Adventures in Very Recent Evolution
http://www.nytimes.com/2010/07/20/science/20adapt.html?hpw Excerpts: Scientists from the Beijing Genomics Institute last month discovered another striking instance of human genetic change. Among Tibetans, they found, a set of genes evolved to cope with low oxygen levelsas recently as 3,000 years ago. This, if confirmed, would be the most recent known instance of human evolution.... Coloring the skin may sound simple, but nature requires at least 25 different genes to synthesize, package and distribute the melanin pigment that darkens the skin and hair. The system then had to be put into reverse when people penetrated the northern latitudes of Europe and Asia and acquired lighter skin, probably to admit more of the sunlight required to synthesize vitamin D. Several of the 25 skin genes bear strong signatures of natural selection, but natural selection has taken different paths to lighten people’s skin in Europe and in Asia. A special version of the golden gene, so called becau...