Why are there skins of different colors? – Science and the future

This article is taken from the monthly journal Sciences et Avenir – La Recherche #905-906 July-August 2022.

The history of skin color is a long journey. Both in time and space. When the first humans began to roam the surface of their planet in search of water and food 100,000 years ago, their skin began to darken near the equator as they approached the hottest lands. The way the body has found to protect itself from strong solar radiation is by releasing the protective pigment melanin.

A little UV light is needed

However, once they got further north, to colder areas, these researchers found that their skin was too dark. Indeed, if too much sun is harmful to the body, in particular by promoting the development of tumors, a small amount of UV rays remains necessary. By acting on the epidermis, they allow the synthesis of vitamin D, which promotes calcium absorption and bone mineralization. Thus, migrants from colder regions have seen their skin become lighter in order to capture some of that moderate sun and strengthen their bones.

Contribution of seafood and fish

The adventurers then continued on their way to the North Pole to form the native population of future Alaska and Canada. There they benefited from even less UV. But by consuming a lot of seafood and fish, they provided their body with the necessary vitamin D. Therefore, their skin was not thin enough to absorb the meager rays of the sun. On the other hand. They darkened, but this time to protect themselves from the very strong radiation reflected by the snow and summer ice.

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