Inside of every person’s, and animal cells there is Melanin. Melanin is produced by cells called melanocytes in the skin. It’s responsible for all the different color variations in not only skin but hair and eye as well. It is a pigment that comes in two different shades. Eumelanin is dark brown and black in color while Pheomelanin is more yellow and reddish in color. When a person has dark skin they have more eumelanin than someone with lighter skin. On the other hand someone with lighter skin has more pheomelanin than someone with darker skin. Skin color is a gradient, and the ratio of Eumelanin to Pheomelanin is the differences in that gradient.
The reason for this is an evolutionary advancement. The truth is, there is no such thing as race, we are all Homo sapien. We share 99.9% of our genetic code with each other. Our differences in skin color came from after our species came to be, making it a recent evolutionary trait. Biologists and Anthropologists alike have dated our species back to equatorial Africa. As we look at our cousins the great apes, we see that we have significantly less hair than they do. Because we no longer had the trees to protect us we had to run in order to survive, none of the other great apes had to do this. Hair loss was an evolutionary trait to improve our natural running ability, the less weight you have the faster you run. The lack of hair on our bodies had some drawbacks though, it left us vulnerable to the Ultra-violet Rays from the sun.
UV rays come directly from the sun. They are harmful in large amounts and prolonged exposure can cause a range of risk from sunburn to genetic mutations, aka skin cancer. Enter our old friend Melanin. Melanin does not just color our skin but it also helps protect us from UV rays. That’s why it is also found in animal hair. It protects our DNA by forming a shield that the rays cannot penetrate. The type of melanin that works best in blocking rays is the darker Eumelanin, which is why in places like equatorial Africa very dark skin is more abundant, because it is more useful in blocking the sun’s rays. With this in mind, let me say now, in the very beginning we all had very dark skin. It was not until us humans started to migrate around the globe that the gradient of different skin tones came to be.
I know that UV rays are harmful and cause skin cancer, but that’s only in small amounts. In fact we actually need this light to help make an important biological molecule, Vitamin D. Vitamin D does not come from the sun because our bodies make it, but we need the sun to give the skin a jump start into production. Without this essential vitamin diseases like Rickets form causing delayed growth and weakness of legs, back, and pelvis. In Africa where there is enough sunlight to get Vitamin D all the while protecting the skin from UV Rays, it’s more beneficial to have dark skin. On the other hand if you have places like Britain and other Northern European countries where there isn’t as much sun, it would be hard to have dark skin and receive the optimal amount of light for Vitamin D production.