Lighter Skin In Europeans due to agriculture?

[kurite]

NEWS FOCUS
AMERICAN ASSOCIATION OF PHYSICAL ANTHROPOLOGISTS MEETING
European Skin Turned Pale Only Recently, Gene Suggests
Ann Gibbons
AMERICAN ASSOCIATION OF PHYSICAL ANTHROPOLOGISTS, 28-31 MARCH, PHILADELPHIA, PENNSYLVANIA
Researchers have disagreed for decades about an issue that is only skin-deep: How quickly did the first modern humans who swept into Europe acquire pale skin? Now a new report on the evolution of a gene for skin color suggests that Europeans lightened up quite recently, perhaps only 6000 to 12,000 years ago. This contradicts a long-standing hypothesis that modern humans in Europe grew paler about 40,000 years ago, as soon as they migrated into northern latitudes. Under darker skies, pale skin absorbs more sunlight than dark skin, allowing ultraviolet rays to produce more vitamin D for bone growth and calcium absorption. “The [evolution of] light skin occurred long after the arrival of modern humans in Europe,” molecular anthropologist Heather Norton of the University of Arizona, Tucson, said in her talk.

The genetic origin of the spectrum of human skin colors has been one of the big puzzles of biology. Researchers made a major breakthrough in 2005 by discovering a gene, SLC24A5, that apparently causes pale skin in many Europeans, but not in Asians. A team led by geneticist Keith Cheng of Pennsylvania State University (PSU) College of Medicine in Hershey found two variants of the gene that differed by just one amino acid. Nearly all Africans and East Asians had one allele, whereas 98% of the 120 Europeans they studied had the other (Science, 28 October 2005, p. 601).

Norton, who worked on the Cheng study as a graduate student, decided to find out when that mutation swept through Europeans. Working as a postdoc with geneticist Michael Hammer at the University of Arizona, she sequenced 9300 base pairs of DNA in the SLC24A5 gene in 41 Europeans, Africans, Asians, and American Indians.

Using variations in the gene that did not cause paling, she calculated the background mutation rate of SLC24A5 and thereby determined that 18,000 years had passed since the light-skin allele was fixed in Europeans. But the error margins were large, so she also analyzed variation in the DNA flanking the gene. She found that Europeans with the allele had a “striking lack of diversity” in this flanking DNA—a sign of very recent genetic change, because not enough time has passed for new mutations to arise. The data suggest that the selective sweep occurred 5300 to 6000 years ago, but given the imprecision of method, the real date could be as far back as 12,000 years ago, Norton said. She added that other, unknown, genes probably also cause paling in Europeans.

Either way, the implication is that our European ancestors were brown-skinned for tens of thousands of years—a suggestion made 30 years ago by Stanford University geneticist L. Luca Cavalli-Sforza. He argued that the early immigrants to Europe, who were hunter-gatherers, herders, and fishers, survived on ready-made sources of vitamin D in their diet. But when farming spread in the past 6000 years, he argued, Europeans had fewer sources of vitamin D in their food and needed to absorb more sunlight to produce the vitamin in their skin. Cultural factors such as heavier clothing might also have favored increased absorption of sunlight on the few exposed areas of skin, such as hands and faces, says paleoanthropologist Nina Jablonski of PSU in State College.

Such recent changes in skin color show that humans are still evolving, says molecular anthropologist Henry Harpending of the University of Utah, Salt Lake City: “We have all tacitly assumed for years that modern humans showed up 45,000 years ago and have not changed much since, while this and other work shows that we continue to change, often at a very fast rate.”




http://www.sciencemag.org/content/316/5823/364.1.full?sid=76c7fab5-a2ef-40d0-8a6c-6b3044895a6f

Alternative link: http://img46.imageshack.us/img46/4784/eurospaleonlyrecentlypu0.jpg

[laterade]

So. If I keep eating this much meat... do you think my children will be black? 
This might make me look like a joke at parent teacher conferences.....

[TylerDurden]

The above report is utter nonsense and extremely unscientific. For one thing, they mistakenly assume that 1 sole gene is responsible for paleness of skin, even though this is highly unlikely. Indeed this wikipedia page has a sentence or two debunking this absurd notion that 1 gene is reponsible:- " Skin color is a quantitative trait that varies continuously on a gradient from dark to light, as it is a polygenic trait, under the influence of several genes. Many of these genes have yet to be identified." taken from:-

http://en.wikipedia.org/wiki/White_people#Origins_of_light_skin

 .  Also, they fail to recognise that many Orientals have very pale skin too, especially Northern Orientals in China, for example.

