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Female/Male skin colour difference almost insignificant
Why does it say in the article, in chapter 4, "...females are considerably lighter in skin pigmentation than males" when the difference is actually very small, at only 3-5% at most? That's hardly considerably lighter. Lol!
It is a remnant of discussion of an alternative proposed explanation for geographical skin colour variation that centres on marriage practices instead of vitamin D., which got completely removed. The "Vitamin D" explanation is not theory it's only a hypothesis, and has some evidence casting doubt on it. A large scale association study of the genetic determinants of vitamin D insufficiency in Caucasians found no links to pigmentation. Reference "Common genetic determinants of vitamin D insufficiency: a genome-wide association study". Lancet376 (9736): 180–8. 2010. doi:10.1016/S0140-6736(10)60588-0. PMC3086761. PMID20541252.. But all mention of alternative hypotheses has been deleted, and the article states without qualification in the lede that it is UV penetration. No other hypothesis is mentioned but the UVb and vitamin D synthesis one, which would lead any reasonable person to believe that vitamin D supplements are required for dark skinned people to be healthy while living at high latitude, which the Institute of Medicine of the National Academies has found not to be the case. In fact they found taking vitamin D supplements was not only unnecessary for African Americans but tended to harm their health. "Additionally, a cross-sectional study conducted by Freedman et al. (2010) reported a positive association between serum 25OHD level and calcified atherosclerotic plaque in the aorta and carotid arteries of African Americans and and preliminary reports from NHANES suggest that the risk for all-cause mortality among non-Hispanic blacks compared with whites occurs at a lower serum 25OHD level (60 vs. 75 nmol/L)." Here. Harm from vitamin D appears to occur at a lower vitamin D level in the black population than in the white population. Reference Dietary Reference Intakes for Calcium and Vitamin D. Washington, D.C: National Academies Press. 2011. ISBN0-309-16394-3.. Development of different human skin colors: a review highlighting photobiological and photobiophysical aspects says " Hypotheses for skin lightening are: sexual selection, adaptation to cold climates, enhancement of vitamin D photoproduction, and changing food habits leading to lower intake of vitamin D." To answer your question, because those editing this Wikipedia article have enforced one hypothesis, and deleted the others.Overagainst (talk) 17:03, 28 July 2014 (UTC)