Quote:
Originally Posted by Meg_S
Do you have any links for that Northern European genetic stuff? I'm pretty interested in reading about it. I had always thought that the more fair you were, the easier it was to get enough on smaller amounts of sun exposure and was feeling pretty safe...but with German, Norway and Scotland in my background I'm not so sure.
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I can never refind the exact article when I want. To paraphrase: As peoples moved north there were selections for genetic mutations for lighter skin which allowed for vitamin D synthesis under less strong sun. The further north people moved, the lighter the skin got. However, there came a time and place in the furthest north reaches where sun could not produce vitamin D most of the year even though the people got really, really pale. These peoples ate fish that was rich in vitamin D and so provided for D needs that way. So they survived. The fact that they were getting vitamin D from the sea and not from the sun allowed them to survive their environment with the result that over generations they reduced the number of vitamin D receptors in the skin (probably also due to the continual need for clothing due to the harsher environment). The lost receptors led to the inability to produce enough vitamin D from the sun, and a loss of the ability to tan (related to vitamin D synthesis and sun protection).
Thus lighter skin is a benefit to vitamin D synthesis until it is too light (of Northern European/Scandinavian heritage) at which point vitamin D synthesis is impaired and this impairedness(?) was passed along in the genes to suceeding generations.
This is why Northern European/Scandinavians and Blacks have correlating rates of cancers and high blood pressure. It's also why Scandinavian countries have higher incidences of MS, fibromyalgia, and CFS.
Interestingly, until the 70s, most Scandinavian countries mandated that children and pregnant women be given 2,000 IU/Day of vitamin D. Their rates of Diabetes Type I were much lower. Prenatal vitamin D deficiency has been linked to autism and schizophrenia.
These aren't the exact article I was searching for but give you the gist.
http://www.derm.med.ed.ac.uk/PDF/Am...on%202004 .pdf
The Genetics of Sun Sensitivity in Humans
Jonathan L. Rees
Systems Group, Dermatology, University of Edinburgh, Edinburgh
http://www.fao.org/docrep/W7336T/w7336t03.htm
The roles of calcium and vitamin D in skeletal health: an evolutionary perspective
http://www.derm.med.ed.ac.uk/PDF/Ge...in%20Colour.pdf
GENETICS OF HAIR AND SKIN COLOR
Jonathan L. Rees
Systems Group, Dermatology, University of Edinburgh, Lauriston Buildings, Lauriston
Place, Edinburgh, EH3 9YW, United Kingdom; email: jrees~staffmail.ed.ac.uk