Dark coloured pigments (from black to brown with a red tinge) found in skin, body hair, hair, and the membrane of the eye. The amount of melanin in a person depends on several factors including inheritance, hormone concentrations, and certain diseases (e.g: albinos).
Role of melanin
The role of melanin is to protect the skin against ultra-violet irradiation from the sun which increases the ageing process and the carcinogenic process of skin cancer. The melanin pigments seem to lose their properties gradually during ageing. Not all scientists agree about this point. Some believe that the amount of pigment decreases with ageing. Others believe that it is a problem of distribution of the pigments in the skin that I believe explains the development of so-called age spots.