2017/01/07

Inuit live in very cold climates, why do they have dark skin?

Inuit dark skin determined by vitamin D rich diet


Excerpt 1: "But Inuit vitamin D intake wasn’t dependent upon the sun. They get all that they need from their diet, heavy on types of fatty fish that are naturally rich in vitamin D. The plentiful amounts of the vitamin kept them from developing less melanin. In fact, before milk was fortified with D, people living outside of Northern Canada and Alaska loaded their diets with fishy products, such as cod liver oil, to get their daily supplement. So despite their chilly climate and lack of sun exposure, it’s the Inuit diet that has kept them in their natural glow."

https://ghr.nlm.nih.gov/gene/MC1R

Excerpt 2:"The MC1R gene provides instructions for making a protein called the melanocortin 1 receptor. This receptor plays an important role in normal pigmentation. The receptor is primarily located on the surface of melanocytes, which are specialized cells that produce a pigment called melanin. Melanin is the substance that gives skin, hair, and eyes their color. Melanin is also found in the light-sensitive tissue at the back of the eye (the retina), where it plays a role in normal vision.

Melanocytes make two forms of melanin, eumelanin and pheomelanin. The relative amounts of these two pigments help determine the color of a person's hair and skin. People who produce mostly eumelanin tend to have brown or black hair and dark skin that tans easily. Eumelanin also protects skin from damage caused by ultraviolet (UV) radiation in sunlight. People who produce mostly pheomelanin tend to have red or blond hair, freckles, and light-colored skin that tans poorly. Because pheomelanin does not protect skin from UV radiation, people with more pheomelanin have an increased risk of skin damage caused by sun exposure.

The melanocortin 1 receptor controls which type of melanin is produced by melanocytes. When the receptor is activated, it triggers a series of chemical reactions inside melanocytes that stimulate these cells to make eumelanin. If the receptor is not activated or is blocked, melanocytes make pheomelanin instead of eumelanin."

My comment: The skin color is determined by epigenetic control of gene expression. Factors influencing the skin color are vitamin D levels in diet and vitamin D production induced by exposure to sunlight. Mutations are not the reason for human skin color variation. We all are the same kind of human beings. There is not such a thing as a human race.


Identical twins can have very different skin, hair or eye colours. Gene sequences don't determine these traits. Population genetics and the evolutionary theory tell serious lies. Don't get misled.

http://www.bionews.org.uk/page_621173.asp