Skin Color

When discussing different cultures, places and peoples, students often question why there are different skin colors in people around the world.

Wikipedia Entry: Skin Color

Melanin

• skin color is defined by the presence of "melanin" (wikipedia link)
• an enzyme triggers malanin production which defines skin, eyes, and hair coloration

Skin Color

• human skin tones range from black to pinkish-white
• white skin allows coloration of blood vessels below the skin to show through, which gives the pinkish coloration
• skin darkens from exposure to sunlight
• sunlight exposure causes the skin to produces Vitamin D

Evolutionary Explanation

• one theory of skin coloration is that humans adapted to sunlight exposure with lighter or darker skin depending on the environment

Eskmos

• if skin color is an environmental response, why, then, could Eskimos survive in Arctic regions without or with little sunlight much of the year and with less intense sunlight generally? An explanation may be that Eskimo populations derived much of their diet from Vitamin-D rich seafood, so they did not require sunlight exposure to recieve Vitain D. Therefore, there was no adaptation to lighter skin in Eskimo populations.

Other Explanations

• Genetic
• according to wikipedia article, "Other hypotheses include protection from ambient temperature, infections, skin cancer or frostbite, an alteration in food, and sexual selection"

Body Hair

• theory of variations in body hair follow similar idea of skinc colorations as adaptive to climate
  • hotter climates = less body hair for easier cooling against heat
  • colder climates = more body hair for protection against cold

External Articles

• Race Without Color, by Jared Diamond, Discover, Nov. 1, 1994
• Human Skin Color Variation from Smithsonian Natural History Museum

See Also

• Feel Short? Blame your ancestors by Jennifer Viegas, Discovery News, Feb 20, 2008