cells contain 46 chromosomes each – twice as much as they need. Human beings, and many other living beings, have two complete sets of DNA within a single cell – they are diploid. Within the zygote (and therefore in every descendant cell), 23 chromosomes are derived from the egg (mother) and the other 23 chromosomes are derived from the fertilizing spermatozoid (father). Since both sets of chromosomes constitute the entire DNA of each parent, every gene (such as the gene for eye color) will be present twice in every human being. Finally, alleles are different variations of a gene that occurs more than once. Imagine a construction area where all blueprints are present twice. One can build only one house, so in the end there will be only one visible outcome. However, the architect can choose between two different variations of the blueprint. In that metaphor, there would be a gene for building a house. The two variations of the plan would be the alleles. If someone inherits a gene for blue eye color from his father and one for brown eye color from his mother, he has two different alleles (or variations) of the same gene – the gene determining eye color.
Regarding that example, this person would carry the combination blue/brown. Someone else might carry the information green/blue, a third person brown/grey. If all members of a population are considered, the alleles can be counted and their frequencies could be determined. These frequencies (the relative numbers of alleles) change from one generation to the next (over time) since not all members of a species have the same reproductive success. A particular person with more children will pass more of his genes for eye color on to the next generation than someone with fewer children. What is true for genes regarding eye color is true for any other gene as well. Hence, the allele frequencies within a population change over time. That is evolution. It happens everywhere, all the time – no matter if you see it or not.
The beauty of the theory of evolution is not only that it is backed up by a vast amount of scientific evidence, but that it’s also logic in theory. If certain basic circumstances are considered, one comes to understand that evolution is inevitable. Imagine a herd of horses and ask yourself four basic questions:
1.) Are all of these horses identical in genotype and phenotype?
2.) If there are differences between the individuals, are those differences hereditary?
3.) Are all horses going to have the same reproductive success?
4.) Is there going to be competition between the individuals over food, mating partners, territory, hierarchies, or other sources?
Except for identical twins, it is virtually impossible for two living beings to have an identical genetic makeup. Why that is will be explained in part 12. Thus, variation is all over. The horses will differ in height, stamina, color, length, thickness of hair, wideness of hooves, chewing power, or even the resistance to a certain toxic plant. These variations might seem small or even insignificant, however, differences are abundant and they distinguish one horse from another.
As stated earlier, our phenotype is determined by our genotype. Bear in mind that our phenotype is also determined by other factors which will be dealt with in part 8. For now, however, it is sufficient to consider the simple genotype-phenotype relation. Since a lot of variability is found in the herd of horses and since these differences are mainly due to variations in the genetic makeup, traits and characteristics will be passed on from one generation to the next. A very tall horse is likely to have tall offspring. The progeny of a horse with brown hair will probably have the same coloring. A powerful stallion is meant to father a strong son. It is no coincidence that offspring resemble their parents to a certain degree. Heredity is the chain that connects two generations.
3.) Differential reproductive success
In any population, independent of the species, not all individuals will have the same reproductive success. In the most extreme case, an Alpha-Male will monopolize most of the females for exclusive mating. Regarding the herd of horses, some individuals will be stronger than others, more enduring, or simply more appealing to the opposite gender. While some stallions will mate with multiple mares, some won’t have the chance to reproduce at all. Therefore, those who father more offspring will multiply their own genes while the genes of those who didn’t father any foals will go extinct. A simple example to visualize this process is the development of names in human beings. Some names will spread within a population since the bearers of the name reproduce successfully. Other names, however, will go extinct when they can’t be passed on to the next generation. In evolutionary terms, some names prove to be more successful than others. The genetic contribution of an individual to the next generation is called its fitness. Therefore, more offspring equals a greater fitness since more genes are passed on.