This subject was discussed  ages ago, here, in another thread, and I recall referring to data which showed that red hair(which coincides routinely with pale skin) appeared at the very least 80,000 years ago.

http://mathildasanthropologyblog.wordpress.com/2008/04/13/red-hair-skin-pigmentation-and-the-mcr1-variants/
 I had also mentioned that the original apeman which preceded humans and more recent apemen like  the Neanderthals(who first appeared any hundreds of thousands of years ago) are thought to have had pale skin
http://www.nytimes.com/2003/08/19/science/why-humans-and-their-fur-parted-ways.html?sec=health&spon=&pagewanted=3
 http://news.nationalgeographic.com/news/2007/10/071025-Neandertals-Redheads.html
which would mean that pale skin in humans is up to  5 million years old or more. This makes perfect sense when one realises that, in the wild, there are certain monkey species which have bright pink skin etc. I am thinking of Japanese Macaques. Another point is that the notion linking vitamin D to paler skin is only 1 theory, there are more solid theories out there explaining the change, such as the sexual selection theory. Oh, and the Neanderthals are claimed by scientists as having red hair and pale skin, so the notion of paler skin only occurring in modern humans is really ridiculous as humans have been shown to have interbred with the Neanderthals ages before.


Anyway, the above points easily show, once again, that we haven't changed at all, really, since the Palaeolithic.

*Just remembered that chimpanzees have  pale skin under all that fur. So it seems more logical to assume that dark skin was a more recent mutation in hominids than pale skin.

[PaleoPhil]

This is interesting:

“Somali women have vitamin D deficiency to a greater extent than Swedish women.” (translated from Swedish, http://www.dn.se/nyheter/sverige/krav-pa-nya-kostrad)

While there is strong evidence for sexual selection playing an important role in evolution of hair and skin color (Color Vision Drove Primates To Develop Red Skin And Hair, Study Finds, ScienceDaily, May 25, 2007, http://www.sciencedaily.com/releases/2007/05/070524155313.htm), does the above finding suggest that vitamin D might be a significant factor in skin color evolution? Is there some other explanation than darker skin color for why darker-skinned women have higher levels of vitamin D deficiency in Sweden?

There seems to be vitamin D in animal brains and marrow (and I'll bet back/hump fat too). These foods are not commonly consumed today, but were more common in the ancient past, probably especially before many fat-depot-rich Stone Age megafauna went extinct, possibly in part due to overhunting. Since brains and marrow aren’t commonly regarded as foods in the modern West, no one has bothered to measure their vitamin D content, AFAIK, but there are hints that there is vitamin D in the fatty parts of animals:

“Growing evidence from a group of studies in both rats and mice indicates that vitamin D is involved in normal structural brain development, though it is not clear yet if that is the case in humans.2 Mice born to mothers that were deficient in vitamin D before and during pregnancy had longer, thinner brains, with enlarged ventricles (brain fluid canals).” http://www.dana.org/news/cerebrum/detail.aspx?id=20980

“Parts of the bone marrow which produce immune cells are receptive to vitamin D.” http://www.womens-health-symmetry.com/vitamin-d.html

Plus, since vitamin D is fat soluble, fats from fatty sources like brains, marrow and fatty fish assist in the absorption of vitamin D.

Perhaps more importantly, cereals like wheat deplete vitamin D (http://www.direct-ms.org/pdf/EvolutionPaleolithic/Cereal%20Sword.pdf). Thus, both the declining megafauna populations and the adoption of agriculture, particularly of wheat, could have contributed to declining vitamin D levels in Europeans. Some scientists believe that lighter skin may have helped offset overall decline in vitamin D levels.

A number of researchers … suggest that the northern latitudes permitted enough synthesis of vitamin D combined with food sources from hunting to keep populations healthy, and only when agriculture was adopted was there a need for lighter skin to maximize the synthesis of vitamin D. The theory suggests that the reduction of game meat, fish, and some plants from the diet resulted in skin turning white many thousands of years after settlement in Europe and Asia.[44][45] This theory is supported by a study into theSLC24A5 gene which found that the allelle associated with light skin in Europe may have originated as recently as 6,000–10,000 years ago[23] which is in line with the earliest evidence of farming.[46] http://en.wikipedia.org/wiki/Human_skin_color#Evolution_of_skin_color

Plus, vitamin D production apparently may also be obtained via the eyes (by stimulating the pituitary gland) and hair (http://dx.doi.org/10.1016/S0024-3205(96)00586-3, http://www.naturalnews.com/027531_the_flu_immune_system_health.html, http://www.easy-immune-health.com/vitamin-d-and-the-pituitary-gland.html, http://ajplegacy.physiology.org/content/127/3/552.extract, http://www.sikhiwiki.org/index.php/Uncut_Hair) in addition to the skin, albeit more indirectly, so lighter-colored eyes and hair theoretically may also have helped, though my guess would be that vitamin D would be a small factor in hair color, if any.

