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Geographical Variations
There is a great interdependence between the geographical reasons
behind skin color and the subjects’ exposure to sun. People from the
equator and surrounding regions have darker skin since the skin is
releasing more melanin. It does this to protect itself from sun burns,
damage of the sweat glands, skin cancers or any other conditions
caused by excessive exposure to ultraviolet rays.
The theories on dark skin are fairly set in stone, but when it comes to
light skin more than one theory is promoted by scientists. First, in the
absence of excessive exposure to sun, the skin does not need any
further protection, thus the production of melanin is diminished.
Second is the idea that mild climates offer the human body the
possibility to synthesize larger quantities of vitamin D, the substance
responsible for fighting rickets. To support this claim scientist suggest
that the difference between darker and lighter skin types resides in
only one gene, SLC24A5. In the case of Europeans studied, this
gene contained threonine-111 allenein proportion of 98.7 to 100%,
while in the case of Africans about 93 to 100% of that gene contained
alanine-111. Therefore, the pigment which gives the individual their
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