Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Kevan Gelling on 02/07/2009 21:59:02
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In the recent podcast on 24th May 2009 called "Getting Under Your Skin", there was an interview with Professor Nina Jablonski, an anthropologist at Penn State University. During the course of the interview, Professor Jablonski stated "The reason that your ancestors underwent loss of pigmentation is that you still need to make vitamin-D in your skin."
If this theory is true (and I think it holds more water than the theory that loss of pigmentation was because it wasn't needed) then they are implications on how we think about vitamin D3.
Having less pigmentation isn't without a cost - there at least three disadvantages:
- Skin cancer - This occurs at all latitudes and, as Dr Chris noted in his question, why not keep the pigmentation and, hey presto, no skin cancer
- Premature Skin Aging - UVA rays damages skin and makes it look old. This makes a person less attractive to the opposite sex and effectively reduces their reproduction lifespan.
- You look different - The evidence is that homo sapiens succeeded because they co-operated (according to Dr Roberts (http://www.bbc.co.uk/programmes/b00klf6j)). Humans do not empathise as well with humans who have significant racial differences and this appears to be hard-wired (from New Scientist (http://www.newscientist.com/article/dn17399-brains-response-muted-when-we-see-other-races-in-pain.html)).
In a cut-throat Darwinian world each of these, on their own, would be a serious disadvantage; when combined the only conclusion must be that the up-side, of vitamin D3 production, must be significant.
It is accepted that not enough vitamin D is a cause of rickets. But rickets can be prevented with the correct diet (eggs, liver, milk, mushrooms). If this was the only downside of low levels of vitamin D3 then why didn't we evolve a penchant for food with vitamin D in it (in the same way that we find cooked meat and salt appealing) and kept the benefits of pigmentation?
There must be something else about making vitamin D3 from sunlight in our skin that is of considerable important to our wellbeing.
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Eggs, liver, milk and mushrooms? Our ancestors hundreds of thousands of years ago probably didn't farm chickens for eggs, or cows for milk, and a lot of mushrooms tend to be poisonous so probably avoided those. I guess that leaves livers, but sunlight was probably a hell of a lot more abundant than livers.
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Vitamin D3 is fat soluble. I wonder if a D3 deficiency makes one crave fat. It could explain the Scots' apparent poor diet, for example.