Race and the global map of human genetic variation

More on Cavalli-Sforza’s research into the genetic basis of race:

For any one gene, the map typically showed much more variation within than between human populations, just as Lewontin had found back in 1972. The pattern changed, however, when several gene maps were superimposed on each other. With data coming in from more and more genes, there emerged a distinct pattern of continental populations—the same ones that Cavalli-Sforza himself had once called “races.” This composite map would eventually appear on his tome The History and Geography of Human Genes (1994).