Richard Dawkins' The Ancestor's Tale is just the sort of book that you would expect from the erudite biologist and popularizer of contemporary Darwinist thinking: cleverly arranged; of considerable heft, both literally and figuratively; and with limpid prose that delights as it informs. A big-picture look at the variety of life on Earth, its origin, and the genetics that make it all happen, the book's readers will suffer as well as benefit from the author's considerable experience: Dawkins frequently refers readers to his previous volumes, and he focuses much of his energy on long-running skirmishes within and outside the putative focus of the book.
Structured as a pilgrimage backwards in time from the present to the dawn of life, the book begins with recent human evolution. Our first rendezvous is with all other living human beings. At our second 'rendezvous,' we are joined by chimpanzees and bonobos, our nearest relatives. Only forty rendezvous points exist between modern humans and the origin of life, and Dawkins narrates them all in reverse chronological order with senses of wonder, of duty, and an intact sense of humor: The Ancestor's Tale is laced with puns and wordplay.
Modeled on Chaucer's Canterbury Tales, our fellow pilgrims have tales to share, stories that illuminate aspects of genetics, evolution, and how biologists think. The salamander's tale describes 'ring species,' animals that can interbreed with nearby neighbors, but who have lost the ability to mate successfully with more distant relatives. Dawkins writes that the salamanders
Are only showing us in the spatial dimension something that must always happen in the time dimension. Suppose we humans, and the chimpanzees, were a ring species. It could have happened: a ring perhaps moving up one side of the Rift Valley, and down the other side, with two completely separate species coexisting at the southern end of the ring, but an unbroken continuum of interbreeding all the way up and back round the other side. If this were true, what would it do to our attitudes to other species? To apparent discontinuities generally? (p. 303)
This and similarly informative sections are revelatory; they easily dissolve the misapprehensions and superstitions that have clotted around Darwinism and obscured what evolution entails.
Unfortunately, Dawkins cannot resist endless jabs at Creationism and its no-more-scientific progeny, Intelligent Design. It is unlikely that anti-evolution zealots will pick up and read this book; those who do are even less likely to finish it, given the author's hostility and rudeness towards his ideological opponents, as when he refers to creationists' "carefully impoverished imaginations." (p. 436) Dawkins seems to have taken the manifest correctness of his position as license to alienate every person who has been goaded into uncertainty by the well-rebutted arguments of Creationism; this is too bad, as The Ancestor's Tale contains more than enough evidence to refute the illogical and inconsistent position of its opposition, but it is unlikely to be seen, and still less likely to be given a fair shake, as a result of the author's attitude.
He is only somewhat kinder to supporters of "punctuated equilibrium," the theory that evolution proceeds at a stately pace but is occasionally interrupted by a frenetic burst of widespread change. Though superficially polite to its supporters, he does not seem to fully engage the arguments in favor of punctuated equilibrium, instead knocking about straw men, such as the supposed decoupling of micro and macro changes to organisms.
This is too bad; Professor Dawkins has quite a bit to offer. He has quite a talent for straightforward and illuminating disquisitions on topics that range from beavers' propensity for building dams to the HOX gene, which determines how embryos develop. His explanations of the 'clock' embedded in DNA, which allows us to estimate when two organisms diverged; of the primacy of genes over species in Darwinism; and his honest appraisal of the limits of our knowledge are all to be reckoned with. Dawkins' range is exhilarating, and readers who can overlook his occasional hectoring will find much to enjoy in The Ancestor's Tale.