| Besides skin colour, the colour of the hair is a relevant aspect of pigmentation. Although hair colour distribution is similar to skin colour distribution, the correlation of the two traits is far from perfect. The melanocytes present in hair follicles do not differ from those which supply melanin to the skin, but the activity of melanocyte is affected by the location in which it finds itself. Thus, hair colour may vary in different parts of the body as well. Individuals in Europe or North Asia may posses fair, sometimes even pale skin with black hair. On the other hand, some Melanesian, Australian, and Pygmy groups show blonde hair combined with dark brown skin. The possible hair colours in young adults are blonde, red, brown, and black. They are complicated by the presence of two different melanines, eumelanin and phaeomelanin, which together produce a variety of shades. Hair colour is not constant with age, as the amount of melanin increases with age before it abruptly decreases in old age. Children show a higher frequency of blonde and red hair in almost all places where lighter hair is present. This hair often but not always changes to brown shades until adulthood. In old age the hair turns gray or even white. In primates, hair graying has a social role, e.g. in gorillas white hairs on the back of a male denote full adulthood and indicate to the other gorillas that he is an individual to be respected. The typical hair colours of young adults are illustrated below. The map shows regions where a specific hair colour is common in native populations. On an individual level, other hair colours may appear in the black areas as well. |