Gene study shows human skin tone has varied for 900,000 years

2019-03-04 06:09:01

By Colin Barras SKIN tone 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. For each of the eight sites, there existed a genetic variant associated with paler skin, and another linked to darker skin. Seven of the paler skin variants emerged at least 270,000 years ago. Four of these arose more than 900,000 years ago. The latest thinking is that Homo sapiens emerged in Africa about 300,000 years ago. The new findings mean that relatively pale skin tone variants predate the appearance of our species and have lingered in some parts of Africa ever since (Science, “People thought it was just light skin that has been evolving, but dark skin continues to evolve too” Three of the darker-skin gene variants appear to have evolved from variants linked with less pigment. This means some people with particularly dark skin – such as the Nilo-Saharan pastoralists of East Africa – gained the trait relatively recently, from paler-skinned ancestors. “People have thought it was just light skin that has been evolving,