In 1978, NASA launched the
Total Ozone Mapping Spectrometer. In 1998, anthropologist
Nina Jablonski and her husband George Chaplin collected spectrometer data to measure UV radiation levels around the world and compared it to published information on the skin color of
indigenous populations of more 50 countries. The results showed a very high correlation between UV radiation and skin color; the weaker the sunlight was in a geographic region, the lighter the indigenous people’s skin was. Jablonski went on to prove that people living above the latitudes of 50 degrees have the highest chance of developing vitamin D deficiency. "This was one of the last barriers in the history of human settlement," Jablonski states. "Only after humans learned fishing, and therefore had access to food rich in vitamin D, could they settle regions of
high latitude." People living far from the equator developed light skin to produce adequate amounts of vitamin D during winter with low levels of UV radiation. Genetic studies suggest that light-skinned humans have been selected for multiple times.
[23][24][25]