Saturday, October 20, 2012

When Europeans turned white


No, that’s not a climatic adaptation
(actress Lily Cole - source)


“European skin turned pale only recently”—such was the headline in Science five years ago. 

[…] a new report on the evolution of a gene for skin color suggests that Europeans lightened up quite recently […]  the implication is that our European ancestors were brown-skinned for tens of thousands of years (Gibbons, 2007)

The report had been presented by a postdoc, Heather Norton, at the annual meeting of the American Association of Physical Anthropologists (Norton & Hammer, 2007). Over the following years, I e-mailed periodically to ask her when the study would be published. To make a long story short, she landed a faculty position and found herself overwhelmed by new responsibilities. There were still problems with the dating of this genetic change, and time couldn’t be found to work them out. So the study stayed “on the back burner.”

Five years later, the study has finally been published … by another research team. Beleza et al. (2012) generally confirmed Norton’s preliminary finding but found evidence that Europeans had lightened through a 2-stage process. Around 30,000 years ago, not long after entering Europe, the ancestors of today’s Europeans and East Asians lightened in skin color through a new allele at the KITLG gene. But the real whitening came much later, between 19,000 and 11,000 years ago among ancestral Europeans only, through new alleles at TYRP1, SLC24A5, and SLC45A2. This finding strikes down the two leading explanations for the whiteness of European skin:

1.     As modern humans spread north from Africa and into higher latitudes with less solar UV, their skin had to lose pigmentation to maintain the same level of vitamin-D synthesis. Europeans therefore began to turn white once their ancestors entered European latitudes some 40,000 years ago (Loomis, 1970; Murray, 1934).

This explanation might account for the initial loss of pigmentation circa 30,000 BP, when ancestral Europeans probably became as light-skinned as Amerindians. But it cannot explain the much greater loss of pigmentation more than twenty thousand years later.

2.     Some writers, like Sweet (2002), have suggested that the transition from hunting and gathering to farming increased the body’s need for vitamin D (because cereals contain phytic acids that immobilize calcium and phosphorus within the body and because a high-meat diet seems to reduce vitamin-D requirements). In Europe, however, this transition began only 8,000 years ago and did not reach northern Europe until 7,000-3,000 BP.

Beleza et al. (2012) suggest that a colder climate forced Ice Age Europeans to wear more clothing and spend more time in shelters, thus reducing their exposure to solar UV. It was thus at that time, and not when modern humans first entered Europe, that European skin turned white in order to maintain the same level of vitamin-D synthesis.

But then why didn’t Europeans revert after the Ice Age to their original brown color? And why do we see brown skin in humans who have long lived with weaker solar UV and even colder weather in northern Asia and North America? This is notably the case with Amerindian groups in Canada and Alaska who derive very little vitamin D from either the sun or their diet (Frost, 2012a, 2012b).

In any case, it is only during the summer that solar UV is intense enough for the skin to synthesize vitamin D. Yet European summers were not much cooler during the last ice age than they are today. The Central Russian Plain, for instance, had a July mean temperature of 16° back then, versus 18° now (Hoffecker, 2002, p. 23). So Ice Age Europeans had little reason to be less exposed to solar UV. Indeed, the open steppe-tundra was much more exposed to the sun than the forested environments before and after the Ice Age.

Sexual selection?

There remains of course my explanation (Frost, 2006; Frost, 2008). White skin was not climatically advantageous. It was visually advantageous, as were two other unique color traits. Within this same geographic area, centered on northern and eastern Europe, hair is not only black but also brown, flaxen, golden, or red. Eyes are not only brown but also blue, gray, hazel, or green.

Yet, in each case, the genes are different. European skin lightened mainly through replacement of alleles at three genes: SLC45A2, SLC24A5, and TYRP1. European hair color diversified through a proliferation of new alleles at the MC1R gene. European eye color diversified through a proliferation of new alleles in the HERC2-OCA2 region and elsewhere.

These European color traits have evolved along separate trajectories, yet the goal seems similar—a shift toward brighter and more visible colors. But visible to whom?

To the opposite sex? Sexual selection favors visual qualities that catch the attention of potential mates. In the case of skin color, a pre-existing sexual dimorphism has made lighter skin a visible female characteristic. Women are the “fair sex.” They’re paler than men from puberty onward (Edwards & Duntley, 1939).

