The theory of evolution stands over modern biology as quantum mechanics and relativity do over modern physics. And few modern scientists are as widely familiar and celebrated as Darwin. Yet most of us remain less than entirely clear as to how evolution by natural selection works and a series of celebrated titles by such writers as Steven Jay Gould and Richard Dawkins do little to help, being each so partisan of a particular, contentious, view of the subject. Carl Zimmer draws together the entire history of the subject, from Darwin's original insights on the voyage of the Beagle, through the 'modern synthesis', which combined genetics with natural selection, to the Darwinian medicine and the 'selfish gene' debates of today. There is no comparably balanced and wide-ranging book available at present, let alone one that is as well and accessibly written. For all of us who lack a comfortable familiarity with this most influential of scientific ideas, an idea that has as many implications for our understanding of child-rearing, AIDS and the fate of the rain-forest as it does for the 'origin of species', this is an ideal introduction.