Resumen de A million years of changing skin colour
Skin has varied greatly among humans for at least the last 900,000 years. So concludes an analysis of skin pigmentation in people from several regions of Africa. The results suggest that some particularly dark skin tones evolved from paler genetic variants, underlining how deeply flawed the racist concept of people with whiter skin being "more advanced" is. Nicholas Crawford and Sarah Tishkoff at the University of Pennsylvania in Philadelphia recruited around 1500 ethnically and genetically diverse volunteers living in Ethiopia, Tanzania and Botswana for their study. Each person gave a DNA sample and had their skin pigmentation measured. The data allowed the team to find eight sites in the human genome that are particularly associated with the level of pigment present. Together, these sites account for about 30 per cent of the variation they found in skin tone among the volunteers.
