Evolution Of Skin Color

Skin color, or skin pigmentation, is an evolutionary bi-product. The varying skin colors across the world is the human body's adaptive response to climate and UV exposure. The surface of Earth has does not have the same level of UV exposure at every spot. UV radiation varies, being strongest at the equator and lessening as you move closer to the poles.

Now there are different types of UV radiation, the type that is most vital for humans is UVB (ultraviolet B). Receiving UVB from sunlight stimulates our bodies to create Vitamin D, an extremely important vitamin (you need it for your bones, immune system, cardiovascular health and other bodily processes). However, the right amount is needed to stay healthy. Too much vitamin D can cause toxicity and too little can cause a myriad of health problems.

Our ancestors, the first homo sapiens, evolved in Africa, and Africa is in the zone that has the highest level of UVB radiation. UVB was not only plentiful for the bodies of our ancestors, it was far more than the body required. So evolved melanin. Melanin is the pigment that is skin color and it is a natural sunscreen.

Over time, different groups of these ancestors of our race migrated from high UVB zones to regions with little to no UVB. And then again, through evolutionary processes like natural selection, the bodies of our ancestors living in UVB deficient climates, shed their melanin in order for their skin to absorb the UVB that it could in order to survive. These migratory patterns occurred more than once, whereby groups of our ancestors moved from high UVB zones to low UVB zones and then back again. Over time, as humans spread across the globe, and permanently relocated themselves for substantive periods of time, the human skin color took on different hues - totally based on our bodily requirements for survival and climatic differences which affect that survival.

To hear all this and more in a more multi-fauceted format, here is an excellent video with Nina Jablonski, who is a scientist/anthropologist and an expert in her field. I highly recommend watching this: