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Why do people have different skin colors?
Question Date: 2000-10-17
Answer 1:

There are many different human skin colors around the world. Before the mass global migrations of people during the last 500 years, dark skin color was mostly concentrated near the equator, living mostly within 20 degrees of the equator. Lighter skin pigmented people lived progressively further away mostly in the northern hemisphere north of 20 latitude.Skin color varies from a very dark brown to yellow-pink. Researchers know today that skin color is determined by a complex structure of multiple genes.

Encoded in the genes are the pigments responsible for different color range:Carotene, Hemoglobin, and most importantly Melanin. Skin color is due mainly to the presence of melanin which comes in two forms: Pheomelanin produced by people with light complexioned skin, and Eumelanin produced by people with dark colored skin. In lighter skin, color is also affected by hemoglobin in theblood flowing close to the skin. Skin color is also affected by the presencecarotene.More importantly in determining skin color, people differ in the number and size of melanin particles in their skin.

The development of different skin pigmentation in evolutionary and is part of natures natural selection. Nature has selected for people with darker skin in tropical latitudes, where ultraviolet radiation from the sun is the most intense. Melanin acts as a protective biological shield against ultraviolet radiation. Melanin in the skin helps prevent sunburn and skin damage that could cause DNA changes and skin cancer. But melanin must not shield the skin completely. A certain amount of ultraviolet radiation (UVB) must penetrate the skin in order for the body to produce vitamin D, which is very important for our body. It is needed for the absorption of calcium for bone growth in order to maintain normal heart action and a healthy nervous system. Nature selects for less melanin when ultraviolet radiation is weak. This is why people who live in far northern latitudes have lighter skin. Having dark skin in this environment, is a disadvantage because it can prevent the body from producing enough vitamin D.

Answer 2:

We have different genes that determine how much color our skin cells make.The brown color comes from a molecule called melanin. And of course it depends on how much sunlight our skin gets - the ultraviolet light in sunlight causes our skin cells to make melanin.

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