“(B)oth the interfollicular epidermis and the hair follicle appear to require the vitamin D receptor for normal differentiation” (http://www.ncbi.nlm.nih.gov/pubmed/11851870?dopt=Abstract).

While we humans get most of our sunlight vitamin D via the skin, it seems premature to assume that none of our hairy primate necessity of obtaining some from grooming hair remains.

In addition, the use of heavy clothing, which increased over time even in northerly latitudes (for example, H. erectus survived in northern latitudes without clothing and probably without fire, despite Richard Wrangham’s speculations), may have been a factor.

Plus, sexual selection doesn't appear to explain why blond hair tends to turn darker with age (http://en.wikipedia.org/wiki/Blond). There are anecdotal reports of eye color lightening after conversion to a raw Paleo/ancestral-type diet from a Standard Western Diet, as well as improved skin tanning and decreased susceptibility to sunburn, which is suggestive that there are dietary factors in eye color and skin health, if not skin color.

Also, nature phenomena tend to be complex, often with multiple underlying causes. This could explain why no single cause seems to answer all the questions. Current knowledge is poor in this area, but my guess is that future research will reveal more evidence supportive of dietary factors, in addition to the sexual selection factor.

[TylerDurden]

The dietary notions re pale skin colour are just laughable, really, given that Neanderthals, for example, were cited as having pale skin etc.. As for the sexual selection theory, it makes sense. For one thing, blonde hair is a neotenous  and a recessive trait, so that would explain why it is more prevalent in a person's youth than at an older age.

[Josh]

Still though Tyler, do we need to reject it outright?

Let's say light skin was around before agriculture to a greater or lesser extent.

If people suddenly needed more vitamin D in their diet, it might be an advantage to have lighter skin.

So there is some selective breeding which creates lighter skin, and also as the trait is also there it could be a candidate for epigenetic change?

[TylerDurden]

Still though Tyler, do we need to reject it outright?

Let's say light skin was around before agriculture to a greater or lesser extent.

If people suddenly needed more vitamin D in their diet, it might be an advantage to have lighter skin.

So there is some selective breeding which creates lighter skin, and also as the trait is also there it could be a candidate for epigenetic change?

  The trouble is that evolution does not happen this fast. Take the adaptation to dairy issue:- 75 percent of the world's population are lactose-intolerant, despite many millenia(15,000?) of humans consuming dairy products in most regions worldwide. As for epigenetics, it seems only to affect things like predisposition to asthma and the like. Changing eye-colour or skin-colour due to diet or changing climate would be too drastic a change to be likely to occur.

There are some obvious flaws involved. For example, many Eskimoes have very pale light skin, yet they have been consuming diets extremely rich in vitamin D for many millenia(6,000 years plus). That kind of debunks the notion. I've also seen the same lame theory re vitamin D etc. used to explain the occurrence of blue eyes in Northern climes, but, again, the Inuit are a perfect example showing the exact opposite. Well, that is those Inuit who haven't mixed in with Europeans, of course!

[Josh]

Evolution is not fast, but selective breeding is faster.

I thought epigenetic change could affect things like tallness by affecting the expression of certain genes and could happen fairly quickly?

Regarding the Eskimo's, they eat a lot of vit D in diet, but then they live in a dark cold place so maybe they sometimes need to get all they can.

AFAIK they have Asian ancestry if you go back, so possibly they have lightened in response to climate...but who know's at what point they refined their diet to the high point it was (before modern influence)

So I don't think it debunks this...it may be neutral, or maybe support it as it's complicated.

I'm just saying it's not necessarily as simple as a 'yes' or 'no'

[TylerDurden]

 Tallness is a far more flexible characteristic than skin-colour( for example,  malnourished children can be much shorter than otherwise by the time they reach puberty due to a lack of growth-hormones etc., whereas a malnourished person will never be lighter or darker in skin-colour  due to a starvation diet pre-puberty).


