Anil Ananthaswamy, New Scientist, August 19, 2009
THE idea that early humans became fair-skinned as they migrated north out of Africa so they could make enough vitamin D to stay healthy has been questioned again, reopening a debate that many think is settled.
In equatorial Africa and in the tropics, melanin—the pigment that makes skin dark—provides protection against the intense sunlight. But melanin can also block the ultraviolet radiation (UVB) that triggers vitamin D production in the skin. This is an advantage in the tropics, where UVB radiation is barely filtered by the atmosphere above.
But UVB intensity falls dramatically at higher latitudes, where melanin can pose a problem for dark-skinned people. Vitamin D deficiency can lead to rickets and women with the disease often develop a deformed pelvis, making it difficult for them to reproduce.
According to the vitamin D hypothesis, when humans left Africa tens of thousands of years ago and reached Europe, natural selection weeded out the melanin. While people with lighter skin could produce adequate levels of vitamin D, those whose skin remained dark were more likely to suffer from rickets. The hypothesis arose when studies from the early 20th century showed that blacks in the US were two to three times as likely to suffer from the disease as whites.
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Robins [Ashley Robins of the University of Cape Town Medical School, Observatory, South Africa] is one of the few, arguing that adequate vitamin D wouldn’t necessarily have been a problem. Melanin is not an absolute screen against UVB, he says. Dark-skinned people in higher latitudes need to be exposed to about 6 to 10 times as much sunlight as white-skinned people for the vitamin D in their blood to reach acceptable levels. This equates to about 2 to 3 hours of sunlight about 3 times a week for Africans living in, say, the UK. “Early humans would have had that amount of exposure every day,” says Robins. {snip}
Robins also points to studies showing that while black volunteers have significantly lower blood levels of vitamin D than white volunteers after a whole-body dose of UVB, the difference narrowed and even disappeared when levels of metabolites derived from vitamin D were compared (American Journal of Physical Anthropology, DOI: 10.1002/ajpa.21077). This suggests that in darker-skinned people, enzymes from the liver and kidneys were working harder to keep the levels of the active metabolites the same, regardless of the skin pigmentation. “There seems to be a compensatory mechanism,” says Robins. “That’s another reason why the vitamin D hypothesis fails.”
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Juzeniene [Asta Juzeniene, of the Oslo University Hospital in Montebello, Norway] and her colleagues recently reviewed alternate hypotheses for why humans might have evolved lighter skin (Journal of Photochemistry and Photobiology B: Biology, vol 96, p 93). One highly controversial idea involves sexual selection: once sensitive light skin was no longer hazardous, as in Africa, it was selected for sexual attractiveness. The other idea is that dark skin was more prone to frostbite in higher latitudes, and hence would have come under negative selection pressure, a claim that comes from studies of soldiers during the Korean war, when black soldiers suffered far more frostbite than white soldiers.
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Original article
(Posted on August 25, 2009)
Comments
One highly controversial idea involves sexual selection: once sensitive light skin was no longer hazardous, as in Africa, it was selected for sexual attractiveness.
Why should it be “controversial” at all? It’s true: “White Is Beautiful.” In just about every non-white culture, including black African, lighter skin is thought more attractive, and was thought to be so long before contact with white people.
What a crock.
First, the Out of Africa story is nothing more than a politically correct myth. It has never been proved. It is a theory only.
Second, only 50 years ago black supremacists and their white enablers were claiming that Whites were the most primitive of humans because our skin is white. Look at animals said the anti White racists. Their skin is white because the fur and hair cover it. Therefore Whites are the nearest to animals and the last humans to evolve. Blacks were supposed to be the earliest to evolve from hairy animals, tan and gold skinned asians evolved next and then Whites.
Third, even if modern humans did originate in Africa, there is no reason to believe that their skin was black.
This theory totally ignores some important facts of human anatomy. Blacks have much less need of vitamin D and calcium because their bones are much denser than the bones of Whites and Asians.
Whites and Asians need vitamin D and calcium to prevent their bones from crumbling. Blacks have little need for vitamin D.
Blacks only get rickets from fairly severe malnutrition. In the 19th and early 20th century many southern black and White children got rickets from severe malnutrition.
But blacks don’t get rickets from lack of sunlight, vitamin D and calcium because their bones are so dense and solid.
More ignorant blathering and blithering from the idiot pundits.
Sorry but why should all people originate from Africa?
