Human genetic variationRace and geneticsand Human genetic clustering The understanding of the genetic mechanisms underlying human skin color variation is still incomplete, however genetic studies have discovered a number of genes that affect human skin color in specific populations, and have shown that this happens independently of other physical features such as eye and hair color. 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.
In this paper I will discuss the importance of melanin in its role in the human biological system and how it relates to the natural selection of suitable human life according to geography and environment.
Human pigmentation is influenced by hemoglobins within blood vessels in the skin, carotene and melanins. Melanin, the basis of pigmentation, can be found in the forms of eumelanin and phaeomelanin.
Eumelanin is the brown-black pigment located in the skin, hair, and eyes. Phaeomelanin is a yellow to reddish-brown pigment found in small quantities within the skin, eyes, and red hair.
Because of these two pigments, to a greater or lesser degree, we have the variation in human pigmentation that is seen today. Melanin is the product of cells located within the skin called melanocytes.
The function of melanocytes is to manufacture the pigments eumelanin and phaeomelanin. Eumelanin, which is more photostable than phaeomelanin, is the main product of the melanocytes. In melanin, various chemicals, under the influence of enzymes, build a very stable compound that is distributed throughout the body of pigmented peoples.
In addition, melanin has been found in 1,year-old mummies and in extinct mammoth skins, according to Daniels et al. After production, melanin is packaged in membrane bodies called melanosomes. Dark skin has large melanosomes that are in a single state and also contains more melanosomes than lighter skin such as in Europeans.
Most Asian skin, on the other hand, has smaller concentrated groups of melanosomes, whereas European skin has the smallest melanosomes, which are combined into bound materials.
The spacing and amount of melanosomes are what gives the appearance of skinSeveral hypotheses that assign a key role to natural selection have been proposed to explain the global distribution of human skin pigmentation, such as photoprotection, protection against low vitamin D levels and protection against folate deficiency.
Melanic pigmentation is advantageous in many ways: (1) It is a barrier against the effects of the ultraviolet rays of sunlight.
On exposure to sunlight, for example, the human epidermis undergoes gradual tanning as a result of an increase in melanin pigment. human substantia nigra and locus ceruleus showed that neuro-melanin granules were located in the neuronal perikaryon and were surrounded by a double membrane  similar those of the cell membrane.
Jul 21, · The antimicrobial properties of melanocytes, melanosomes and melanin and the evolution of black skin. Mackintosh JA.
Erratum in J Theor Biol Sep 7;(1) A biological issue that has not been satisfactorily resolved is the role of melanin in skin and other animal tissues. The highest correlation between skin reflectance and UV levels was observed at nm, near the absorption maximum for oxyhemoglobin, suggesting that the main role of melanin pigmentation in humans is regulation of the effects of UV radiation on the contents of cutaneous blood vessels located in the dermis.
(2) Predicted skin reflectances . Essay Examples. search essay examples. browse by category argumentative. compare and contrast. log in × scroll to top. Melanin Essay Examples.
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