Magazine article Science News

Evolution of Dark Skin Reconsidered: Melanin Could Have Protected Early Hominids from Cancer

Magazine article Science News

Evolution of Dark Skin Reconsidered: Melanin Could Have Protected Early Hominids from Cancer

Article excerpt

Common forms of skin cancer were Stone Age killers that prompted the evolution of dark skin among human ancestors in Africa, a controversial new analysis concludes.

Evidence gathered over the last 40 years shows that albinos in tropical parts of Africa and Central America, where people are constantly exposed to high levels of the sun's ultraviolet radiation, frequently develop skin cancer and die young, says biologist Mel Greaves of the Institute of Cancer Research in London.

Early members of the genus Homo in Africa were probably pale skinned and spent a lot of time hunting and foraging in direct sunlight, Greaves asserts. Researchers generally agree that the loss of most body hair helped hominids control body temperature in tropical savannas.

Nonmelanoma skin cancers probably killed many light-skinned early hominids before they could reproduce, he proposes in the April 22 Proceedings of the Royal Society B. Genes that produce dark skin capable of filtering UV radiation would have spread relatively quickly in populations that had much greater sun exposure throughout life than modern groups do.

"Skin cancer could have plausibly been the most potent selective force responsible for the emergence of black skin in ancient hominids," Greaves says.

Other researchers have rejected the idea partly because skin cancer doesn't kill many people today.

Ancient, largely hairless hominids probably had skin more like that of living African apes than like human albinos', remarks biological anthropologist Nina Jablonski of Penn State. Apes' pale skin, when exposed to sunlight, develops enough protective melanin pigmentation to enable tanning similar to that of light-skinned people today. Apes possess a gene variant that makes tanning possible, while human albinos don't. Early Homo species probably carried the gene and weren't as prone to skin cancer as Greaves assumes, Jablonski says. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.