In prehistoric times, the ability of human kind to break these geographical barriers was small. These factors in racial variations had a direct impact on the next two. Climate has a direct effect on the pigmentation of races. In areas where peoples were exposed to more direct sunlight, skin pigmentation becomes increasingly darker. As stated earlier, the skin develops darker pigmentation to effectively protect itself from the sun.
Skin pigmentation is determined by the amount of melanin present in the skin.
The more the melanin the darker the skin. All races of the human species have this characteristic. There are isolated instantances of albinos, which are present in every race. In subtropical areas, where tree cover is scarce, such as the African Savannah, the people living there develop extremely dark pigmentation. In European areas, the cloudy cover enabled the people to survive without this quality.