Jared Diamond

Out of 30,000 or so genes in the human genome, an estimated 6,000 genes exist as different versions (known as alleles). The distinctions that we conventionally use to divide the species into races -- skin color, hair, and the shape of faces -- are controlled by only a few genes. The vast majority of variable genes do not respect so-called racial boundaries. There is far more variability within any given population of humans, than between populations. If all humans of earth were wiped out except s single tribe in remote New Guinea valley, the survivors would still preserve 85 percent of genetic variability of our entire species. ` Page 81