Research carried out by L.L. Cavalli-Sforza and two2.288 genetic point difference . The research foundthe English differ from the Danes, Germans and of genetic distance,
They might’ve spent a bloody word or two explaining WHY blacks are so much more prone to frostbite. I’d surely like to know, anyway.
Maybe something to do with blood flow? Say, whites have more capillaries? Going by what I read, blacks have thicker skin.
It’s hard to see how white skin in itself would protect you from frostbite. So if blacks are more susceptible to frostbite it is probably due to some more general sort of cold tolerance in white people’s skin that’s independent of the pigmentation.
Sexual selection may well have something to do with the evolution of white skin. Even blacks seem to prefer lighter skinned women, whether they are black women who can pass the paper bag test, or women who are simply white. The preference for lighter skin also is found in India and China.
The Russian Fox experiment showed that selecting for a single behavioural trait (tameness) could lead to a number of other changes including changes in fur colour, changes in skull shape, decreased adrenal production and increased serotonin making them more docile & domesticated.
If groups were geographically separated and different selection pressures applied (for instance, groups which developed agriculture experienced population growth, this would increase the potential for mutations to occur, land became scarce; agriculture became more labor intensive; and men had to provide for their families). Miller has written about this here:
“Climate has been the most common source for differential selection for intelligence. These theories have argued that the intellectual demands of life in cold climates was greater than in warm climates. Lynn (1991b) has placed emphasis on the intellectual abilities needed to survive cold, to build fires, and to hunt in groups. Rushton (1995) has presented a theory involving r versus K selection. Miller (1991) has pointed to the need to store food to survive the winter and how this may have selected for intelligence. He has also (Miller, 1995) argued that one of the advantages of intelligence was that it helped in detecting deception in mates and potential mates, and that this ability was more important in cold climates than in warm ones. The implicit assumption in these models is that the same alleles were present in virtually all populations. Thus, intellectual differences between populations must reflect differences in the strength of selection for intelligence. The alternative to be presented here is that some populations were reached more quickly by more of the mutations that produce high intelligence. These became the more intelligent populations. Other populations, those that were less accessible to intelligence increasing mutations, lagged in intelligence. Thus, the populations reached by the largest numbers of such mutations would have the highest average intelligence. Most populations experienced selection for intelligence, although its strength may have differed.”
http://www.lrainc.com/swtaboo/stalkers/em_geocn.html
Having soldiered beside blacks in arctic conditions in Canada, I would venture an unscientific theory that black soldiers may not have been taking the same precautions and effective preventive measures against frostbite as their white colleagues.
Surviving and operating in a sub-zero environment tests a persons strengths in discipline, planning, and endurance.
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So now that you’ve “explained” how our skin got whiter, please tell us how our facial features got prettier.
Post # 9 - the propensity for blacks to suffer frostbite at a higher rate than whites isn’t due to not taking the same precautions. While stationed in Okinawa years ago, while in the Marines, everyone had to take turns pulling guard duty in the freezing cold. The blacks were told point blank to take in more fluid than the whites (and the few Asians) because they would become dehydrated much, much faster in the cold. A few blacks would ignore this here and there and some of them would actually pass out. Not fall asleep, pass out. Just as blacks are geared for heat, Caucasians and Asians are geared for handling the cold. I would also add that it’s easier to get acclimated to extreme heat etc than it is to get ‘used to’ the cold. Very different physiological processes at work. The whites had no problem in getting used to severe heat after a few days or weeks, but the blacks did have trouble in the cold no matter how long they lived in it.
I already knew the answer, but MC (#8) beat me to the punch!
There is a lot of evidence that somewhere in the Caucuses, a pre-historic tribe of people began to selectively breed themselves for intelligence, strength & daring. The white skin, blue eyes and fair hair were, like the Russian fox experiment MC cites, simply by-products.
The evidence includes the facts that 1) white characteristics are regressive, so it would be hard for them to arise naturally, 2) Historically, only whites “invented” selective breeding for animals and crops, 3) Up until the last century, whites instinctively accepted the idea of “nobles” who were superior because of their “breeding.” Even today, whites say someone is “well-bred” and believe that a person from a “good family” is better than someone whose family is trash.
I did not make this up by myself. Check out “March of the Titans: A History of the White Race, Vol 1” by Arthur Kemp. (c) 1999. Ostara Publications. ISBN 0-620-25117-4
Good luck finding it today!
