Some Problems With Sexual Selection As The Sole Factor:
Why is there a dramatic increase in paleness in a concentrated area around 6,000 - 12,000 years ago? Was there a sexual/social revolution?
Short answer, there wasn't a dramatic increase in paleness, only the appearance of 1 minor gene. As pointed out in a previous article, the genes for red hair(which go hand in hand with paleness of skin in humans) originated much earlier, and the author makes it clear, based on that and other scientific evidence, that the skin of the Cro-Magnon whio existed well before 12,000 years ago, was just as pale as modern Caucasians:-
http://mathildasanthropologyblog.wordpress.com/2008/04/13/red-hair-skin-pigmentation-and-the-mcr1-variants/Why did blondness only arise in one small area of Aboriginal Australia instead of across its entirety and diffusely across the globe?
Actually, if you check the data, something like 90% of central Western Aboriginal Australians have blond hair as infants(turning to brown in adulthood):-
"especially in the west-central parts of the continent, have a high frequency of natural blond-to-brown hair,[22][23] with as many as 90-100% of children having blond hair in some areas"
derived from:- http://www.gnxp.com/blog/2005/08/blonde-australian-aboriginals.php
The article also mentions that the blond Aboriginal phenomenon appears on the southwest coast as well as the centre of the Continent and up North to Arnhem land. It is absent in eastern Australia , but that's easy to explain, as Australia isn't exactly easy to cross, given deserts etc. Plus, Australian Aborigines have been largely geographically isolated for c.40,000 years from the rest of the world.
Actually, there are similiar examples of this "blond nonwhite" phenomenon as it also " found in some other parts of the South Pacific such as the Solomon Islands Vanuatu and Fiji":-
http://en.wikipedia.org/wiki/BlondGiven that blondness is found among Pacific Islanders weren't able to interbreed with the Aborigines until very recently, due to geographical isolation, one can safely conclude that that particular gene for blond (nonwhite) hair appeared AT LEAST 40,000 years ago when the Australian Aborigines split from the rest of Southeast Asia and the Pacific, and most likely far, far before that date.
Why did the alleged sexual selection of the most intensely pale, blond/red haired blue/green eyed people only take place in one small region of the world, and not among numerous populations around the globe?
Well, there is widespread speculation, actually, where Northern Europeans came from. Some claim Siberia, others the Caucasus, no one really knows. Similiarly, red hair is spread throughout the world, not just the fringes of Western Europe, such as the Udmurt People of Asia, implying a more widespread origin than just Western Europe.Also, you are making a completely false assumption, that a particular genetic mutation should eventually appear worldwide. The whole point of different genes is that they offer different advantages, so one type of gene might predominate in 1 area due to a particular advantage( greater stamina or greater physical attractiveness, say), while the population of another region might prefer another kind of mutation, due to a preference for some other advantage( increased longevity, say)(not necessarily related to climate).
If red hair and pale skin arose due to a sexual preference, why did three studies find that red hair was seen as a negative for attractiveness and other criterion, and actually rated dead last among all the compared basic appearance types in one study? (http://www.eric.ed.gov/ERICWebPortal/custom/portlets/recordDetails/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=ED136161&ERICExtSearch_SearchType_0=no&accno=ED136161)
Those studies are heavily flawed. For one thing, as pointed out in wikipedia,
"Some have speculated that the dislike of red-hair may derive from the historical English sentiment that people of Irish or Celtic background, with a greater prevalence of red hair, were ethnically inferior.:-
http://news.bbc.co.uk/1/hi/magazine/6725653.stmWhat I find interesting is that the childish anti-ginger prejudice/gingerism(mostly against redheaired males) is only really found in the UK. Red-haired acquaintances of mine have stated that they don't get this sort of prejudice elsewhere in the world. Indeed, in many other areas like Malta, red hair is actually prized along with blond(no doubt due to rarity).
Another simpler explanation for modern prejudice re red hair:-
"Workplace psychologist Professor Cary Cooper, of Lancaster University, says abuse can be "an unhealthy release valve for stress" and redheads, as a visible minority not protected by law, have become a target.
While other forms of the discrimination are the subject of marches, lobbying and education campaigns, redheads cannot expect the arrival of the politically correct cavalry anytime soon."
Who knows there could be other possibilities. As mentioned in the article, red hair is seen as the colour of the devil, the colour of blood, and so is feared by some. Perhaps we got red hair from interbreeding with Neanderthals and so it's due to an ingrained racial bias against Neanderthals - though that's less likely than the other notions.