The Eskimoes are cited as having such a high access to vitamin-D-rich foods that they easily get enough vitamin D from their diet even in the 6 months of relative darkness each year. So it's a pretty solid case against the notion.As for their actual diet, they appear to have reached the Arctic c. 6,000 years ago or more, and they are deeply unlikely  to have survived on a diet other than the usual Arctic one of caribou/seal-blubber etc. within that Arctic environment, since agricultural foods and the like were wholly unavailable there.

Then there's the vitamin-d deficiency rickets which does not seem to either lighten or darken the skin, either.

So, the vitamin D notion is pretty much debunked.

The sexual selection theory has some good points such as the fact that the Japanese and Indian upper classes selected for paler skin as a trait, which is why they are paler than the rest of their societies.

[PaleoPhil]

 The trouble is that evolution does not happen this fast.

It's true that major evolutionary changes don't happen fast, but epigenetic changes can happen within a single individual's lifetime and F. Pottenger, Brent Pottenger, Stephan Guyenet, Loren Cordain, Ray Audette, anthropologists, explorers, WAP, WAPF (I know you don't put much stock in the last couple sources, but they are just two of many) and others have reported that a mere three generations or less of drastic dietary change can produce some surprisingly significant changes in humans and nonhuman animals.

As for epigenetics, it seems only to affect things like predisposition to asthma and the like.

"And the like" includes a lot of other things per the above sources.

Changing eye-colour ... due to diet or changing climate would be too drastic a change to be likely to occur.

Didn't you report that your eye color changed after a time on a raw Paleo diet (not even a single full generation)? If dietary change can have that sort of effect, it's not implausible to suspect that it might produce even greater effects over multiple generations.

There are some obvious flaws involved. For example, many Eskimoes have very pale light skin, yet they have been consuming diets extremely rich in vitamin D for many millenia(6,000 years plus). That kind of debunks the notion.

Not at all. The theory is that the dietary component of skin color lightening was due to a REDUCTION in vitamin D intake (not the reverse) plus an increase in grains and other agrarian foods which deplete vitamin D levels and that lighter skin provided an advantage in providing higher levels of vitamin D from the sun. The report on Ethiopian women in Sweden supports this. This adds to the evidence that Cordain and others already reported. As the evidence accumulates your position becomes less and less tenable.

One thing to keep in mind that you seem to frequently get confused about, is that the scientific consensus is not that ONLY diet plays a role in skin color change, but that it is one more potential factor in addition to sexual selection, latitude, climate, clothing, and other potential factors. I know of no scientist who claims that it HAS to be an either/or proposition. Science and nature rarely work that way. Yes, sexual selection appears to be an important factor, perhaps the single most important factor, but it has yet to explain everything and you seem to be practicing a "see-no-evil" cherry-picking approach where you consider some of the evidence, but ignore the rest. Whatever doesn't fit your preconceived notion appears to get discarded without serious consideration.

So, the vitamin D notion is pretty much debunked.

I happen to follow the blog of one of the most ardent promoters of the sexual selection hypothesis (so ardent as to be quite controversial) and even he does not make the extreme claim that vitamin D has been completely debunked.

[TylerDurden]

Didn't you report that your eye color changed after a time on a raw Paleo diet (not even a single full generation)? If dietary change can have that sort of effect, it's not implausible to suspect that it might produce even greater effects over multiple generations.

  Actually, the effect seems to be muted. That is, my eyes got a bit lighter in the outer half of my irises, but any change seems to have stalled permanently. Eye-colour does seems to be influenced more easily than skin-colour, I'll grant, given that various health-problems can change the colour in some ways. However, I have yet to see any remote evidence showing that Northern Europeans, who go rawpalaeo a year or more before having children, being then, supposedly,  more likely to produce children with light-coloured eyes.

Not at all. The theory is that the dietary component of skin color lightening was due to a REDUCTION in vitamin D intake (not the reverse) plus an increase in grains and other agrarian foods which deplete vitamin D levels and that lighter skin provided an advantage in providing higher levels of vitamin D from the sun. The report on Ethiopian women in Sweden supports this. This adds to the evidence that Cordain and others already reported. As the evidence accumulates your position becomes less and less tenable.

Well, the notion that skin-colour is linked to climate is pretty much destroyed by the example of the Asiatic Inuits, since they were there at least 6,000 years ago.

