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However, in light skinned populations, namely those of European descent, women have darker skin than men. [11] [110] It is unknown why skin color is sexually dimorphic in some populations. White women may have darker skin than white men because the female sex hormone estrogen is known to increase skin pigmentation in lighter-skinned populations ...
The same ultraviolet radiation is essential for the synthesis of vitamin D in skin, so lighter colored skin – less melanin – is an adaptation related to the prehistoric movement of humans away from equatorial regions, as there is less exposure to sunlight at higher latitudes.
Total melanin content in the epidermis ranges from around 0 μg/mg in albino epidermal tissue [8] to >10 μg/mg in darker tissue. [9] In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV ...
It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin. [2] Some common genetic causes include mutations in the tyrosinase gene or OCA2 gene. [3] [4] As melanin pigments tend to be in the skin, eye, and hair, these are the commonly affected areas in those with ...
Amelanistic mammals have white hair, pink skin, and eyes that have a pink, red, or violet appearance. Reddish eyes are due to the lack of pigment in the iris pigment epithelium. When the stroma is unpigmented but the iris pigment epithelium is not, mammalian eyes appear blue. Melanin in the pigment epithelium is critical for visual acuity and ...
Furthermore, these people have been living in the far north for less than 7,000 years. As their founding populations lacked alleles for light skin colour, they may have had insufficient time for significantly lower melanin production to have been selected for by nature after being introduced by random mutations. [65] "This was one of the last ...
Melanin is a class of pigment responsible for producing color in the body in places such as the eyes, skin, and hair. The process of melanin synthesis (melanogenesis) starts with the oxidation of l -tyrosine to l-dopa by the enzyme tyrosine hydroxylase , then to l -dopaquinone and dopachrome , which forms melanin.
Depigmentation is the lightening of the skin or loss of pigment. Depigmentation of the skin can be caused by a number of local and systemic conditions. The pigment loss can be partial (injury to the skin) or complete (caused by vitiligo).