Evolution of Skin Color

With all of our discussion about race and skin color over the past few weeks I feel the need to understanding what skin color is and where it came from. When we discuss how organisms evolve to we must discuss the works of Charles Darwin. Darwin studied evolution and is famous for his writing On the Origin of Species. What is interesting about this book is that he doesn’t actually discuss the evolution of human beings.

UV map

One of the most observable differences between people is skin color. Darwin being an observer of the natural world realized that darker skinned people came from areas around the equator while lighter skinned people came from areas closer to the geographic poles. Darwin stated in The Descent of Man that this change in skin color had nothing to do with the climate of the area.

Fast forward to the modern day…

NASA satellites are able to observe and mark data of phenomenon that occur on the Earth. These satellites have marked the UV hot spots all over the Earth. The hottest of spots are those that have the most direct sunlight; the areas that are found around the equator. Our research has shown that the earliest of humans were found high UV environments. The earliest humans all had high levels of skin pigmentation because of the areas that they lived in. We all share in that history.

melanin

The UV B light is used by our bodies to produce vitamin D which allows us to have strong bones. We also have been able to produce melanin. Melanin has protected us by being a natural sunscreen against the destruction of DNA and folate that is caused by UV B radiation. At this point humans moved.

As we moved the type of UV radiation has changed. UVB does not reach the surface. It is dissipated through the atmosphere. The UVA that does come through does not allow the bodies to produce vitamin D as the UV B does. In order to produce the vitamin D and B the body had to adapt by reducing the amount of melanin that the body produces. As we keep moving, our skin color is no longer adapted to that environment. Lighter skin colors have to worry about skin cancer in the higher UV exposed areas. Those of darker skin colors have other health issues to deal with such as vitamin D deficiency.

albinism

We haven’t even begun to discuss the social ramifications of this particular adaptation. We need to understand that there are no social ramifications unless we make it.

 

Want to learn more?
http://humanorigins.si.edu/evidence/genetics/skin-color

http://evolution.berkeley.edu/evolibrary/news/140305_skincolor

http://www.pbs.org/wgbh/evolution/library/07/3/text_pop/l_073_04.html

http://www.livescience.com/34410-blue-skin-argyria-methemoglobinemia.html

http://www.economist.com/news/science-and-technology/21597881-homo-sapiens-became-black-beat-cancer-skinny-skin-colour

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