Skin color is, in fact, a key visual cue for sex recognition, being even more crucial than face shape (Bruce & Langton, 1994; Hill, Bruce, & Akamatsu, 1995; Russell & Sinha, 2007; Russell et al., 2006; Tarr et al., 2001; Tarr, Rossion, & Doerschner, 2002). When shown a human face, subjects can recognize its sex even if the image is blurred and differs only in color (Tarr et al., 2001).

The specific cues are hue and luminosity. A man is browner and ruddier in hue than a woman because melanin and blood are more present in his skin’s outer tissues (Edwards & Duntley, 1939). A woman has higher luminous contrast between her facial skin and her lips or eyes (Dupuis-Roy et al., 2009; Russell, 2003). These cues may explain the similar evolution of cosmetics in a wide range of culture areas, i.e., women generally seek to lighten their facial color and to increase its contrast with their lip and eye color (Russell, 2003; Russell, 2009; Russell, 2010).

Thus, the more a woman is lighter-skinned, the more she is recognizably female. This is not just a matter of conscious sex recognition. It’s also a matter of men acting on half-conscious feelings. Even when a woman is recognized as such, her mating success may be influenced by subtle differences in the way men perceive her femininity.

Extreme sexual selection on the European steppe-tundra

But if sexual selection were the cause, why did it occur only 19,000 to 11,000 years ago and only in Europe? What was so special about that time and place?

That time frame coincides with the last ice age (25,000-10,000 BP), particularly the glacial maximum (20,000-15,000 BP). In Europe, especially on the northern and eastern plains, there were now vast expanses of steppe-tundra that supported herds of wandering reindeer and other herbivores, which in turn supported a large human population. Bioproductivity was in fact much higher there than on today’s arctic barrens. Steppe-tundra also existed in Asia, but it was colder and drier, being farther north and farther from the moderating influence of the Atlantic Ocean. Its human population was not only smaller but also more vulnerable to periodic extinctions, particularly at the height of the last ice age.

Europe’s steppe-tundra was a singularity among the many environments that modern humans encountered as they spread out from Africa during the Paleolithic. It offered an abundance of food, but almost all of the food was in the form of meat. Since hunting was primarily a male activity, men had to bear almost the entire burden of food provisioning. Women either processed the food that men supplied or did activities unrelated to food, such as garment making or shelter building.

There were also demographic consequences. First, polygyny became less common, being limited to those able hunters who could support more than one family. Second, the death rate among young males increased. In hunter-gatherer societies, the male death rate increases with hunting distance, reaching a maximum in environments where hunters pursue migratory herds over long distances. As a result, women greatly outnumbered men on the mate market. Women had to compete for the attention of potential mates, and sexual selection favored the mating success of those who could.

In other species, sexual selection changes physical appearance from a dull, cryptic coloration to a brighter, more eye-catching one. This is especially true for traits on or near the face—the focus of visual attention. Since most genes for human skin, hair, and eye color are not sex-linked, any selection for new color traits in one sex would spill over onto the other sex. As European women whitened, so did Europeans of both sexes.

In time, sexual selection also leads to sexual dimorphism. Sex-linked alleles would appear through random mutation and gradually replace similar alleles that are not sex-linked. Some sexual dimorphism is indeed evident in European color traits. A twin study has shown that hair is lighter-colored in women than in men, with red hair being especially more frequent, and that women show greater variation in hair color (Shekar et al., 2008). Skin color, however, is actually less dimorphic in light-skinned humans than in those of medium skin color, probably because of a “ceiling effect,” i.e., girls cannot become much lighter-skinned after puberty if the population is already close to the limit of maximum paleness (Frost, 2007).
 
Conclusion

White European skin evolved relatively fast during the last ice age, specifically from 19,000 to 11,000 years ago. This was also probably the same time frame for the evolution of European hair and eye colors. Anyway, that’s my bet.

These color traits—white skin and a diverse palette of hair and eye colors— are not adaptations to a cooler, less sunny climate. They are adaptations by early European women to intense mate competition, specifically a shortage of potential mates due to a low polygyny rate and a high death rate among young men.

This situation was created by the steppe-tundra that covered most of Europe as late as 10,000 years ago. Early Europeans were able to colonize this environment but only at the price of a severe imbalance between men and women on the mate market.