Competition for food, mating partners, territory, places in the hierarchy, etc. is inevitable. If there were no restrictions or limits, the whole world would be overpopulated with horses (or any other living being for that matter). But there are restrictions. Herds cannot simply grow without end. Eventually, food and space would become scarce, tensions would rise, and some individuals wouldn’t find enough to eat and starve or die of thirst. In any species, not every newborn will reach adulthood. There can even be competition within a mammalian womb (where one fetus can absorb another) or within a nest (birds), to name two further examples. Besides the competition within one species, there is always the threat of predators, parasites, diseases, or environmental factors. When growing up, adolescents might struggle with their position in the hierarchy. Later, they will have to compete over mating partners and territories. To cut a long story short: Competition is everywhere. It is obvious that some individuals will have an advantage over others. Regarding the horses, under most circumstances a strong foal will have the best chances of outcompeting its contemporaries. Developing into a strong stallion, it will then have the best chances of finding a female to mate with. Under different circumstances, horses with thicker hair might survive an unexceptionally hard winter when horses with thinner hair won’t. If food is scarce, smaller horses might have a better chance of surviving due to their lower energy demand. In all cases, those individuals who manage to reproduce will spread their genes and traits to the next generation. Since every individual is unique, the combination of some traits will prove more beneficial under given circumstances than others. If these traits remain superior or beneficial for some time, future members of the herd will inherit those traits and the whole appearance of the population might change.
If all of these questions and conclusion are considered, it is obvious that evolution is inevitable. Environmental conditions change constantly, therefore species have to change in order to cope with these new conditions – they have to adapt. They don’t do it consciously, of course. They change because they have no choice. A basic principle of evolution that must be understood is this: evolution never changes a living being. It can only be observed between different generations. Allele frequencies change everywhere and all the time – but not within an animal. Evolution is an ongoing process that will never end.
Evolution – Facts, Myths, and Misunderstandings
When Charles R. Darwin published his book “On the Origin of Species“ in 1859, he did not only revolutionize science but also the image of man. Even though it wasn’t his primary intention, Darwin questioned the authority of the almighty creator regarding the creation of natural diversity and the human species itself. The church reacted by doing what it had always done with progressive minds, condemned Darwin’s “godless propaganda”, and urged him to abrogate his theory without even considering the possibility that his teachings might be correct. Unfortunately, not even the majority of his colleagues at the time recognized the accuracy and ingenuity of Darwin’s observations and conclusions, causing him a lot of distress and hostility in public discourses. However, by the time he died in 1882, the importance of his works was widely accepted and acknowledged when he was honored with being buried at Westminster Abbey – next to the greatest minds of his country.
The acceptance of the theory he put forth, the theory of evolution, didn’t reach the levels it should have amongst the public. An increasing amount of scientific data backed up most of his predictions providing ever growing support for his ideas. In addition, new discoveries in the field of genetics resembled Darwin’s observations and interpretations, even though the mechanisms of heredity weren’t yet discovered at his time. However, the human mind seems to work in mysterious ways and instead of replacing the idea that God is solely responsible for the origin and diversity of all living things with Darwin’s theory of evolution, creationism never left the pseudo-scientific arena and has had a strong comeback in recent decades.
Creationism is not commonly believed amongst biologist, especially amongst those who deal with evolutionary topics. However, the majority of the population in many countries is poorly educated regarding such scientific areas. In order to teach creationism and deny evolution, one has to misrepresent science – consciously or unconsciously –, distort facts, or simply lie. Similar to a conspiracy theory, due to their lack of expertise many people might then fall for such propaganda if it is presented in a persuasive way. That’s the true strength of creationists: since they don’t have a lot of facts or evidence to rely on, they focus on their presentation. After all, as long as people don’t know more about certain topics than the speaker does, they will believe almost everything you say – as long as you know how to be convincing.
The misunderstanding and the misrepresentation of the theory of evolution in public are certainly among the main problems responsible for its incomplete acceptance. Hence, the purpose of this series of articles is to clear up misunderstandings, explain basic principles of evolution in a comprehensible way, and to increase the understanding and acceptance of science. For that purpose, several basic questions or doubts regarding evolution shall be mentioned and answered. It goes without saying that more could be said about any topic but the goal of this series is to combine briefness with accuracy and comprehensibility. The articles partially build upon each other, meaning they should be read chronologically. From now on, one part of this series will be uploaded every week.
Despite the fact that I have a degree in biology, scientific work is not my current profession. I am well aware that some of my arguments might be flawed or incomplete. If you have suggestions for corrections, please feel free to comment. Moreover, I have to make clear that my intention is not and has never been to argue against faith or to convince people to become atheists. My intention solely is to keep religion out of science and other areas where it could do harm. Independent of my own convictions, I would prefer if believers found their own personal way to whatever they consider as their supernatural power. I am not making a case against spirituality; I am making a case against dogmas, lies, and deceit.