Why Evolution is True [Hardcover]

Jerry Coyne is a bit annoyed that it was necessary to write this book. I am glad he got annoyed enough to write it. In part he is writing against the intelligent design movement, and against creationism and he shows the flaws in these viewpoints not with rhetoric, but with well chosen evidence.

The book is a powerful and straightforward account of evolution showing the strength of the theory, its ability to make predictions, and giving many examples of the evidence on which evolution is based. After reading the book you have a good idea of what evolution is about, and what fields of study it applies in. Coyne is clear that evolution is a theory in biology of great explanatory power. The key idea is that of descent with modification.

He is also clear (in his final chapter evolution redux) of the limits to evolutionary thinking. Good scientists know what they know, and also have some idea where their knowledge stops. Coyne demonstrates this ability well. By doing this he becomes a far better advocate for evolution than Dawkins.

Evolution is not an ontological or moral theory. You can derive no moral lesson from evolution- it just is (p253). David Hume pointed out that deriving an ought from an is is usually to make a specious argument. The fact that the idea of evolution as progress has been misused by many is not an argument against evolution. It is an argument against the misuse of ideas.

Coyne (p248)describes that, "There is an increasing (and disturbing) tendency of psychologists, biologists and philosophers to Darwinize every aspect of human behaviour, turning its study into a scientific parlour game." He liberates us (p250)from some of the genetic determinism that sometimes accompanies evolution, "There is no reason, then, to see ourselves as marionettes dancing on the strings of evolution. Yes certain parts of our behaviour may be genetically encoded, instilled by natural selection in our savanna-dwelling ancestors. But genes aren't destiny...."genetic" does not mean "unchangeable.""

Coyne liberates evolution from its role as chief evidence for atheism.(pxix) "Nor must it promote atheism, for enlightened religion has always found a way to accommodate the advances of science. In fact, understanding evolution should surely deepen and enrich our appreciation of the living world and our place in it." Denis Alexander makes a similar point in his recent book,"Creation or Evolution:Do we have to choose."

This book does have one notable omission which arises because it sticks closely to the facts. There is no account of how the first cell ever got started, maybe because there is not yet any great evidence for how this happened. So far as I can understand evolution it describes the mechanisms of relationship between ancestors and descendants, but the tracing back of ancestors can only go back so far- to some original reproducing cell.

This book is timely this year. It's a great account of how evolution works from its 6 basic principles namely evolution (genetic change over time), gradualism, speciation, common ancestry, natural selection, and non selective mechanisms of evolutionary change. The basic principles have clear starting points and consequences which are observable or at least, inferable.

It puts evolution in a sensible context, and shows where, and to what, it sensibly applies. It is a welcome book this year and it puts the theory of evolution centre stage on its own merits, and not as a means to advocating for other ideas. Sensible, tolerant, encouraging and provoking further thought. Very scientific. Highly recommended.

"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.

That loudmouth Daily Mail journalist Melanie Philips once opined that evolution is a theory, not a fact. She meant presumably that evolution is 'speculation': that the evidence as it stands does not lean toward creationism or Darwinism. Hence, on the evidence there is, it is equally reasonable to opt to `believe' in either.

There are a lot of people out there who would agree with her. They need read Jerry A. Coyne's book which tackles the misunderstandings about Darwinian theory head-on. Evolution is indeed a theory, but that does not make it speculation. As Coyne explains, in science a 'theory' is much more than speculation about how things are: it is `a well thought-out group of propositions meant to explain facts about the real world.' Second, for a theory to be scientific, as opposed to mere speculation, it must be `testable and able to make verifiable predictions' and, third, `the scientific theories can be tested against other theories (pp 15-17).

What facts, then, support the theory of evolution - what predictions does it make that have been confirmed? Here are a few salient examples Coyle offers.

First of all there is the movement from simplicity to complexity. If life has evolved ever greater complexity over eons of time, the theory predicts that the fossil record should show greater and greater complexity over time. The oldest layers of rocks contain simple fossils, younger layers more complex examples. Evolution predicts simple organisms evolved before complex ones, with transitional fossils between simpler and more complex fossils. The fossil record does indeed confirm this prediction (see page 30)

So take the largest mammal on Earth, the blue whale, the distant ancestor of which was a shallow-water dwelling hippopotamus. Fossil mammals have been found that existed 60 million years ago but no fossil whales exist at this point. These appear 30 million years ago. Therefore the theory predicts that the transitional forms from hippo to whale would appear between 60 and 30 million years ago. The transitional fossils have been found exactly as predicted, appearing between 60 and 30 million years ago.