You are also overlooking a rather obvious fact. Most of the Inuit have been eating modern, processed agrarian diets filled with large amounts of grains for several generations now, but no skin-lightening or darkening in their populations has occurred as a result, even in those Inuit who have migrated to southern, warmer climes. That pretty much casts doubt on the notion. There are other problems with skin-colour changes:- for example, those European families living for centuries in colonial times(18th to 20th century), should, in theory, have gotten darker skin over  the generations of living in a much hotter climate, in order to cope with the extra UV rays there, but no such evidence exists. That makes me doubt any link to climate.

Also, the fact that Somali women(not Ethiopian, as I recall?) have vitamin d deficiency when in Sweden does not prove anything. The only way the vitamin D hypothesis could be proved is if these Ethiopian women or their descendants started developing lighter skin.

One thing to keep in mind that you seem to frequently get confused about, is that the scientific consensus is not that ONLY diet plays a role in skin color change, but that it is one more potential factor in addition to sexual selection, latitude, climate, clothing, and other potential factors. I know of no scientist who claims that it HAS to be an either/or proposition. Science and nature rarely work that way. Yes, sexual selection appears to be an important factor, perhaps the single most important factor, but it has yet to explain everything and you seem to be practicing a "see-no-evil" cherry-picking approach where you consider some of the evidence, but ignore the rest. Whatever doesn't fit your preconceived notion appears to get discarded without serious consideration.

Nonsense as usual. Ironically, many such articles that have been quoted re the vitamin-D theory have stated such absurdities/outright claims such as that white skin simply did not appear until a few thousand years ago. Given plentiful evidence to the contrary from the Neanderthals, and  the evidence that red hair(which coincides with pale skin) appeared at least 80,000 years ago and probably much earlier, the fact that it has been mentioned that skin-colour depends on a combination of different genes rather than just 1 or 2 genes and is not fully understood as yet etc., one can be reasonably sure that the vitamin D notion is highly unlikely as a theory.

I happen to follow the blog of one of the most ardent promoters of the sexual selection hypothesis (so ardent as to be quite controversial) and even he does not make the extreme claim that vitamin D has been completely debunked.

  Scientists usually don't try to claim that the opposing side is dead wrong even when the evidence piles up against it, as it can make them look bad, PR-wise. So they play safe, regardless of the actual evidence they know of. Meaningless, therefore.

[Josh]

If it was all due to sexual selection, why do all groups not become lighter then?

Why did the inuits become lighter than most Asians? They just happen to live somewhere that's dark and cold...

[TylerDurden]

If it was all due to sexual selection, why do all groups not become lighter then?

Why did the inuits become lighter than most Asians? They just happen to live somewhere that's dark and cold...

  The sexual selection theory only applies lightness of skin-colour to females. If, as is quite possible, there is a corresponding female bias for darker skin among males, that would explain why not all get lighter skin. Also, the sexual selection theory suggests that those in the upper-classes(cf India/Japan etc.) are the ones with the bias towards lighter skin(and the ability to obtain it re wealth), but since the upper-classes generally have fewer children than those further down, that might cancel things out somewhat due to a lower birth-rate.

There are also plenty of lighter-skinned Asians far further south in China and Japan, Malaysia, India and elsewhere, precisely because in those societies, having paler skin as a woman is considered a bonus. Then there are the yellow-haired Australian Aborigines - one would at least expect them to all have black hair since they have been so long  in such a hot climate.

[Josh]

One way of looking at it could be this:

There is a selection pressure to have dark skin in hot countries to protect from UV.

Once this pressure is lifted by moving to a cold climate, it enables the sexual selection for lighter skin to take priority.

This would explain your ruling classes, as they are also freed from outdoor activity..and also highly selectively bred.

So it is sexual selection, but you need the climate change to enable this to happen.

[TylerDurden]

Like I said, though, there have been many Northern European colonial families living for centuries in very hot countries, but they didn't develop darker skin as a protection against the sun. So the selection pressure to have darker skin would likely be nonexistent.

As for outdoor activity, actually, ruling classes are typical for being very active outdoors since they went in for constant hunting etc.

[Josh]

Well as I understand it melatonin does protect from UV..and it would seem strange to me if it was totally random that people are dark in Africa and Australia and lighter in cooler climates.

Maybe your colonial families are an argument against rapid epigenetic change, maybe it has to be evolution.

[TylerDurden]

Maybe your colonial families are an argument against rapid epigenetic change, maybe it has to be evolution.

  That's what I think. What I mean is, it might be possible for the Inuit, say, to have gotten more lighter-skinned when going into the Arctic, but the specific genes for white skin would have already been there in their gene-pool for millions of years past, not just suddenly appearing. After all, as I said before, our common apeman ancestor 5 million years ago, appears to have had pale skin.

