>> Skin Colour

The colour of skin depends primarily on a pigment called melanin. It is also influenced by the blood flow through the skin. Melanin is a pigment produced by special cells called melanocytes that manufacture packets of melanin called melanosomes and transfer them to the skin cells of the epidermis the keratinocytes.

Melanin pigmentation in humans is of two types. The constitutive colour is that which is genetically determined without the effect of sunshine. The other is inducible skin colour or tan as a consequence of sun exposure. Other factors can darken skin, some hormones e.g. in pregnancy can make the skin darken and some parts of the body are darker than others. In white people the darkest area is the upper thigh and the lower back is the lightest. In black people the abdomen is the darkest.

Melanocytes are found throughout the skin. There are roughly 2x109 melanocytes in the skin of an average person. The number of melanocytes in the skin is the same in all races. The difference in colour between Caucasoid, Mangoloid and Negroid skin is due to the number and arrangement of the melanosomes in the keratinocyte.

Melanin helps protect the skin against the effects of ultraviolet light, and tanning of the skin on sun exposure acts to increase that protection.

The superior sun protection of the black skin is therefore not due to more melanocytes but more melanosomes within the epidermis. Each individual should know how well their skin tans and how easily it burns because this is related to your risk of skin cancer from sunshine.