Skin color

Abstract

Skin color in humans varies by latitude and the intensity of ultraviolet radiation (UVR). Darker skin contains the natural sunscreen, eumelanin, which protects against multiple deleterious effects of UVR. When modern humans dispersed out of the Old World tropics, they evolved depigmented skin under natural selection in order to make possible the production of vitamin D in the skin under conditions of low and highly seasonal UVB. Similar skin colors have evolved numerous times independently under similar UVR conditions, and skin color thus cannot be used as a marker of unique genetic identity.