And, of course, studies on personal attractiveness are inevitably going to be loaded with bias due to ingrained notions and behavioural/cultural imprinting etc.. I think there was 1 study, mentioned somewhere or other, which tested babies' responses to photos of attractive women around the world and brown-haired women were rated at the top. Can't find the study, no matter but studies of this sort should be done on infants who haven't been influenced culturally.
And please don't anyone respond with something inane like "I prefer red heads." I'm readheaded myself, so I thank you , but that means nothing scientifically.
Not that it matters, but I do prefer them. Incidentally,if you are indeed red-haired, isn't claiming that red hair is a negative trait, therefore a form of self-hatred? Besides, red hair is pretty widespread, these days, so it has to have some advantage.
Because pale skin and red hair are perceived as feminine (see Exploring Male and Female Perceptions, http://pages.globetrotter.net/peter_frost61z/fwdm4.htm) and less unattractive on women, it's less of a problem for them, but it's still a minus overall for sexual selection.
Actually, red hair is seen as a rather savage, masculine trait:-
"Red hair was thought to be a mark of a beastly sexual desire and moral degeneration. A savage red-haired man is portrayed in the fable by Grimm brothers (Der Eisenhans) as the spirit of the forest of iron. Theophilus Presbyter describes how the blood of a red-haired young man is necessary to create gold from copper, in a mixture with the ashes of a basilisk." taken from:-
http://en.wikipedia.org/wiki/Red_hair#Beliefs_about_temperamentThe rest of the paragraph goes on with superstitious comparisons between redheads and vampires(note how vampires have a strong sexual aspect in mythology).
Notice that the sole proposed benefit is better vitamin D absorption, lending further credence to the sunlight and dietary hypotheses.
Actually, redheads have been cited as being more sensitive to pain(which can actually be an advantage if you think about it, warning more often against possible injuries):-
http://en.wikipedia.org/wiki/Red_hair#Sensitivity_to_pain_and_injuryAlso, Wikipedia mentions a study which claimed that the sheer vividness of red hair and its rarity value led to a positive sexual selection pressure for red hair:-
http://www.ncbi.nlm.nih.gov/pubmed/15372380Oh, and here's a reference to a study on German women in general which showed that redheaded women have more sex and more partners. That would certainly imply a strong sexual selection trait in favour of redheads:-
http://www.dailymail.co.uk/news/article-400779/Redheads-sex-blondes-brunettes.htmlThis may help explain why blue/green eyes are spread more diffusely across the globe
That merely happened because of light-skinned conquering peoples invading the various areas, nothing to do with climate or anything else.
and why blond hair is found among Australian aborigines.
Strictly speaking, the Aboriginal blond hair isn't blond, it involves a gene or two which causes a lack of pigmentation creating a blond-like colour. Which is interesting as a gene for such a paler trait shouldn't appear in the tropics if the climate/Vitamin D theory was correct.
Some Problems With Sunlight As The Sole Factor:
Why were pre-intermixed Sami peoples darker than Scandinavians, despite the fact that the Sami lived farther north and were there before the arrival of the Scandinavians?
The Sami only became distinct from other populations c.10,000 years ago, judging from the data, nowhere near enough time for such a dramatic change to paler skin to occur. Even then, they've always intermixed with Scandinavian populations, Finno-Ugric peoples etc.:-
http://en.wikipedia.org/wiki/Sami_people#Genetics_and_the_history_of_genetic_studies_on_the_SamiAnyway, any claims re the Sami and darker skin are arbitrary, just look at the photos on the above link, you'll find not too many dark-skinned examples of the Sami people, to put it mildly!
Why are coastal and Nile delta Africans so much lighter than peoples just south of the fertile coastal and river valley areas? European intermixing does not appear to explain it completely.
Actually, it does. Bear in mind that Arabs(who have hefty Caucasoid admixure) invaded those areas, along with the blue-eyed Sea Peoples in the far past etc.
Why are western Europeans lighter in skin color than eastern Europeans at the same latitude?
Ahem! Having visited Western European and Eastern European countries frequently and knowing people who've been elsewhere in Eastern Europe(I'm part-Austrian and lived in Austria for many years), I can attest to the fact that this is just not true. If you'd been to Leningrad or Kiev or Slovakia/Bratislava, for example, you would have seen a remarkably high number of pale-skinned blonde-haired/blue-eyed people walking the streets.
