Jerry Coyne’s Why Evolution is True
I understand it contradicts the account in the Bible and other holy texts, if one takes a literalist interpretive stance, but given that most texts have more significant internal conflicts, I did not see why this particular theory would cause people to have such visceral emotional responses. I understand, intellectually, that evolution is not the first scientific advance to be met with tremendous hostility; there was also significant opposition to the notion of a heliocentric universe and to the idea that the earth was not flat. However, because people understand that other scientific ideas that were intertwined with biblical teachings have been proven incorrect before without damaging religious belief, I imagine that I assumed that people would be more open-minded about “modern” scientific theories. On the contrary, because of the strong scientific support for the idea of evolution, the choice not to believe evolution seems to be an aggressively anti-scientific response, so much so that it seems to bleed over into other areas of scientific belief in those who oppose evolution.
I believe that Coyne captures the essence of why people have such a strong opposition to evolution when he states that “Evolution gives us the true account of our origins, replacing the myths that satisfied us for thousands of years. Some find this deeply frightening, other ineffably thrilling” (Coyne, p.xv). Furthermore, evolution connects people to animals in a way that many find threatening, especially given the systemic use, mistreatment, and abuse of animals by people. Given that it was less than 200 years ago that many people in the United States adamantly opposed the idea that humans of different races were members of the same species, it should come as no surprise that the idea that humans and other apes evolved from common ancestors was such a controversial one. In many ways, I believe that this is tangled up in religious perspectives, which is a theme that Coyne explores throughout the book. The more fundamentalist the country, like Turkey or the United States, the more likely they are to be resistant to the idea of evolution. Moreover, in the United States, even people who believe in evolution may advocate for the teaching of creationism / intelligent design in science classrooms as an alternative theory, despite the lack of any evidence to support creationism and the overwhelming evidentiary support for evolution.
Coyne gives a comprehensive definition of evolution that explains the theory of evolution and the role that natural selection plays in the evolutionary process. He states that:
Life on earth evolved gradually beginning with one primitive species — perhaps a self-replicating molecule- that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) evolutionary changes is natural selection (Coyne, p.3).
Of course, this is a modern definition of evolution, informed by scientific discoveries that have helped shape the understanding of the age of the earth in comparison to the ages of plant and animal species. When Darwin first proposed the theory of evolution, it did not begin with an understanding of the earth’s age and was not backed by as much evidence from the fossil record. Instead, he began with the premise that plant and animal species evolve. This evolution simply refers to a series of genetic changes over time. Moreover, these changes are generally going to improve function for a specific environment for the plant or animal.
One argument that people make against evolution is the notion that some plant and animal species have remained unchanged over significant periods of time. However, this argument ignores the theory underlying natural selection. Natural selection suggests that those members of a species that are best-suited for survival in a particular environment will be more likely to reproduce in that environment. As a result, those traits will, gradually, become more prominent in the population, which will change the species’ overall genetic makeup over the course of several generations. However, certain events can hasten natural selection, so that some species may evolve much more quickly than other species. Furthermore, if an environment remains relatively stable and a species is already highly functioning within that environment, one would expect to see few, if any, changes to that species over time.
Probably the biggest barrier to proving evolution is that it is, generally, not something that people can personally observe. Antibiotic resistance among bacteria is one example of evolution that can occur within the lifetime of an observer, but it is not something that the lay person will observe in their lifetimes. That is why the fossil record is an important element of the evolutionary argument. Fossils provide evidence of animal species that have previously lived in certain locations. However, the fossils themselves are relatively useless without accompanying ways to date those fossils. By being able to attach dates to certain fossils, scientists have been able to put together a fossil record. This fossil record shows evolution over time.
The fossil record, while providing some of the best supporting evidence for evolution, is also used by some anti-evolutionists as a way to attack evolutionary science. There are gaps in the fossil record. When one considers that a complete fossil record would require excavation of, literally, every location on this planet, which is literally impossible with modern technology, the expectation is that the fossil record would be incomplete. Furthermore, it is critical to understand that not all remains will become fossilized:
The formation of fossils is straightforward, but requires a very specific set of circumstances. First, the remains of an animal or plant must find their way into water, sink to the bottom, and get quickly covered by sediment so that they don’t decay or get scattered by scavengers…Once buried safely in the sediments, the hard parts of fossils become infiltrated or replaced by dissolved minerals. What remains is a cast of a living creatures that becomes compressed into rock by the pressure of the sediments piling on top (Coyne, pp.21-22).
What this process necessarily means is that fossils will develop from only a very small percentage of all plants and animals of each species, and that some species may not exist at all in the fossil record. Therefore, gaps in the fossil record are to be expected and do not detract from evolution.
In addition to the fossil record, living plant and animal species provide evidence of evolution. Many species have vestigial organs, which serve no function, but still exist. The fact that they have these features is suggestive of evolution. In addition, as animals grown from the embryonic stage, they go through many stages that seem very distinct from the final human form. Finally, some parts on animals seem ill-adapted for their environments. Coyne describes the wings in the flightless ostrich as vestigial organs that the animals cannot use for their original intended purpose, flight, but the animals have evolved uses for them (p.57). Despite the fact that these organs may have uses, they are still vestigial organs, because they are not used for their evolutionary purpose. In humans, the most obvious example of a vestigial organ is the appendix, whose removal not only does not create problems for a person, but actually seems to reduce the incidence of disease. However, the appendix serves a purpose in animals that subsist mainly on plants, which is how the vestigial organ provides evidence of evolution.
The genetic record also provides evidence for evolution, specifically through atavisms and dead genes. The fact that some species have atavisms, which are sporadic appearances of organs that would have been useful in an ancestor species, such as the appearance of a tail in a human, provide proof of a genetic history outside of what is known as a modern human characteristic. Humans have 2,000 dead or pseudo genes, which serve no function in humans (Coyne, p.67). However, how these pseudo genes prove evolution is that they have uses in related species, but no use in other species.
One of the more interesting aspects of evolution is that evolution is tied to geography. In fact, it was through a geographical journey that Darwin was first able to note evidence of isolation-driven evolution by observing how different animal species evolved in relative isolation on islands. However, more puzzling than the presence of very different animal species living on isolated islands is the idea that similar species have developed in different areas. This can be explained by the idea of convergent evolution. Convergent evolution suggests that species living in similar habitats will evolve in similar ways because they will experience the same environmental pressures (Coyne, p.94). What this means is that species that are not related may actually look alike because they evolve the same adaptations.
Coyne describes the process of evolution. Evolution cannot occur without three basic elements: variation in the starting population, the variation can be inherited, and the mutations impact reproductive likelihood. Evolution combines…