I have written about war and peace, I have written about gender equality. I have written about people living in violence. Today, I am writing to the world about yet another human tragedy. I don’t know how bad racism is everywhere in the world, but I feel it is getting worse in America. I am an old lady, but I have a black hoodie that says peace on the front. When I wear it, I wear it with the hood up. I wear it that way for Trayvon Martin. I wear it because I realize that more people will look at it on the body of a 5’2″ blonde white woman. I wear it because my grandfather told me about the Holocaust when I was nine years old. He gave me a book of photographs in black and white of the piles of dead Jews, Poles and Gypsies. He sat…
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Should human adaptation be the reason to be biased against another human being?
Human Adaptation : http://en.wikipedia.org/wiki/Melanin
The most recent scientific evidence indicates that all humans originated in Africa, then populated the rest of the world through successive radiations. It seems likely that the first modern humans had relatively large numbers of eumelanin-producing melanocytes. In accordance, they had darker skin as with the indigenous people of Africa today. As some of these original peoples migrated and settled in areas of Asia and Europe, the selective pressure for eumelanin production decreased in climates where radiation from the sun was less intense. Of the two common gene variants known to be associated with pale human skin, Mc1r does not appear to have undergone positive selection, while SLC24A5 has.
As with peoples having migrated northward, those with light skin migrating toward the equator acclimatize to the much stronger solar radiation. Most people’s skin darkens when exposed to UV light, giving them more protection when it is needed. This is the physiological purpose of sun tanning. Dark-skinned people, who produce more skin-protecting eumelanin, have a greater protection against sunburn and the development of melanoma, a potentially deadly form of skin cancer, as well as other health problems related to exposure to strong solar radiation, including the photodegradation of certain vitamins such as riboflavins, carotenoids, tocopherol, and folate.
Melanin in the eyes, in the iris and choroid, helps protect them from ultraviolet and high-frequency visible light; people with gray, blue, and green eyes are more at risk for sun-related eye problems. Further, the ocular lens yellows with age, providing added protection. However, the lens also becomes more rigid with age, losing most of its accommodation — the ability to change shape to focus from far to near — a detriment due probably to protein crosslinking caused by UV exposure.
Recent research by J.D. Simon et al. suggests that melanin may serve a protective role other than photoprotection. Melanin is able to effectively ligate metal ions through its carboxylate and phenolic hydroxyl groups, in many cases much more efficiently than the powerful chelating ligand ethylenediaminetetraacetate (EDTA). Thus, it may serve to sequester potentially toxic metal ions, protecting the rest of the cell. This hypothesis is supported by the fact that the loss of neuromelanin observed in Parkinson’s disease is accompanied by an increase in iron levels in the brain.