I think this factor is probably the consensus because it's so intuitive and doesn't threaten the profits of the food industry, in addition to the supporting evidence. Yet the consensus answer appears to leave unanswered my above questions. Why did this adaptation to low levels of sunlight with the palest of skin, blond and red hair, and blue/green eyes occur in Scandinavia and the British Isles, but not in Arctic Asia or North America?
Ah, but like I said, there is no proof whatsoever that blue eyes or blond hair originated in Europe.Many people view western Siberia or the Caucasus or other regions as far more likely places of origin for those characteristics. And, it's impossible for those traits to have appeared in North America as humans only entered that continent c. 15,000 years ago, the geentic change would have been too slow to occur in that period.
That's where the dietary hypothesis of Cordain and others may come in. The northwestern Europeans reportedly adopted wheat and bovine dairy as staple foods earlier and more thoroughly than the indigenous Arctic Asians or North Americans.
Like I said before, the dietary notion is utterly destroyed by the fact that those populations in the Middle-East and elsewhere which adopted grain-/dairy-filled diets long before Northern Europeans did, have not developed skin-colour as pale or paler than Northern Europeans.
Conclusion: MultifactorialI don't know any prominent Paleos who believe all genetic and epigenetic change stopped 10,000 years ago. Can you point me to where they say this so I can check it out?
This is just ridiculous. You know as well as I do, that the vast majority of palaeolithic anthropologists claim that, genetically, we are virtually identical to palaeo humans. Incidentally, epigenetics only changes gene-expression, it can't change/mutate genes completely to produce completely different colours.
Here is an excerpt from beyondveg.com citing a study re this:- "Humans may have indeed eaten these foods for "millennia," but millennia (even 10 millennia) in the overall timeframe of human existence represents 0.4%. Because the estimated amount of genetic change (0.005%) which has occurred in the human genome over this time period is negligible, the genetic makeup of modern man has remained essentially unchanged from that of pre-agricultural man [Eaton et al. 1985]" taken from :-
http://www.beyondveg.com/cordain-l/grains-leg/grains-legumes-1a.shtmlThe irony is that Cordain wrote that himself, thus detroying his absurd claim that a Neolithic diet could lead to paler skin. Besides, if Australian Aborigines could develop blond/pale hair on their Palaeolithic diet, then it's obvious that such a dietary notion is patently absurd.
Most of the sources I've read said that the Inuit originated from Siberian Asia. Hardly tropical.
I have my doubts, the few Inuit who are really dark-skinned tend to have the kind of dark skin found in more southerly latitudes. All those sources can claim is that the Inuit had to move from Siberia to North America via the Bering Strait. There's no real evidence to suggest that they didn't migrate into Siberia from other parts before that period.
I think this could be the crux of the matter. Your results have been less positive in general than most Paleo dieters I'm familiar with, which may explain your tendency to dismiss suggestions that diet may be related to unusual health improvements and other natural phenomena.
Utter balderdash. If you had read my testimonial on rawpaleodiet.com, you would have noticed that my health-improvements have been quite remarkable on this diet, certainly far greater than any cooked-palaeo's experience, and on a par with many RPDers(if one counted every minor to major symptom I got rid of, it would come to something like 60-80 of them). It's merely that I have come across so many absurd claims from numerous gurus claiming miraculous healing properties from foods(Hulda Clarke/Marshall protocol etc. etc.) that I don't believe that diet is a cure-all for almost everything. My experience on raw boards/forums is that for people with very serious conditions(like I had) it can take a long time for full recovery(though there were dramatic initial improvements) and that some conditions(eg:- genetic-related) are indeed largely irreversible(ie autistics can heal their digestive system/improve their mood on this diet but not cure their actual condition etc.)
Show me where Cordain promotes magic or superstition in his scientific analysis of diet and skin color. You have cited him yourself before so I'm surprised you would associate his research with superstition.
I was actually suggesting, in the past, that you were prone to superstition, not Cordain(all those Noble Savage references, remember). As for Cordain, he seems to have really shot himself in the foot with that unproven acid/alkali theory of his. He seems not to have done much in the way of truly groundbreaking research and , more or less, relied on other scientists to provide this, which makes me sceptical of him. The only benefit I see in him is that he promotes some aspects of cooked palaeo(if not all the good ones) and is therefore a little right(and mostly wrong) from our POV.