Asked by: Dan Drake, Brighton
The apes that we’re descended from probably had pale skin under their dark fur, just as modern chimpanzees have now. Dark skin evolved around a million years ago as our ancestors moved from the forest to the savannah and began to lose their fur. At equatorial latitudes, dark skin protects from sunburn, but it also preserves folate, which is essential for making DNA and is destroyed by the Sun’s UVA rays. Further north, the UVA exposure drops and dark skin isn’t so important. At very northerly latitudes it can actually be a disadvantage because it blocks the production of vitamin D3, needed for strong bones and teeth.
In general, the farther north you go, the lighter the skin of the indigenous peoples. The Inuit and Yupik are exceptions, they’ve retained their dark skin, despite getting hardly any sun at all, because they get all the vitamin D they need from their fish diet. Some studies have shown that there is also a sexual selection factor, whereby white skin is seen as more desirable in women. This occurs in almost all cultures, even those with no history of European imperialism and where the natural population is dark-skinned. It’s not clear why this should be, but it may have helped to drive the evolution of white skin.