Skin cancer might have led to dark skin color in early humans, a study suggests.

It is known that people with black or brown skin have low risk of skin cancer. However, biologists weren't sure whether skin cancer was directly linked to the evolution of dark skin in humans.

Early humans in Africa lost nearly all body hair and developed skin rich in eumelanin around 1.2 and 1.8 million years ago. Melanin not only protects against skin cancer, but also prevents damage to the sweat glands and helps preserve folate, which helps prevent brain damage in babies.

The new study paper by Professor Mel Greaves at The Institute of Cancer Research says that dark people with albinism- a condition that prevents production of melanin- have higher risk of dying early due to skin cancer.

People affected with albinism inherit altered versions of genes, which lead to inadequate production of the pigment melanin. These people have little or no pigment in their eyes and are known to be at a higher risk of several health complications.

The condition is linked with skin cancer in tropical regions where the exposure to Ultraviolet radiation is high. Albinism is common in modern Sub-Saharan Africa where it affects about one in 5,000 people whereas the condition is seen in one in every 20,000 people in the U.S., according to Livescience.

In the present study, Greaves looked at data on albinism in Africa and found that most of the individuals with the condition developed skin cancer during their 20s, Livescience reported. The risk of developing skin cancer is 1,000 times greater in people with albinism in certain parts of South Africa than dark people.

This  might be the reason early humans evolved dark skin, said Greaves.

 "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," said Mel Greaves, Director of the Centre for Evolution and Cancer at The Institute of Cancer Research, London.

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