Richard Dawkins, Darwin’s latterday pit-bull, has a missing link. Or, rather, had. With the publication of his tenth book, The Greatest Show on Earth, Dawkins finally gets around to filling a conspicuous void in an evolutionary oeuvre that spans nearly forty years. As Dawkins himself explains, all his previous books primarily deal with the power of natural selection and simply assume that evolution has happened. Dawkins outlines the goal for his latest tome in the introduction:
Evolution is a fact, and this book will demonstrate it.No reputable scientist disputes it, and no unbiased reader will close the book doubting it.
That ostentatious declaration sets the bar high, but by the final flowery chapter, after over 400 pages of dramatic evidence, it is apparent that the author has successfully cleared the hurdle.
The book’s September 2009 release was just in time for the sesquicentennial anniversary of the publication of Charles Darwin’s On the Origin of Species, certainly no mere coincidence. In fact, Dawkins’s book shares many conspicuous parallels with Darwin’s first edition from 1859. Both have 14 chapters (including Dawkins’s appendix) and follow much the same outline for "one long argument" intended to establish the scientific case for evolution. Both begin by setting out the evidence for natural selection, first treating artificial selection in the origin of domesticated animals and plants and then moving to bona fide natural selection in the wild. Like Darwin, Dawkins next proceeds methodically to the ample evidence from the fossil record, from developmental biology, from biogeography, and finally from vestiges and other remnants of historical contingency. But Dawkins’s job is much easier than Darwin’s was, and it is correspondingly more compelling. Here in the 21st century, the evidence for evolution is indeed great, much more diverse and extensive than 150 years ago when Darwin wrote the Origin.
Chapter after substantial chapter, we are treated to the many independent, converging lines of evidence that all point to the same conclusion: the fact that "all living things are cousins". Dawkins devotes an entire chapter to geological dating, covering radioactive methods, tree rings, geological strata, and leading fossils, with a clear refutation of the oft-made charge that fossil dating is circular.
Dawkins really finds his stride in the fifth chapter, "Before our very eyes". Here Dawkins discusses several cases of evolution observed in real-time in both the lab and the wild, including the impressive Lenski experiments on twenty years of controlled bacterial evolution.
By the sixth chapter (on transitional fossils) one gets the feeling that Dawkins is really batting them out of the park, and he keeps on hitting homers for the rest of the book. Dawkins covers topics often given short shrift in other books of this kind, and his treatment of the modern molecular evidence, ranging from protein folding to molecular phylogenetics, is particularly satisfying. His consideration of the molecular clock and the neutral theory of evolution is especially useful and avoids some of the more common misconceptions that have persisted even in the primary literature.
I was singularly pleased to see David Penny’s formal test of common descent brought to a larger audience, where five independent protein phylogenies are shown to display statistically significant similarities — a result expected if the species harboring these proteins are genetically related. In the closing chapter, Dawkins deconstructs line by line, as if explicating a poem, the famous final paragraph of Darwin’s Origin. This unorthodox conclusion is perhaps the finest chapter of the book, touching on the universal genetic code, abiogenesis, thermodynamics, the RNA world, and the anthropic principle.
Stylistically, this latest offering harbors no surprises, and if you have enjoyed Dawkins’s previous books, you will not be disappointed with this one. Dawkins is the prince of scientific analogies and is uniquely adept at conveying difficult and complex scientific concepts by extracting otherwise arcane similarities from more familiar things. The embryonic development of an animal is likened to "inflating origami". Protein folding is compared to the spontaneous bunching of magnetic beads on a beaded necklace. If, over the millennia, you could hear the ticking of neutral fixations in the molecular clock, it would sound, according to Dawkins, like the random crackling of a Geiger counter.
Dawkins’s frustration with creationists and the excesses of religion are plainly sensed in this book, as in his others, and his indelicate remarks, though largely justified, will undoubtedly be offputting for many potential readers:
The history-deniers [Dawkins’s euphemism for anti-evolution creationists] themselves are among those that I am trying to reach in this book. But, perhaps more importantly, I aspire to arm those who are not historydeniers but know some ... and find themselves inadequately prepared to argue the case.
Flaws and quirks aside, Dawkins’s message will quite likely hit its intended target, as well as open some of the more hardened minds of evolutionary skeptics.
In a book on evolutionary evidence, it is hard to avoid a few nods towards debunking the common creationist fallacies. Nevertheless, unlike many other popular books that cover the evidence for evolution, this is not primarily a refutation of creationism or "intelligent design" arguments. Rather, Dawkins’s latest book is a positive commemoration of the triumph of a grand arching theory that has withstood the continuous onslaught of 150 years of new data, including the tsunami of molecular, genetic, and sequence data from the past fifteen years.
In the final analysis, The Greatest Show on Earth will take a deserved place alongside other "must-read" evolution books. No other book currently available approaches Dawkins’s comprehensive yet accessible treatment of the extraordinarily diverse and massive body of data that drives ineluctably to the same conclusion, the only conclusion that makes sense of everything in biology: that all the "endless forms" of known life share a common genetic kinship, as they have been, and are being, evolved.