Skin Color

The colour of the skin varies greatly among races and individuals. Skin colour depends mainly on the amount of the brown pigment melanin produced in the skin. Melanin is formed by the melanocytes in the epidermis. All people have about the same number of melanocytes. However, the melanocytes of dark-skinned people produce more melanin than do those of light-skinned people. The amount of melanin produced in each person's skin is determined mainly by heredity. However, exposure to sunlight increases the production of melanin, causing light skin to tan. In some cases, melanin builds up in small spots, forming freckles. Most freckles appear on the face and hands. Exposure to sunlight may increase the number of freckles.

As someone grows older, the melanocytes produce melanin at uneven rates, which causes some areas of the skin to remain light and others to darken. These dark spots are sometimes called age spots or liver spots. As a person ages, the skin also becomes thinner and drier and so starts to wrinkle and turn scaly. In addition, the skin of an old person bruises and chaps more easily and heals more slowly.