Melanin influences neural activity and mediates the conduction of radiation, light, heat and kinetic energy. As such, it is the subject of intense interest in biotech research and development
Melanin is formed as part of the process of metabolizing tyrosine (an amino acid). Melanin is formed in the skin by cells called melanocytes.
Not only is it responsible for skin color, it also gives hair and the iris of the eye their natural colors.
The purpose of melanin production is protect the nucleic acid of the cells, cell membranes, and proteins (collagen and elastin).
While melanin provides natural protection against the harmful effects of the sun's ultraviolet rays, it does not provide complete protection. Therefore, darker skinned individuals are still at risk, although they are generally better able to tolerate more lengthy exposure to the sun than lighter skinned individuals. Melanin's protection comes in the form of a tan that occurs when pigments enlarge in response to the ultraviolet radiation. This helps the skin to prevent sunburn damage, which can lead to cancerous melanoma. Cataracts have also been linked to sun exposure and less than optimum melanin levels. Too much ultraviolet exposure can also lead to anemia, neural tube defects in pregnant women, and decreased sperm production- a few possible results from folic acid levels being depleted.
Certain medical conditions are associated with the lack of melanin. Albinism, for example, is the absence of normal amounts of melanin in the body and can affect skin color, hair color, and/or eye color. It can also result in impaired vision, as melanin minimizes the number of light beams that enter the eye and permits the absorption of scattered light within the eye.
Darker skinned people are at a disadvantage in northern latitudes because they are incapable of synthesizing enough vitamin D from the sunlight. However, the dark-skinned Eskimos of Alaska haven't had to undergo the same reduction in pigmentation as others in such high altitudes because they eat a diet rich in fish and other seafood (which are high in vitamin D).