Evolving To Black?

Gemma Tarlach surveys research suggesting that dark skin evolved as an adaptive trait to protect against skin cancer:

Darker skin gives individuals much greater protection from UV light-induced skin cancer. Pale-skinned people are roughly 1,000 times more likely than individuals with dark skin to suffer from the three most common skin cancers. But for years, researchers believed the lowered risk was an incidental benefit, not one derived through the pressure of natural selection. Even Charles Darwin poo-poohed the notion that pigmentation could be an adaptive trait. A new study, however, finds evidence that skin cancer was in fact a driving evolutionary force for early hominids to have darker skin.

The findings were based studying people with albinism in equatorial Africa, which has the highest UV radiation exposure on the planet. The study, based on medical records, found that more than 80 percent of people with albinism in this region developed terminal skin cancer before the age of 30, or roughly at one’s reproductive height. Thus, researchers say, individuals with light skin were likely to die sooner— and produce fewer offspring — than those with darker skin.

(Photo by Garry Knight)