>>11116567There's a gene called KITLG - stem cell-something-something-factor-something.
Stem cells can either multiply, or differentiate. If they differentiate, they aren't stem cells anymore. Our genes program these stem cells in such a way that each generation, fewer undifferentiated stem cells exist.
All other races live longer, healthier lifes than blacks because the same genes that control stem cell differentiation are involved in pigmentation.
Basically, babies have less melanin. One of the reasons is that these genes that promote stem cell proliferation and downregulate the developmental cytokines that cause melanocyte maturation.
Pale, rosy skin is caused by the presence of small quantities of pheomelanin and low or no quantities of eumelanin. Black or brown skin is caused by ample eumelanin.
In the body, pheomelanin is synthesized by the melanin pathway when sulfur is present in the form of cysteine or glutathione, which are consumed in the process of making pheomelanin.
When cysteine/glutathione is depleted, pheomelanogenesis becomes impossible and eumelanin is solely produced. This could be why people with blond or red hair go dark with age.
Supplementing the diet with cysteine (Which is converted to glutathione in the body - glutathione is an antioxidant) could hypothetically cause pheomelanogenesis to be favored, but the cysteine would likely be quickly depleted - which is why you have dark hair in the first place.
Uva ursi, containing arbutin, functions as a competitive substrate for L-dopa and has melanogenesis-inhibiting properties because arbutin is metabolized in part into hydroquinone. Arbutin could reduce the rate of melanogenesis to a level where cysteine isn't used up, and all melanin is pheomelanin.
In animal models, animals with derived pigmentation genes that lower melanogenesis respond more potently to this regimen than animals with ancestral dark pigmentation.
