Why Evolution Is True
Jerry A. Coyne, Viking, 233 pages
It is perhaps fitting that the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of the publication of The Origin of Species should see the appearance of Why Evolution Is True by Professor Jerry A. Coyne of the University of Chicago. The work is a fine exposition of the theory of evolution, both clear and readable, and certain to make its mark in the ongoing debate. Prof. Coyne shows a familiarity with Creationist arguments (which he generally treats with contempt), and interacts with them throughout his own work.
The book, however, does not really change the nature of the debate. Prof. Coyne mainly rehashes the familiar arguments for evolution, most of them drawn from Darwin himself, whom Prof. Coyne quotes frequently and appreciatively.
Prof. Coyne insists that evolution is a "scientific fact." What is a bit confusing to us laymen is that scientists have their own criteria for establishing a "scientific fact." According to Prof. Coyne, a scientific theory is not necessarily something debatable. A theory is a set of propositions that explain a phenomenon. If the theory seems to explain adequately the evidence, and it is confirmed by subsequent discoveries, then it is considered a "fact." A scientist like Prof. Coyne knows this as the inductive method, unbiased, objective, and incontrovertible. A lawyer like Phillip E. Johnson recognizes it as an attempt to build a case on circumstantial evidence, an argument marked by circular reasoning and logical non sequiturs. There are two major weaknesses in this kind of argument. First of all, what if the evidence does not fit perfectly, if there is something that the theory cannot explain? And secondly, What if we cannot establish a direct causal link, the proverbial "smoking gun"? In this case the question is whether or not it is even possible for evolution to take place at all.
On the first question, let us take for example the fossil record. Prof. Coyne recites the familiar argument we have all heard before. But does the evidence really support the theory? Prof. Coyne posits a very slow process of gradual change. But that would seem to call for a vast continuum of transitional forms. What we actually see in the fossil record on the other hand is what we see today: distinct species or "discontinuities of nature," as Prof. Coyne call them. He is honest enough to make this intriguing statement: "When you look at animals and plants, each individual almost always falls into one of many discrete groups" (p. 169). That is the indisputable fact. But which theory does it support, evolution or creation? We think the latter.
On the second question, the question of causality, it is ironic that Prof. Coyne's most original contribution to the debate, his background in genetics, serves to undermine his own argument. In the second half of the book he discusses at great length how mutations enable species to adapt to their environments, sometimes even developing new features. But all of the examples he cites involve taking existing genetic material and modifying it or recombining it in some way to generate new characteristics in the species. Once it is apparent how this "microevolution" takes place, it becomes obvious why "macroevolution" cannot take place. Macroevolution, as Prof. Coyne conceives of it, would require passing over the genetic barriers that separate one species from another. Moreover, it would involve progressing from simple forms of life to more complex. As Prof. Coyne puts it, evolution is "the amazing derivation of life's staggering diversity from a single naked replicating molecule" (p. 233). Amazing indeed it is! It is impossible! This would seemingly require adding new genetic material where it did not previously exist. A mutation modifies an existing gene; it does not create a new one. Since each species has a set number of chromosomes, and the chromosomes come in pairs, in most cases the evolution from one species to another would require adding whole pairs of chromosomes. What Prof. Coyne has not explained is where the extra chromosomes would come from. Thus, while microevolution is quite explicable, macroevolution seems genetically impossible. The "murder weapon" in the case remains to be found.
Thus, in spite of Prof. Coyne's fine effort to produce a very readable and informative book, we are pretty much where we began: Darwinism is still vulnerable to most of the same criticisms that were leveled against it in Darwin's own day. In fact, in some ways, Prof. Coyne's explanation of the genetics involved makes the Theory of Evolution even less convincing. But the book is a useful primer for anyone interested in the controversy.
Robert W. Wheeler