Book Review: Jerry Coyne's Why Evolution Is True

Introduction: Personal Reactions to Evolutionary Opposition

I understand that the theory of evolution contradicts the account found in the Bible and other holy texts, at least for those who take a literalist interpretive stance. However, given that most religious texts contain more significant internal conflicts of their own, I never fully understood why this particular theory provokes such visceral emotional responses. Intellectually, I know 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. Yet, because people understand that other scientific ideas once intertwined with biblical teaching have been proven incorrect without permanently damaging religious belief, I assumed that people would be more open-minded about modern scientific theories. On the contrary, the strong scientific support for evolution makes the choice to reject it seem like an aggressively anti-scientific stance — one that appears to bleed over into other areas of scientific belief among those who oppose it.

I believe that Coyne captures the essence of this opposition 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, others ineffably thrilling" (Coyne, p. xv). Furthermore, evolution connects humans to animals in a way that many find threatening, especially given the systemic use, mistreatment, and abuse of animals by people throughout history. 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 of humans and other apes sharing common ancestors proved equally controversial.

In many ways, this resistance is tangled up in religious perspectives — a theme Coyne explores throughout the book. The more fundamentalist a country, such as Turkey or the United States, the more likely its population is to resist the idea of evolution. Moreover, in the United States, even some people who personally accept evolution advocate for teaching creationism or intelligent design in science classrooms as an alternative theory, despite the absence of supporting evidence for creationism and the overwhelming evidentiary support for evolution.

Coyne's Definition of Evolution and Natural Selection

Coyne provides a comprehensive definition of evolution that explains both the theory itself and the role that natural selection plays in the evolutionary process. He states:

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).

This is a modern definition of evolution, informed by scientific discoveries that have helped establish the age of the earth relative to the ages of plant and animal species. When Darwin first proposed the theory, it was not yet grounded in an understanding of the earth's age and was not backed by as much fossil evidence. Instead, he began with the premise that plant and animal species change over time — a series of genetic changes that generally improve function for a specific environment.

One argument frequently made against evolution is 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 holds that members of a species best suited for survival in a particular environment will be more likely to reproduce, gradually making those traits more prominent in the population and altering the species' overall genetic makeup across generations. Certain events can accelerate this process, so some species may evolve much more quickly than others. Conversely, if an environment remains stable and a species is already well-adapted to it, one would expect little or no change to that species over time.

Probably the biggest barrier to demonstrating evolution is that it is generally not something people can observe personally. Antibiotic resistance in bacteria is one example of evolution that can occur within an observer's lifetime, but it is not something the average person will witness directly. This is why the fossil record is such an important element of the evolutionary argument.

The Fossil Record as Evidence for Evolution

Fossils provide evidence of animal species that previously lived in specific locations. However, fossils themselves are relatively useless without the means to date them. By attaching dates to specific fossils, scientists have been able to assemble a fossil record that traces evolution over time. The fossil record, while providing some of the strongest supporting evidence for evolution, is also used by some anti-evolutionists as a basis for attacking evolutionary science, citing gaps in the record. When one considers that a complete fossil record would require excavating literally every location on the planet — an impossibility with modern technology — it becomes clear that an incomplete record is inevitable.

Furthermore, it is critical to understand that not all remains become fossilized. As Coyne explains:

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 creature that becomes compressed into rock by the pressure of the sediments piling on top (Coyne, pp. 21–22).

This process necessarily means that fossils develop from only a very small percentage of all plants and animals of each species, and that some species may leave no fossil record at all. Therefore, gaps in the fossil record are to be expected and do not undermine the case for evolution.

Conclusion: The Cultural and Ethical Stakes of Accepting Evolution

Coyne concludes his book by observing that even when faced with overwhelming evidence, many people refuse to accept evolution. They are overwhelmed by the emotional consequences of acknowledging a common ancestry — not only with apes, but ultimately with all organisms on earth. I understand why this causes genuine ethical difficulty. Humans have a long history of exercising dominion over other animals, often with significant cruelty. I think that people who oppose evolution may not be as troubled by the idea of humans as animals as they are by the implication that animals may share meaningful traits with humans. This raises uncomfortable questions about the morality of humanity's assumed dominance in the natural world. It also prompts wondering whether, through further evolution, another animal might one day surpass humans in dominance. I believe that this fear — that humans will no longer be the world's dominant species — drives much of the resistance to evolutionary science, even though the slow pace of evolution means that any such development, if it were to occur at all, lies thousands or even millions of years in the future.

Works Cited

Coyne, Jerry. Why Evolution Is True. New York: Penguin Group, 2009.