Question

what ecological conditions favored evolution of dark skin?

Answer 1

In the tropical areas, the amount of sunlight received is higher than temperate and polar regions. High amount of sunlight is associated with high amount of deleterious UV light which affect our skins. UV light cause folate depletion and also causes mutation in DNA by forming thymine dimer. Natural selection operates and it leads to development of dark skin which contain high amount of melanin pigment. This melanin pigment protects us from deleterious effect of sunlight and helps us to get rid of damaging effect of UV radiation. High amount of UV in the tropical and subropical areas of earth induce melanogenesis in skin that produce high amount of melanin. Melanin absorbs UV light and dissipate 99.9% of absorbed UV. So ecological condition s such s high intensity sunlight with more UV radiation induce the evolution of dark skin .