[miles]

Yo brahs lemme ekshplain

In the case that sexual selection would favour fair skin and hair, it would not just be because people would have a fetish for it... Here's how it would go:

If a few hundred dark-skinned people move to Shweden, and no one else is there, their health will decrease from a lack of vitamin D. Some of these people may have lighter skin, or their skin may lose its melanin faster than the others in response to a lack of sunlight. These people will be healthier and therefore more attractive than the others. The sexual selection is still based on the attractiveness(health), but now the people with lighter skin happen to develop better and be healthier, and thus more attractive, which would in time become associated with the lighter skin/hair. It's not just because people randomly like the colour.. The people with darker skin would breed less and less and the light skinned more and more, and the groups would diverge with the light-skinned increasing in number and the dark-skinned decreasing.

[Josh]

Why do African societies etc also have a preference for lighter skin then, not just northen places?

[miles]

Why do African societies etc also have a preference for lighter skin then, not just northen places?

African societies who are modernising, working more indoors, wearing more clothes etc?

[TylerDurden]

Why on Earth would health be the same as beauty, of all things? Take foot-binding, for example, which was very unhealthy for Chinese women but which made them far more attractive/beautiful to their men.

[miles]

Why on Earth would health be the same as beauty, of all things? Take foot-binding, for example, which was very unhealthy for Chinese women but which made them far more attractive/beautiful to their men.

That's fucked up.

Foot binding is ugly and that's why it started. Because some Queen or something had a fucked up foot, so the King made every woman have fucked up feet so the Queen's foot wouldn't look so bad.

Health= Sexual Attractiveness. That's the lifetime health of your parents, the health of your Dad and Mum when you were conceived, your mum when she was pregnant, you when you were developing, you in the recent past and you now. The healthier you were through these periods put together, the more sexually attractive you will be.

[TylerDurden]

That's fucked up.

Foot binding is ugly and that's why it started. Because some Queen or something had a fucked up foot, so the King made every woman have fucked up feet so the Queen's foot wouldn't look so bad.

Health= Sexual Attractiveness. That's the lifetime health of your parents, the health of your Dad and Mum when you were conceived, your mum when she was pregnant, you when you were developing, you in the recent past and you now. The healthier you were through these periods put together, the more sexually attractive you will be.

Like I said, it's all a matter of perception. Some people who are unhealthy, such as those who've had plastic surgery of some sort etc., may well look more beautiful than someone actually more healthy but seemingly plainer.

As regards foot-binding there seem to be a number of theories re its use. 1 seems to be that it was a sign that the husband was so rich that he could afford to have a wife who did no manual labour in the fields. So that made her more attractive in his eyes, and so on:-

http://en.wikipedia.org/wiki/Foot_binding

[Josh]

"Although virtually all cultures express a marked preference for fair female skin, even those with little or no exposure to European imperialism, and even those whose members are heavily pigmented, many are indifferent to male pigmentation or even prefer men to be darker."

I remember reading this some time ago on wikipedia. It seems to be just one of those things.

http://en.wikipedia.org/wiki/Human_skin_color#Cultural_aspects_of_skin_color

[PaleoPhil]

Tyler, I'm not saying that any of the proposed hypotheses are "proven" (all that I know is that I know nothing for certain). I'm just asking questions, such as is it really safe to rule out the hypotheses re: vitamin D intake, diet and sunlight/climate, as these remarks of yours seem to suggest we should (please correct me if I misunderstand)?:

> the hypothesis of geneticist Keith Cheng, Cavalli-Sforza, Cordain et al "that Europeans lightened up quite recently, perhaps only 6000 to 12,000 years ago" is "utter nonsense"
> "the original apemen which preceded humans and more recent apemen like  the Neanderthals(who first appeared any hundreds of thousands of years ago) are thought to have had pale skin"
> "the notion that skin-colour is linked to climate is pretty much destroyed"
> data show that "red hair(which coincides routinely with pale skin) appeared at the very least 80,000 years ago"
> "The dietary notions re pale skin colour are just laughable"

If vitamin D intake, diet and sunlight can be ruled out, then there would presumably be at least one other factor that would explain why Somali women in Sweden have reportedly lower levels of vitamin D than Swedish women, yes? Do you have one to propose?

it might be possible for the Inuit, say, to have gotten more lighter-skinned when going into the Arctic.

Might be possible? Are you saying that their ancestors were probably all just as light-skinned, going all the way back to the first hominid?