If species didn't evolve, then there is no way their distribution on Earth would make sense. Marsupials like the platypus are not found outside Australia yet their oldest fossils, over 80 million years old, are not found in Australia but North America. The theory is that marsupials originated in North America and migrated southwards to Australia, reaching the tip of South America 40 million years ago and reaching the Australia around 30 million years ago. But how did they cross the South Atlantic? There was no ocean to cross: the continents were joined. The tip of South America was joined to what is now Antarctica, which in turn was joined to Australia. Marsupials migrated across Antarctica.

If all this is true, then marsupial fossils should be found in Antarctica, and they should be younger than those in South America but older than those in Australia. Scientists set out to prove just that and indeed did just that and they were of the right age, around 35 to 40 million years old (pp 102 - 103).

Perhaps the greatest anathema to creationists and intelligent designers is the idea that humans descended from `apes'. What is the evidence for this? When Darwin made this prediction, in The Descent of Man, in 1871, there was very little fossil evidence around to back this up - just a handful of Neanderthal bones. He made this prediction on the basis of anatomy and behaviour. But since then, starting with the discovery of the `Southern Ape Man' in South Africa in 1924 and `Lucy' in 1974, among others, the evidence has been coming in.

As the fossils become more recent, we should see brains getting larger, teeth smaller and posture becoming more erect and this is what has been confirmed. It's not possible with the existing stock of bones and fossils to trace a linear descent and this may never be possible, as all the links may never be found. But, as Darwin predicted, `fossils that start off ape-like ... become more and more like modern humans as time passes.' (p. 227).

But evolution doesn't just make predictions, it explains facts about the natural world, or retrodictions. We know about the alarming tendency of bacteria to develop resistance to drugs (see pages 139 -141). This is a result of random genetic mutation occurring in pathogens, enabling them to survive and replicate, thus producing resistant strains. Creationism and ID cannot explain this phenomenon but evolution via natural selection can.

So when Coyle says evolution is true, he means the major tenets of the theory have been verified. This is not the same thing as saying it's not a fact because some mysteries remain unsolved.

Gaps in evolution do not mean that the entire theory has no foundation or is just speculation. Moreover over time the gaps are becoming fewer. We know that birds came from dinosaurs. They were not created out of thin air. We have evidence of the evolution of complexity in the eye, with many types of eye, at various levels of complexity, all around us. The precursors of complex biochemical processes such as clotting have been identified in invertebrates (p 151).

But still the existence of gaps allows proponents of ID to attempt to refute the theory. If there is complexity, and it is not entirely understood, then this is evidence for supernatural intervention. But this is simply a `God of the gaps' argument and explains and predicts nothing. There is no way that this can be verified. It makes no sense whatsoever to explain facts about nature by appealing to something that is outside nature. This to me is the fatal flaw that undermines all appeals to ID: the idea is incoherent.

Further observation about the facts of the world undermines the plausibility of ID.

Natural selection is a tinkerer, not a precision engineer. It works with the material it has. So some adaptations maximise reproductive fitness but are otherwise a disadvantage to the organism concerned. The peacock's tail is fantastically well-adapted for attracting mates but also predators. Female sea turtles dig their nests on beaches with flippers, an arduous process. It would be better if they had shovel-like flippers but this would mean they couldn't swim very well. Selection involves trade-offs (see page 13).

An intelligent designer could resolve this by giving the turtle an extra pair of retractable shovel-like limbs, or maybe giving the peacock a tail it could unfurl away outside mating season. Natural selection cannot do either of these things. It can only work with the existing framework but an all-powerful creator or designer by definition should not be limited by structural flaws.

Percy Bridgman, Harvard Professor of Physics and tutor of Robert Oppenheimer, once remarked: `Scientists aren't responsible for the facts that are in nature. If anyone should have a sense of sin, it's God. He put the facts there.' How indeed to explain these facts? Not all of them pretty facts, either.

We've seen how drug-resistance bacteria evolve. Is the creator creating new resistant strains out of nothing or is the designer tweaking microbes' DNA to develop resistance? How can we explain the existence of parasites like tapeworms? Are these the creations or the design of a benevolent deity? Why have 99% of species gone extinct? Is this really evidence of ID?

It is sometimes said that scientists are proselytisers and evangelicals for atheism and materialism. This is way off mark. All scientific proof is provisional. New data may conceivably undermine Darwinism. The theory of evolution would not survive if fossils of Cro-Magnon were found in the same layer of rock as a Tyrannosaurus Rex. If this happened, this would refute the entire theory. But the theory is supported not because of a dogmatic refusal to countenance other possible theories but because the data support the theory.

It is therefore false to say that evolution and creationism are both `faith positions', if by this it is meant that it is equally reasonable to believe or teach either position based on the evidence available. The evidence out there does not lean equally either way: it leans one way - and overwhelmingly so.