References

Beleza, S., A. Murias dos Santos, B. McEvoy, I. Alves, C. Martinho, E. Cameron, M.D. Shriver, E.J. Parra & J. Rocha.(2012).The timing of pigmentation lightening in Europeans, Molecular Biology and Evolution, 20, online

Bruce,V., & S. Langton. (1994). The use of pigmentation and shading information in recognising the sex and identities of faces, Perception, 23(7), 803–822.

Dupuis-Roy, N., I. Fortin, D. Fiset, & F. Gosselin. (2009). Uncovering gender discrimination cues in a realistic setting, Journal of Vision, 9(2), 10, 1–8. http://journalofvision.org/9/2/10/, doi:10.1167/9.2.10.

Edwards, E.A. & S.Q. Duntley. (1939). The pigments and color of living human skin, American Journal of Anatomy, 65, 1-33.



Frost, P. (2012a). Vitamin D deficiency among northern Native Peoples: a real or apparent problem? International Journal of Circumpolar Health, 71, 18001 - DOI: 10.3402/IJCH.v71i0. http://www.circumpolarhealthjournal.net/index.php/ijch/article/view/18001

Frost, P. (2012b). Reply to W.B. Grant ‘Re: Vitamin D deficiency among northern Native Peoples’ International Journal of Circumpolar Health, 71, 18435 - DOI: 10.3402/ijch.v71i0.18435 http://www.circumpolarhealthjournal.net/index.php/ijch/article/view/18435/pdf_1

Frost, P. (2008). Sexual selection and human geographic variation, Special Issue: Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society. Journal of Social, Evolutionary, and Cultural Psychology, 2(4),169-191. http://137.140.1.71/jsec/articles/volume2/issue4/NEEPSfrost.pdf

Frost, P. (2007). Comment on Human skin-color sexual dimorphism: A test of the sexual selection hypothesis, American Journal of Physical Anthropology,133, 779-781.
http://onlinelibrary.wiley.com/doi/10.1002/ajpa.20555/abstract

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103 http://www.sciencedirect.com/science/journal/10905138

Gibbons, A. (2007). American Association Of Physical Anthropologists Meeting: European Skin Turned Pale Only Recently, Gene Suggests. Science 20 April 2007:Vol. 316. no. 5823, p. 364 DOI: 10.1126/science.316.5823.364a
http://www.sciencemag.org/cgi/content/summary/316/5823/364a

Hill, H., V. Bruce, & S. Akamatsu. (1995). Perceiving the sex and race of faces: The role of shape and colour, Proceedings of the Royal Society B: Biological Sciences, 261, 367–373.

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe, Rutgers University Press.

Loomis, W.F. (1970). Rickets. Scientific American, 223, 77-91.

Murray, F.G. (1934). Pigmentation, sunlight, and nutritional disease. American Anthropologist, 36, 438-445.

Norton, H.L. & M.F. Hammer (2007). Sequence variation in the pigmentation candidate gene SLC24A5 and evidence for independent evolution of light skin in European and East Asian populations, Program of the 77th Annual Meeting of the American Association of Physical Anthropologists, p. 179.

Russell, R. (2010). Why cosmetics work. In Adams, R., Ambady, N., Nakayama, K., & Shimojo, S. (eds.) The Science of Social Vision. New York: Oxford.

Russell, R. (2009). A sex difference in facial pigmentation and its exaggeration by cosmetics. Perception, 38, 1211-1219.

Russell, R. (2003). Sex, beauty, and the relative luminance of facial features, Perception, 32, 1093-1107.

Russell, R. & P. Sinha. (2007). Real-world face recognition: The importance of surface reflectance properties, Perception, 36, 1368-1374.

Russell, R., P. Sinha, I. Biederman, & M. Nederhouser. (2006). Is pigmentation important for face recognition? Evidence from contrast negation, Perception, 35, 749-759.

Shekar, S.N., D.L. Duffy, T. Frudakis, G.W. Montgomery, M.R. James, R.A. Sturm, & N.G. Martin. (2008). Spectrophotometric methods for quantifying pigmentation in human hair—Influence of MC1R genotype and environment. Photochemistry and Photobiology, 84, 719–726.

Sweet, F.W. (2002). The paleo-etiology of human skin tone. http://backintyme.com/essays/?p=4

Tarr, M.J., D. Kersten, Y. Cheng, & B. Rossion. (2001). It’s Pat! Sexing faces using only red and green, Journal of Vision, 1(3), 337, 337a, http://journalofvision.org/1/3/337/, doi:10.1167/1.3.337.

