How much do we, who are alive today, differ from our most recent evolutionary ancestors, the cave-dwelling Neanderthals, hominids who lived in Europe and parts of Asia and went extinct about 30,000 years ago? And how much do Neanderthals, in turn, have in common with the ape-ancestors from which we are both descended, the chimpanzees? Although we are both hominids, the fossil record told us long ago that we differ physically from Neanderthals, in various ways. But at the level of genes and the proteins that they encode, new research published online May 6 in the journal Science reveals that...