With this book, Richard Dawkins returns to what he's best at: writing about evolution by means of Natural Selection (the eponymous Greatest Show on Earth). In it, he lays out the evidence for both evolution and Natural Selection in chapters very loosely reflecting those of Darwin's On the Origin of Species. But Dawkins has the advantage over Darwin of 150 years of additional research, so, as you would expect, his evidence is presented more decisively, with few of Darwins's characteristic caveats and double-negatives.
In several places, Dawkins presents evidence and invites us to imagine ourselves in the rôle of a detective arriving late at the scene. What would a detective, or any other reasonably logical person, conclude from such evidence? This is a surprisingly effective rhetorical device, in that Dawkins does not invite the reader to challenge the evidence (which is pretty much incontrovertible), but asks them to think about what the evidence means. And any reasonably logical person can only conclude that Darwin was right: life evolves through a process of Natural Selection.
Not all of this book echoes Darwin's great work. There are several chapters devoted to topics which Darwin only touched on, or did not cover at all (because the evidence simply did not exist in Darwin's day). The most clear-cut of these is genetics. Before the advent of genetics in the second half of the Twentieth Century, generations of scientists had made a pretty good stab at grouping species into a Darwinian family tree based on their physical characteristics. When genetics came along, another tree of relatedness could be developed by comparing species' genomes. The two trees match each other to a remarkable degree of accuracy. Genetics provided independent, impartial proof that the Darwinian family tree was real, and not simply constructed in the minds of cladists.
Dawkins's writing is as clear and enjoyable as ever, and the individual chapters of The Greatest Show on Earth stand as excellent essays in their own right. But for some reason I can't quite put my finger on, I didn't think this book held together quite as well as many of Dawkins's earlier books. Perhaps he should have taken a lesson from Darwin and written a final chapter recapitulating what he had already said, drawing all of the arguments together. Having said that, the index card which I used as a bookmark while reading The Greatest Show on Earth is now covered front and back with tightly-packed notes: a sure-fire indication that a book has given me plenty of food for thought.