Originally Posted by frost

"The evolution of dark skin is linked intrinsically to the loss of body hair in humans. By 1.2 million years ago, all people having descendants today had the same receptor protein of today's Africans; their skin was dark, and the intense sun killed off the progeny with any lighter skin that resulted from mutational variation in the receptor protein.[3] This is significantly earlier than the speciation of Homo sapiens from Homo erectus some 250,000 years ago."