Charles Darwin took 20 years to write his theory of natural selection: he produced On the Origin of Species only on learning that he was about to be scooped. Was he a chronic procrastinator? Or was he afraid of the reaction of his peers, who had scorned earlier books on the "transmutation" of species? A bit of both came into play, but as acclaimed science journalist Quammen ( Song of the Dodo ) shows, during those two decades, Darwin was busy conducting scientific research that would bolster his observations of the finches and mockingbirds of the Galápagos Islands. He raised pigeons and theorized that domestic varieties could be traced back to a species of wild dove. He floated asparagus seeds in saltwater to explain how plants moved from one continent to another. Quammen commences his portrait with Darwin's homecoming from his five-year trip on the Beagle and then focuses on how he gained enough confidence and evidence to publish a book that would displace humankind from its privileged position as a special creation. This often slyly witty book stands out among the flood of books being published for Darwin's bicentenary.