MC, you’ve got some great points there. And how about simple selection for ‘tameness’ in populations who survived the last Ice Age? You’d have to be pretty darn tame to survive the cramped living conditions of that age. If you weren’t tame, you would not live through the long Ice Age winter, holed-up in some cave, or a hole dug in the ground (which was still a common arrangement for Central European peasantry, well into the Middle Ages), along with a bunch of severely-depressed and half-starved kinsmen. If you weren’t really level-headed, you’d have been killed. A feud, actually, could easily have resulted in the death of the entire extended family.
So maybe our coloring came as a result of selection for tameness (or altruism, or efficient brain metabolism, or intelligence, as you’ve suggested): precisely as happened with the Foxes, whose coloring also arose from selection for tameness. I have noticed that Scandinavians, who have the best coloring, also have the best dispositions.
My family, long ago, learned to sit next to blond families in restaurants. Blonds, almost invariably, are the quietest and best-behaved. There is no doubt, for me, that coloring and personality are linked.
I tend to believe the sumerian text and writings of zachariah sitchen. The original cavemen who were probably black in appearance,hunters, all of a sudden,began to know the ways of farming,astrology,weapons,ect,were infiltrated by intelligent beings called the annanuki. Dna was mixed and from these beings came the white race. Think this is far out? At least keep an open mind and read some of zecharia sitchins work.
“The other idea is that dark skin was more prone to frostbite in higher latitudes, and hence would have come under negative selection pressure, a claim that comes from studies of soldiers during the Korean war, when black soldiers suffered far more frostbite than white soldiers.”
The way it is stated - - is that troops from the “southern states” were seven times more susceptible to frostbite than are troops from “northern states”. But what about Eskimos then? Live even further north than even Scandanavians and yet they escape the susceptibility to frostbite? Troops from “southern states” were “predominantly” black?
Chimps when babies have very lite colored skin. Almost like a white person! ONLY gets darker when the adults age.
Paul, March of the Titans: A History of the White Race Vol 1 and 2 is available at http://www.white-history.com/index.htm
Clearly, from GOD.
The word, ‘adam’ in the Hebrew of the Old Testament, means (as per Strong’s concordance’ - ‘fair, ruddy, able to show red in the face.’
This is a distinctly unique characteristic of Whites alone. Adam was white. Europe knew this, and Christendom’s boundaries stopped where Europe’s stopped, until the rise of Enlightenment thinking, following on the heels of the Protestant Reformation.
As to where the other races come from, you can’t make a multicultural case from a book that was so racially exclusive, as to keep genealogies, even up to, and including Christ! [cf. Matthew, Chap 1] And, if the ‘first Adam’ was White, so, too, then, must the “Second Adam”. Christendom forgets this at her peril.
I find to hard to believe that white skin may have also evolved as a result of sexual preference if we all allegedly started off black-skinned and it was higher latitude environmental conditions outsde the Afrcan continent that were responsible for the gradual change in skin tones. Either lighter skin evolved as a result of sexual preference or it evolved as a consequence of opposite envionmental conditions. It can’t have been as a result of both.
If, according to the Out-of-Africa theorists, during the time span of the various migration episodes to the Far North of the globe, skin would have inevitably been growing lighter anyway so sexual preferences wouldn’t have entered into the equation.
Incidently, in China, Chinese educationalists do not hold with the OOA theory either.
I have sometimes wondered whether white skin was more useful to people living in close proximity with each other. Emotions such as anger and embarrassment show up as a flushed face in white people. This could help defuse situations before they arise by giving an early warning to how the other person is feeling. Just a thought.
Whites are not indigenous to this planet as are the other races who all possess black hair and eyes. Our race came from the stars and this explains our compulsion to return to space in rockets. This also explains why we have advanced light years beyond the dark skinned peoples…
Darwin’s theory is nonsense. If God made man in his image Darwin implies that God was a monkey. Darwin was a known atheist who believed in nothing beyond his own theories. Whites could no sooner evolve from blacks than elephants could evolve from spiders…
Darwin was a known atheist who believed in nothing beyond his own theories. Whites could no sooner evolve from blacks than elephants could evolve from spiders…
#24 Anonymous, I have to agree with you. I doubt highly, that whites evoloved from blacks, ala, Darwinian evolution. The races were probably created seperately, due to genetic manipulation by some agency outside of mere time and chance. The ancient Babylonian records state that people were created in the “House of Fashioning”, from more primitive humanoids. True or not, no one knows, but evolutionary processes seems too far out considering modern human beings have been on the earth for a relatively short period of time.
