on 22 January 2009
"Nothing in biology makes sense except in the light of evolution". That classic quote from the great Russian-American evolutionary geneticist Theodosius Dobzhansky is replete with far more truth now than when he uttered it in 1973. Thousands of scientists around the globe are using the principles of evolution towards understanding phenomena as simple as bacterial population growth to those as complex as the origin and spread of such virulent diseases as malaria and HIV/AIDS, and the conservation of many endangered plant and animal species. There is no other scientific theory I know of that has withstood such rigorous, and repeated, testing as the modern synthetic theory of evolution. The overwhelming proof of biological evolution is so robust, that entire books have been written describing pertinent evidence from sciences that, at first glance, seem as dissimilar from each other as paleobiology, molecular biology and ecology. But alas this hasn't convinced many in the court of public opinion, especially here, in the United States, who remain skeptical of evolution as both a scientific fact and a scientific theory, and who are too often persuaded by those who insist that there are such compelling "weaknesses" in evolution, that instead of it, better, still "scientific", alternatives exist, most notably, Intelligent Design creationism. Distinguished evolutionary geneticist Jerry Coyne's "Why Evolution Is True" is not just a timely book, but it is quite simply, the best, most succinct, summation I can think of on behalf of evolution's scientific validity.
No other modern evolutionary biologist has attempted to convey, with such excitement, and enthusiasm, a comprehensive, quite compelling, proof of biological evolution, unless you consider the notable literary careers of Coyne's graduate school mentors; Ernst Mayr and Stephen Jay Gould. Coyne's achievement is especially noteworthy for covering virtually every major evolutionary aspect of biology in a treatment that barely exceeds two hundred and thirty pages. In essence, "Why Evolution is True" can be viewed as an updated, modern rendition of Darwin's "On the Origin of Species", but encompassing those biological sciences, such as population genetics, molecular systematics, evolutionary developmental biology - better known as "evo - devo" - and, indeed, even paleobiology, which were unknown to Darwin; to put it bluntly, this is "one long argument" on behalf of evolutionary biology, told via Coyne's respectable, occasionally lyrical, prose and compelling logic.
Coyne asserts that there are six principles of evolution in the book's first chapter (having been preceded by two brief prefaces devoted to the nature of science and the ongoing intellectual threat posed by Intelligent Design creationism); evolution - which he defines as a species undergoing genetic change through time - gradualism, speciation, common ancestry, natural selection, and nonselective mechanisms of evolutionary change. These are indeed the very principles recognizable to anyone who has taken an undergraduate course in evolution, the key features of the Modern Synthesis Theory of Evolution; in other words, modern evolutionary theory. And they are principles recognizable to those evolutionary biologists who concur with Gould's observation that current evolutionary theory is incomplete in explaining the origin, composition and history of our planet's biodiversity; scientifically testable principles unlike those alleged to exist for Intelligent Design and other flavors of "scientific" creationism. In the book's remaining nine chapters, Coyne offers persuasive evidence on behalf of these principles from the fossil record, from the biogeography of plants and animals, from molecular genomic data, and other aspects of biology, discusses the importance of sex in driving evolutionary change, and the process of speciation itself.
There is much worthy of praise in Coyne's elegantly terse tome in defense of biological evolution. His fossil record chapter (Chapter Two) compellingly recounts the evolution of primitive tetrapods from bony fishes in the late Devonian, the mid Mesozoic evolution and early radiation of birds from their feathered theropod dinosaur ancestors, and the early Cenozoic evolution of whales from primitive ungulates distantly related to rhinos and tapirs. He demonstrates persuasively (Chapter Three) how humans and other animals are so poorly "designed", that their "designs" bear ample witness against the existence of an Intelligent Designer. His superb treatment of biogeography (Chapter Four) echoes the literary elegance of Darwin's prose, and reminds us of the stark differences between so-called Intelligent Design "theory" and evolution in making testable, verifiable, predictions regarding both present-day and fossil distributions of plants and animals. In the book's finest chapter (Chapter Seven), devoted to speciation, Coyne - who is among our foremost authorities on speciation - offers a surprisingly comprehensive account that discusses not only the mechanisms of speciation, but also, of equal importance to biologists, how species are recognized and defined as distinct populations separated from others in space and time. But readers may find most moving, his poignant treatment of humanity as a biological species (Chapter Eight), and how evolution may still be driving the course of human evolution.
There is so much worthy of praise in Coyne's book, that it seems almost an afterthought to mention errors, omissions, and potential disagreements. The most glaring of these may be his insistence of gradualism as an important principle of evolution, since others, like his Stony Brook University colleague Douglas Futuyma, have recognized the importance of morphological stasis (Though he might contend vigorously and persuasively that to do so would be to recast the argument as one of evolutionary tempo, instead of mode.). But I am especially surprised by his omission of the significant role of mass extinctions in reshaping the composition and complexity of Earth's biosphere, not just once, but approximately seven times in the last five hundred-odd million years, which has garnered ample attention from past and current University of Chicago colleagues; paleobiologists David Raup, J. John Sepkoski, and David Jablonski, among others. By themselves, mass extinctions are the key episodes in the history of life on Earth still ignored by leading Intelligent Design creationists such as mathematician and philosopher William Dembski and biochemist Michael Behe; their very existence strongly refutes the inane assertion that life has been "intelligently designed".
"Why Evolution is True" belongs on the bookshelves of anyone interested in science. However, those who are skeptical of evolution's scientific validity, remain its intended audience. Any of them possessing an objective, open mind, should be persuaded by Coyne's terse prose and compelling logic. The evidence for biological evolution is quite overwhelmingly true; Coyne's slender book is a magnificent presentation of this proof.