Re: why does the sun cause more freckles to appear on your skin?

The dark color of a freckle is due to a pigment called melanin that is produced in the skin by everyone except albinos. There is an inherited difference in the amount of melanin in different races, and also considerable variation within the same race. The function of the melanin is to absorb the harmful ultraviolet rays of the sun, reducing damge to deeper tissues in the body. So specialized pigment-producing cells in the skin, called melanocytes, make more melanin when we spend more time in the sun. This produces a tan when the melanin is evenly distributed within the skin. In many fair-skinned individuals, however, some melanocytes make more melanin than others. The area around these melanocytes gets darker than other parts of the skin, producing a freckle. The freckles tend to appear on parts of the body that are exposed to more light, like the face and shoulders.

Here are a couple of websites with information about freckles:

http://www.sfsu.edu/~shs/skin%20clinic/freckles.htm

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