Once they encountered baldnessthey evolved dark skin, needed to prevent low folate levels since they lived in sun-rich Africa.
Calcium is also necessary in adults to maintain normal heart action, blood clotting, and a stable nervous system. Vitamin D plays an additional important role in promoting the production of cathelicidin, which helps to defend our bodies against fungal, bacterial, and viral infections, including the common flu.
Hence, Harding concluded that the lightness of human skin was a direct result of random mutations in the MC1R gene that were non-lethal at the latitudes of Sweden.
There is also a strong correlation between the amount of sunlight that children are exposed to and whether or not they will develop multiple sclerosis as adults. Folate is derived from folic acid one of the B vitamins in our food.
It would be harmful if melanin acted as a complete shield. Generally, those who start out with darker skin color and more melanin have better abilities to tan. However, the progeny of those humans who migrated North away from the intense African sun had another evolutionary constraint: This is the case with arctic hares, which are white like snow in the winter and mottled black, brown, and gray similar to the rocky ground in their region after the snow melts in the summer.
This link takes you to an external website. A certain amount of shortwave ultraviolet radiation UVB must penetrate the outer skin layer in order for the body to produce vitamin D. Some Northwest Europeans have substantially lost the ability to tan as a result of relaxed natural selection.
In response, they produce melanin within a few hours of exposure. Biasutti prior to Fitzpatrick scale The following list shows the six categories of the Fitzpatrick scale in relation to the 36 categories of the older von Luschan scale: Chloasma describes skin discolorations caused by hormones.
It has also been shown to be one of the significant components of the skin color of modern Europeans through its PheLeu rs  allele that has been directly correlated with skin color variation in mixed-race populations. Exposure to sun[ edit ] See also: Sweet argues that based on cave paintings, Europeans may have been dark as recently as 13, years ago.
The same is true of albinos. Adequate vitamin D resources are needed to absorb calcium from the diet, and it has been shown that deficiencies of vitamin D and calcium increase the likelihood of various birth defects such as spina bifida and rickets.
Children growing up in tropical and subtropical regions rarely develop MS regardless of where their ancestors came from. Accordingly, the MC1R gene specifies the amino acid sequence in the receptor protein that relays through the cell membrane the hormone signal from the pituitary gland to produce the melanin that makes human skin very dark.
Too much ultraviolet radiation penetrating the skin may cause the breakdown of folate in the body, which can cause anemia. Mate selection preference and other cultural practices may also be partly responsible for this gender difference in skin coloration.
Both amount and type are determined by four to six genes which operate under incomplete dominance. Melanin Melanin comes in two types: Melanin is normally located in the epidermisor outer skin layer.
Different populations have different allele frequencies of these genes, and it is the combination of these allele variations that bring about the complex, continuous variation in skin coloration we can observe today in modern humans.Human Skin Color and New Marketing Strategy.
I consider they are doing a terrific job; but again even when they reworked the advertising message,?advertising focus is now on the message that. Some of the variation in human skin relationship to skin color are unknown.
New research by Nina of human skin color was. Oct 12, · Genes for Skin Color Rebut Dated Notions of of Pennsylvania and a co-author of the new vary tremendously in skin color. How can one best brand human skin? Ask New Question. How long should a metal tool be held on the human skin to make a good brand?
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