The colour of a person’s skin depends on his environment. In regions with abundant sunlight, a dark skin colour is necessary to provide protection against the harmful UV rays. Light-skinned people in north Europe, where there is very little sunlight, do not need this protection. UV rays are not always harmful: they are needed for the formation of vitamin D, which the body needs for building bones. The darker the skin, the less sunlight can enter the skin and vitamin D formation is reduced. A dark skin may, therefore, result in Vitamin D deficiency in areas where there is not much sunlight.
