Videos are generally available for preview to non-members as short clips. Limited full-length titles are also available. Log In to view the full length title.
Human ancestors in Africa likely had dark skin, which is produced by an abundance of the pigment eumelanin in skin cells. In the high ultraviolet (UV) environment of sub-Saharan Africa, darker skin offers protection from the damaging effects of UV radiation. Dr. Jablonski explains that the variation in skin color that evolved since human ancestors migrated out of Africa can be explained by the tradeoff between protection from UV and the need for some UV absorption for the production of vitamin D.