Tarr, M.J., B. Rossion, & K. Doerschner. (2002). Men are from Mars, women are from Venus: Behavioral and neural correlates of face sexing using color, Journal of Vision, 2(7), 598, 598a, http://journalofvision.org/2/7/598/, doi:10.1167/2.7.598.


32 comments:

Beyond Anon said...

You are beating a dead horse!

I believe you already.

Anonymous said...

By the way, gender is a grammatical construct. Sex is the biological term you want.

Anonymous said...

James Bowery wrote up a similar theory of selection on the European steppe-tundra among Paleolithic Europeans:

http://majorityrights.com/weblog/comments/of_penguins_paleolithic_gender_ratio_and_white_fertility

"The emperor penguin and paleolithic europeans… is there a similarity?

Perhaps—if you consider the difficulty of reproducing in harsh environments. Of course, not all winter-adapted creatures are subject to the extreme conditions borne by the emperor penguin of the antarctic ice flows but keep in mind that humans were subject to enough environmental pressure to evolve technological culture—something unique among animals. Moreover, among the strongest selective pressures posited for human evolution are fatal accidents suffered primarily by males. This is similar to the emperor penguin’s extraordinarily high male mortality rate suffered due to the difficulty of gathering calories for the young.

Such gender-selection against reproductive-age males produces an abundance of reproductive age females. Now the emperor penguin isn’t unique in having an abundance of reproductive age females due to high male mortality—but in most other species the result would simply be larger harem sizes for the males. Not so for the emperor penguins who are subject to ecologically imposed monogamy. Male provision for young among emperor penguins is as critical as female provision.

The combination of high female to male ratio with ecologically imposed monogamy results in something quite rare among the animals:

Female emperor penguins fight over males during courtship season but males do not fight over females.

Now, consider the possibility that paleolithic whites, subject to both of these same conditions—high male mortality rate combined with ecologically imposed monogamy of environments low in food calories—may have evolved similar adaptations."

Tyrion Lannister said...

Mr. Frost,

I agree with your hypothesis on evolution of European hair, eye and skin color by sexual selection. Do you think special enviroment and natural selection pressures were affecting European shape face? Or Does sexual selection modifies genes thought to be involved in face shape (PRDM16, PAX3, TP63 C5orf50, COL17A1, etc..)?
Europeans have smaller faces (l ong and narrow face narrow, high nasal opening, sloping eye obits, sharp inferior nasal border, larger nasal spine,...) than most non-European populations , on average, in spite of being taller and heavier than many non-European populations.

Sean said...

According to 2011 report on vitamin D commissioned by the US and Canadian governments from the National Academies Institute of Medicine - Page 104-106. "Kimlin et al. (2007), using computer modeling, concluded that it may no longer be correct to assume that vitamin D levels in populations follow latitude gradients. Indeed, the relationship between UVB penetration and latitude is complex, as a result of differences in, for example, the height of the atmosphere (50 percent less at the poles), cloud cover (more intense at the equator than at the poles), and ozone cover. The duration of sunlight in summer versus winter is another factor contributing to the complexity of the relationship. Geophysical surveys have shown that UVB penetration over 24 hours, during the summer months at Canadian north latitudes when there are many hours of sunlight, equals or exceeds UVB penetration at the equator (Lubin et al., 1998). Consequently, there is ample opportunity during the spring, summer, and fall months in the far north for humans (as well as animals that serve as food"
(It's true UVB is absent for several months in the winter. But)
"Studies of modest weight loss have found the circulating 25OHD levels to increase despite no increased intake of vitamin D from diet or sunlight exposure (Riedt et al., 2005; Reinehr et al., 2007"

So given a bit of weight loss in that part of coldest season when hunting would be worst, the blood vitamin D level would fall a bit, but not too much.

Chris Crawford said...

Peter, do you think there's promise in applying this hypothesis to other components of perceived female sexual attractiveness? Most of these components of which I'm aware already have an explanation in health and fecundity (large breasts suggests good milk production, large hips suggest better birth survivability, symmetric features imply early health).

Can we detect behavioral differences in Europeans consisten with your hypothesis? Are European women more prone to smile, more subservient to males? Here's one question for which I doubt you'll find much data: are European women better in bed? ;-)

Conversely, can we find evidence of selection against traits now thought to be ugly? Are long hooked noses less common among Europeans? Big feet?

