The evolution of human skin color is an intriguing topic that breaks down racism when studied. The amount of melanin a person has in their skin is what determines their skin color. Melanin is a pigment that absorbs and scatters UV radiation. Differing needs of UV radiation is what caused different groups to have different amounts of melanin and therefore different skin colors (Jablonski & Chaplin, 2000).
Originally, dark skin evolved in order to protect against things such as sunburn, and skin cancer caused by UV radiation (Jablonski & Chaplin, 2000). The level of UV radiation is the highest around the equator because it receives the most sunlight. Accordingly, near the equator the use of melanin to absorb UV radiation is essential.
On the other hand, in places that receive less sunlight, such as the arctic circle, lighter skin evolved. Lighter skin increased the creation of vitamin D within the body. Vitamin D is produced in the skin when it is exposed to UV radiation. So when melanin scatters UV radiation, less vitamin D is produced. Vitamin D is essential to the body, so being able to produce vitamin D and in turn, having less melanin is very important (Holick, 2007).
To put it simply, in some places people needed more UV radiation to be healthy so their level of melanin increased. While in other places, people needed UV radiation to be healthy so their level of melanin decreased.
Jablonski, N. G., & Chaplin, G. (2000). The evolution of human skin coloration. Journal of Human Evolution, 39(1), 57-106.
Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine, 357(3), 266-281.
Evolutionary Anthropology 