Washington: As people move more often and become more urbanized, skin color-an adaptation that took hundreds of thousands of years to develop in humans-may lose some of its evolutionary advantage, according to a Penn State anthropologist.About 2 million years ago, permanent dark skin color imparted by the pigment-melanin-began to evolve in humans to regulate the body`s reaction to ultraviolet rays from the sun, said Nina Jablonski, Distinguished Professor of Anthropology.Melanin helped humans maintain the delicate balance between too much sunlight and not enough sunlight. The pigment allowed enough ultraviolet radiation to produce vitamin D, a vitamin that helps the body absorb calcium, while protecting the skin from the intense ultraviolet radiation in the equator. Too much sunlight can cause the destruction of folate, which is also critical to cell division.As some humans moved away from the equator to places where the sun`s rays are not nearly as intense, they lost pigmentation, said Jablonski.
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