Humans living at latitudes far from the equator developed light skin in order to help absorb more vitamin D. People with light (type II) skin can produce previtamin D3 in their skin at rates 5–10 times faster than dark-skinned (type V) people.[19][20][21][22][23] People living far from the equator were under evolutionary pressure to develop light skin, which allowed more penetration of UV radiation and helped to produce more of the essential vitamin D.[6] The evolution of blond hair in some populations is related to the development of light skin, but in other populations is independent.