Dark Skin Evolved to Prevent Cancer in Early Humans: Study

Human skin evolved to a darker shade to protect against skin cancer, according to a new study.

A research led by Mel Greaves, professor of cell biology at the Institute of Skin Cancer, London, says cancer was one of the reasons for the evolution of black skin in humans in Africa about 1.2 million years ago.

Prof Greaves looked into the clinical data from 25 studies of skin cancer in Albinos in Africa. It was found that nearly 80 percent of people aged in their twenties or thirties from Africa- Tanzania and Nigeria developed skin cancer.

Albinism is a genetic disorder with low or complete absence of melanin in the skin, hair and eyes and that likely causes cancer during reproductive age.  According to Livescience reports, one in every 5000 people in sub Sahara Africa are affected with Albinism while in the United States it is seen in one out of 60,000 people. The findings also suggest direct exposure to sunlight increases vulnerability to skin cancer by 1000 times.

Prof Greaves said, "Charles Darwin thought variation in skin color was of no adaptive value and other investigators have dismissed cancer as a selective force in evolution. But the clinical data on people with albinism, particularly in Africa, provide a strong argument that lethal cancers may well have played a major role in early human evolution as an important factor in the development of skin rich in dark pigmentation - in eumelanin," reports MedicalNewsToday.

 Early humans shed hair and their pale skin was exposed to the harsh ultra-violet rays of the sun in Savanna and they evolved a melanin-rich dark skin that protects against cancer and damage to sweat glands and DNA. Their skin tone again changed from black to pale -light tone after migrating to Europe and East Africa   50,000 to 80,000 years ago.   

The study is published in the journal proceeding of the Royal Society B.