Where does white skin come from? asks New Scientist, 22 August 2009, p10. White skin is believed to have developed when newly evolved humans, who were dark-skinned, moved out of sunny Africa and migrated to northerly regions of Europe where they did not get enough sun to make vitamin D. Vitamin D deficiency causes rickets – a bone deforming disease that would be selected against in the struggle for life.
This belief is now being questioned by Ashley Robins of the University of Cape Town Medical School, South Africa. Dark skinned people in high latitudes need six to ten times as much sun exposure than light skinned people to make sufficient vitamin D, but this only equates to two to three hours of sunlight three times a week. Robins commented: “Early humans would have had that amount of exposure every day, and that would certainly have overwritten any melanin (skin pigment) barrier. I’m pretty certain that you would not have got vitamin D deficiency and rickets.”
Robins also points to a recent study of vitamin D in black and white human volunteers. Following exposure to the same amount of light the black subjects had less Vitamin D in their blood, but they had almost the same amount of vitamin D metabolites, i.e. chemicals made within the body using vitamin D. This indicates the liver and kidneys are working more efficiently – i.e. are compensating for the lower levels. Robins commented: “There seems to be a compensatory mechanism. That’s another reason why the vitamin D hypothesis fails.”
Another group of scientists led by Asta Juzeniene, of the Oslo University Hospital have reviewed alternative theories for white skin. These included sexual selection for lighter skin and increased proneness to frostbite in dark skinned people. However, Juzeniene commented: “The vitamin D hypothesis is the most likely hypothesis although there is still no consensus about it.” Robins thinks the frostbite theory could be right. He commented: “If darker skin people are going to have frostbite, and babies and mothers’ nipples are going to be frostbitten, then like sunburn, this is going to be a potent selective force.”
Editorial Comment: Robins is right about most people being able to get enough sunlight. It is only since the Industrial revolution that people in northern regions have been forced to spend their lives inside, without any exposure to sunlight.
The distribution of skin colour over the world is hard to explain in purely evolutionary terms, but does fit with the Biblical description of human dispersion after Noah’s flood and the Tower of Babel. Two of Noah’s sons had names that indicated their colouring. Ham means “dark” and Japheth means “fair” or “light”, i.e. their skin colour came suddenly and was noted in their names by their parents. This probably occurred in the same way that brown parents today can have identical twins where one is black and the other white and separation at adulthood will produce separate coloured families right away – no evolution at all.
The Bible records that after the judgement at the Tower of Babel many of the descendants of fair skinned Japheth moved north and west into the regions that now comprise Europe. Ham’s dark descendants mainly went south into Africa. After the dispersion, people were split up into small clan groups that initially only bred within themselves, which would have reinforced the already existing predominant skin colour. (Ref. anthropology, pigmentation, nutrition)
Evidence News, 2 September 2009