Medical advances mean that many people who once would have died young now live to a ripe old age. This has led to a belief that natural selection no longer affects humans and, therefore, that we have stopped evolving.
"That's just plain false," says Stephen Stearns, an evolutionary biologist at Yale University. He says although differences in survival may no longer select "fitter" humans and their genes, differences in reproduction still can. The question is whether women who have more children have distinguishing traits which they pass on to their offspring dermes.