WEIT in TREE

In 1980, when I set out to write a defense of evolution against creationism [1], I discovered that there existed no book for general readers that described the evidence for, and nature of, evolution. The closest approximation was George Gaylord Simpson’s The Meaning of Evolution [2], which was really, as its subtitle stated, ‘a study of the history of life and its significance for man.’ In any case, it was then 31 years old and substantially out of date. Since then, the creationist movement, including its recent manifestation as so-called intelligent design (ID), has come to be recognized as a serious threat not only to evolution education, but also to science in general [3]. Yet although it sometimes seems that almost every evolutionary biologist is writing for a wide, nonprofessional audience on themes ranging from the fossil record to practical applications of evolutionary biology and the evolutionary dimensions of psychology, culture and the religious impulse, there still has not been a single book devoted to the simple task of showing readers the evidence for evolution and how it happens. We are fortunate that Jerry Coyne has exactly satisfied this need, with one of the very best and most important books on evolution for broad audiences in at least 50 years.

Although most of the themes of Coyne’s book will be familiar to evolutionary biologists, most instructors will learn some new examples or facets of familiar ones, or new ways of addressing questions. Moreover, Coyne carefully structures the evidence and theory, makes all the crucial points and presents the subject clearly, with allusions to human experience, sympathy for the uncertain or hesitant, and a scholarly yet almost conversational style that should make it easy for most people to read. The 254 pages of actual text are small in format, so the entirety can be read quickly. They are followed by notes, a glossary, an outstanding and valuable list of book and web resources, and a formal bibliography arranged by chapter. I might also note that Coyne, Drosophila geneticist although he be, delights in marshalling evidence from classical anatomy, embryology, systematics and the biogeography of diverse organisms, as well as contemporary molecular and developmental studies.

Coyne begins by describing the contemporary problem of opposition to evolution despite its importance and its status as ‘a theory that is also a fact’, and makes the usual and indispensable points about the nature of science, the testability of scientific hypotheses, and how hypotheses gain support from the correspondence between observation and predictions from a hypothesis. This is an important theme that he emphasizes throughout the book. The next three chapters, on the fossil record, ‘remnants’ (vestiges, embryos and bad design) and biogeography, present massive, well-chosen evidence for common descent and modification. Coyne emphasizes that fossils tell us of gradual change and of forms such as Tiktaalikthat demonstrate intermediacy, expected time of occurrence and evolution of new characters from ancestral ones. Vestiges, embryos and bad design include the multitude of morphological and molecular features that are inconsistent with any concept of ID but fully explicable from, and predicted by, evolution. And ‘the biogeographical evidence for evolution is now so powerful that I have never seen a creationist book, article, or lecture that has tried to refute it. Creationists simply pretend that the evidence doesn’t exist’ (p. 95). There follow three process-oriented chapters, on natural selection, sexual selection and speciation (Coyne’s special area of expertise), which all provide clear expositions of theory and evidence, and devastating points against ID. (For example, blood clotting, far from being ‘irreducibly complex,’ is based partly on the evolution of fibrinogen from a protein with a different function that was predicted, and then found, in sea cucumbers.) Chapter 8, ‘What about us?’, treats paleontological and genetic evidence on human evolution and briefly but clearly touches on patterns of genetic variation within and among human populations, and on gene–culture coevolution.

In the final chapter, Coyne acknowledges that evidence for evolution often cannot prevail against ‘the emotional consequences of facing [the] fact’ that we evolved from apes. He makes a good case that we need not fear ‘the beast within,’ the oft-imagined genetically determined selfishness and immorality that are thought to be inherent in ‘Darwinism,’ for the empirical evidence shows that we have immense capacities, unmatched by any other species, for empathy, kindness, and self-sacrifice. As Coyne notes, human sacrifice has disappeared, and ‘[i]n Roman times, some of the most sophisticated minds that ever existed found it an excellent afternoon’s entertainment to sit down and watch humans literally fighting for their lives against each other, or against wild animals. There is now no culture on the planet that would not think this barbaric’ (p. 251). Coyne admits that he cannot replace the comfort that so many find in conventional religion, but that he ‘can at least try to dispel the misconceptions that frighten people away from evolution and from the amazing derivation of life’s staggering diversity from a single naked replicating molecule’ (p. 253).

I can think of few changes that I would make beyond correcting a few proofreading lapses (Linnaeus’s great work was exactly a century after the date given) and minor errors. (Male stag beetles have sexually selected mandibles, not horns, and when will we ever stop hearing about the ‘peacock’s tail’? The historical contingency of evolution is exemplified by the variety of elongated display feathers among birds, which do include tail feathers in many other species, but also the flank feathers ofParadisaea birds of paradise, the secondary wing feathers of the great argus pheasant, head feathers in sage grouse and herons – and the back feathers, i.e. the train, of peacocks.) Coyne is clearly skeptical of most of evolutionary psychology while granting that some human universal characters might well be ancestral evolved traits, but I think one might make more allowance for the possible validity of hypotheses in this field (some of which do seem to make testable, and sometimes supported, predictions). Reassurances that evolutionary interpretations of human behavior are dubious will not allay fears of ‘the beast within’ if these interpretations prove to be well supported – and the empirical evidence Coyne presents, that we are not condemned by our genes to be unethical or immoral, should make such cautions unnecessary.

Why Evolution is True succeeds in being fully accessible to any reader who has even a vague idea of what DNA is. The publisher should issue an inexpensive paperback edition as soon as possible that should be stocked in every bookstore, sent to friends and relatives, and assigned as supplementary reading in introductory biology courses at both the high-school and university levels. It should also be widely translated. It is a book that needed to be written and needs to be read.