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Light Skin: skin effect, skin biology, variation in human skin color?

Light Skin
Light Skin

which of the following statements apply to the variation in human skin color?

Light Skin- The differences in skin color of different races are related to their living environment. Since our Homo sapiens ancestors went out of Africa, various problems need to be solved during migration. One of them is to find a balance between resisting ultraviolet radiation and absorbing vitamin D.

African colors: What determines skin color?

Human skin color is the result of long-term evolution. The regions with intense ultraviolet light, areas with dark human skin and weak UV light, and light human skin. The difference caused by different environments is now apparent, but it has a lengthy adaptation process.

For the early humans living in Africa, initially, they could rely on their hair to resist ultraviolet radiation, but after the hair faded, the skin took on this task. If the skin absorbs too much ultraviolet light, human cells will be damaged. At this time, cells that can resist ultraviolet rays need to protect the human body. Such cells are melanocytes. The number of melanocytes directly affects the color of the skin, so early humans living in Africa had dark skin.

As human ancestors came out of Africa, the environment they faced has also changed, and the intensity of ultraviolet radiation has also changed. The dark skin that protects the human body in the high-intensity ultraviolet climate has become a barrier for the skin to absorb ultraviolet rays, especially those perennial Where the sun does not shine, dark skin makes it difficult for the body to synthesize vitamin D.

Vitamin D is quite important for calcium absorption. Long-term lack of vitamin D makes bones no longer healthy. So people living in these areas can only choose " "Fade" to absorb ultraviolet rays, ingest vitamin D, and get the calcium needed for survival. In the same race. Women tend to have whiter skin and are also associated with calcium.

Light Skin: Why are women whiter?

We know that the formation of fetal bones requires a large amount of calcium. These calciums need to be taken from the mother's body. If breastfeeding is used, the mother's body is still the primary source of calcium. From pregnancy to the end of lactation. A large amount of calcium is lost in the body and recovered. The interval may take months to six months. Modern people can supplement calcium in various ways, but for our ancient ancestors, we could only rely on the sun on.

As mentioned earlier, ultraviolet light can help the body increase the synthesis rate of vitamin D, and vitamin D has a vital effect on calcium formation. Therefore, for early human women, whitening them can better absorb ultraviolet rays, so that they can take in enough vitamin D to supplement the calcium lost due to fertility and breastfeeding offspring.

Although we often say "one cover one hundred ugly," there is no necessary connection between white and beauty. The animal world is not white, and males tend to look better than females, such as stags with large antlers, male peacocks with pompous tails, and male orangutan cheek pouches.
Darwin explained this phenomenon with sexual selection. On the one hand, males with "exaggerated" looks are more able to attract the attention of females; on the other hand, larger males often win in the struggle with other males.

Therefore, rather than being generally whiter than men for the sake of beauty, human women are better at giving sufficient calcium to future generations, and the characteristics that have evolved from this.


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