Why Evolution Is True

Jerry A. Coyne has been a professor at the University of Chicago in the department of ecology and evolution for twenty years. He specializes in evolutionary genetics and works predominantly on the origin of new species. He is a regular contributor to The New Republic, The Times Literary Supplement, and other publications. His most recent book is Why Evolution Is True (Viking Penguin, 2009). A passionate defender of both science and Darwinism, he recently discussed the evidence for evolution, intelligent design, and religious skepticism with D.J. Grothe, an associate editor of Free Inquiry.

Free Inquiry: Your book focuses on the “facts of evolution.”

Jerry Coyne: Yes. I noticed when I was teaching over the years that there is a real lacuna of the facts. If you look at a textbook in the 1920s or the 1930s, they all begin with “These are the reasons we accept evolution,” with sections on the fossil record and other facts. Those passages have all but disappeared as evolution has become more entrenched as a biological science. Now, even professional evolutionists don’t seem to know what the evidence is. Many of them just take it on faith—well, not faith exactly but on the authority of their forerunners. So because the evidence is so interesting and also because its absence from the books may inspire creationist views, I thought it was time to publish the facts of evolution all in one place.

FI: Most people who are working in evolution don’t really know the evidence to support the claims, they are just taking it on faith? Doesn’t this admission fuel the ID argument that evolution is just something into which people are indoctrinated?

Coyne: I may have overstated that. Most evolutionary biologists aren’t aware of the extent and breadth of the evidence for evolution. Certainly, most of them can cite the fossil record and give an example like archaeopteryx, the intermediate between birds and dinosaurs, but there is a far greater reach of evidence. And very few evolutionists are acquainted with that reach. When you become an evolutionist, you assume that the scientists who went before you were right. And so you don’t spend a lot of time learning it, just as people who are studying physics or chemistry don’t begin their education with a long disquisition on how we learn that atoms are real.

FI: When some people hear the phrase “theory of evolution,” they may assume that this means evolution is not yet proven, that it is “just a theory.” But you argue that evolution has been undeniably proven. Should we therefore start calling it the “fact of evolution”?

Coyne: Well, I guess we could. But in science, “theory” means a general explanatory scheme meant to account for observations in the real world. The theory of evolution is not just that evolution happened but that it happened by natural selection, that lineages branched into many other lineages, that there is common ancestry, and that the whole process took hundreds of millions of years. Each one of these propositions has been vindicated by the evidence. So yes, you can call it the “fact of evolution.” But when you call it a fact, to the layperson that may be taken as “evolution occurred,” whereas the theory of evolution is more than that: it is a series of statements not only that it occurred but why it occurred and how it occurred.

FI: You say that there is so much and so many kinds of evidence for evolution that one would either need to be willfully ignorant or blinded by faith not to believe in it. So what kind of evidence is there? Does it all amount to just the fossil record, what we dig up?

Coyne: That’s certainly where you most easily see evolution occurring over time—you can line up all the fossils, hominid skulls for instance from 7 million years ago to the present, and actually see the changes for yourself. But there is far more evidence than just the fossil record: molecular biology, for example, in the presence of inactive, dead genes in the genomes of species that were functional in their ancestors; embryology, the appearance in transitory form of structures that don’t make any sense unless evolution had occurred; the existence of vestigial organs, like the nonfunctional wings of flightless birds; the distribution of species on the surface of the planet, called “biogeography,” only explained by evolution; and bad design, like a man’s prostate gland squeezing his urethra, which would not be there if there were a beneficent or wise designer that created organisms. The evidence for evolution pervades almost every area of biology.

FI: What is a single compelling factual statement about evolution for me to tell my creationist neighbor?

Coyne: That humans evolved from apelike ancestors and that we know this because we have a fairly complete progression of fossil remains from those apelike ancestors gradually changing until we get to modern humans. We can do this for any number of species. I just picked humans because its the one that’s most sensitive.

To hear the rest of D.J. Grothe’s conversation with Jerry A. Coyne, which focuses on Darwin’s motivations, the intelligent design movement, and the relationship between belief in evolution and disbelief in a deity, go to www.pointofinquiry.org


Jerry A. Coyne has been a professor at the University of Chicago in the department of ecology and evolution for twenty years. He specializes in evolutionary genetics and works predominantly on the origin of new species. He is a regular contributor to The New Republic, The Times Literary Supplement, and other publications. His most recent …

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