Our human ancestors only evolved black skin after losing all their hair, study claims A) Dark skin appeared a million years ago to stop ancestors dying of cancer B) Previously, they would have had pale skin under their hair C) New evidence indicates the lethal effects of the sun’s rays may have exerted powerful selection pressure on early humans up to 1.8 million years ago Cancer may have driven the evolution of black skin early in human history, a study suggests. Scientists believe dark skins appeared more than a million years ago to prevent our African ancestors dying from skin cancer. The change occurred after ancient humans shed most of their body hair and ventured out into the sun-drenched African savannah. Previously, they would have had pale skin under their hair. New evidence indicates that the lethal effects of the sun’s rays may have exerted powerful selection pressure on early humans between 1.2 and 1.8 million years ago. Only those individuals with darker, more protected, skin would have escaped dying young from skin cancer and been free to pass their genes onto future generations. The theory has been rejected up to now because it was thought skin cancer rarely killed people at a young enough age to affect reproduction. But new evidence points to the fact that albino black people from parts of Africa with the highest exposure to ultraviolet radiation from the sun almost all develop skin cancer and die young. Lead scientist Professor Mel Greaves, director of the Centre for Evolution and Cancer at The Institute of Cancer Research in London, said: ‘Charles Darwin thought variation in skin colour was of no adaptive value and other investigators have dismissed cancer as a selective force in evolution. Source: dailymail.co.uk/health/article-2567715/Early-humans-evolved-black-skin-protect-against-skin-cancer-evolution-study-claims.html
Posted on: Tue, 04 Mar 2014 10:39:45 +0000
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