You mentioned a possible correlation between female appearance and infant appearance; could this be examined in other dimensions? Is the ratio of finger length to palm size lower in European females than males? Eye size to head size? Head size to body size? Is the higher tone of female voice solely due to shorter vocal cords arising from smaller body size, or does it exceed the expected value?

Sean said...

Re. Beleza suggestion about covering up would lead one to expect whites would make a lot of vitamin D when exposure was on face and hands. But, Bogh 2012 found "no significant solar-induced Δ25(OH)D was observed when sun-exposed areas were limited to hands and face."
Some light on the photobiology of vitamin D "A smaller substudy suggests that skin pigment is not a barrier to vitamin D photosynthesis."

Hence it's unlikely white skin evolved to make more vitamin D. Even if UVB intensity meant there was suboptimal synthesis of vitamin D in northern Europe (which it didn't), or if Europe 15,000 years ago was so cold that people had to cover up in the middle of summer (they didn't).

Some light on the photobiology of vitamin D notes the importance of "baseline vitamin D status in conducting such studies". IE there is a feedback mechanism to limit vitamin D synthesis in white people.

Quite apart from pigmentation, there are various mechanisms that evolved to limit vitamin D synthesis under feedback from existing blood levels and stores. As the above findings (especially the one about baseline levels shows), north Europeans do not maximize vitamin D synthesis.

"European color traits have evolved along separate trajectories"[to skin color]
So why do people continue to imply hair and eye pigmentation is a side effect of genes for light skin. Is it because no one has ever come up with a use for diversified hair and eye colors apart from sexual selection?

Ben10 said...

Peter, even since I've read your blog for the last 3 years, i still don't understand something in your theory.
You said :"...But the real whitening came much later, between 19,000 and 11,000..." Big difference between 19 and 11, but Ok, that's during the last glaciation then, which ended ~12000 years ago if I'm correct.
So your sexual selection in the european toundra works BUT now, explain this:

1)Hunters gatherers in the toundra can not be as many as the mutiple waves of farmers immigrants that came later from further south.
2) These middle east farmers didn't have the same environmental pressure you describe, somehow they must have been bronwish/bronze, like otzi maybe.

Question: But ALL europeans ended up WHITE. How can a minority of RECESSIVE white genes wins over a majority of DOMINANT brown genes, even from within the north european populations themselves?

If we put 10 millions africans, say in Ireland, wouldn't we expect to see a majority, if not all, of 'Irish' turn brown in a few generations?

In earlyer posts you answered, saying that some brownish isolate persisted in north europe, but there is no evidence of that. Also, when we consider incoming populations that were not subjected to the sort of selection you describe, the problem becomes even worse. You said that girls with white genes were snatched and 'travelled long distances' to whitten the brown immigrants. Well, there was no highwways in 10000 bc, but even if it was true, how a minority of white girls with RECESSIVE genes snatched from the north could convert incoming population, when the environmental pressure for fewer men than women had disapeared in these propulations?

In short, your theory would work perfectly IF white genes were dominant, but they are not. That's why i suggested that in addition to the mechanisms you describe, the white genes carriers must have had some sort of strong selective advantage over their earlier brown ancestors, which was not related to vitamineD or sexual selection.

Mac said...

Chris Crawford.

...Most of these components of which I'm aware already have an explanation in health and fecundity (large breasts suggests good milk production, large hips suggest better birth survivability, symmetric features imply early health).

1- Human breast size does not influence how much breast milk produce. Because breast size depends more on the amount of supporting fibrous and fatty tissue than the amount of milk glands. Therefore women with larger breasts do not necessarily produce more breast milk. Breast milk production is stimulated hormonally and increases with demand.

2- It is not hips size that determines the space a baby has to travel through the birth canal, but the width and shape of the pelvis - the part of the body which contracts and pushes the baby out into the world. If a woman has hips that looks childbearing, this doesn't necessarily mean she has a wide pelvis. There is no test to prove how wide or narrow a pelvis is - the only way to find out is to give birth!

The key piece in all of this is that question is hourglass shape because that is a sign of fertility, of whether women with 0.65-0.70 WHRs are really more fertile. As it turns out, women with smaller WHRs get pregnant more readily. Women with a relatively low waist-to-hip ratio and large breasts have about 30 per cent higher levels of the female reproductive hormone estradiol than women with other combinations of body shapes. Waist-to-hip ratio also had a strong effect on levels of another female hormone, progesterone.


Men find more attractive those women who are likely to be fertile and nubile, i.e. able to get pregnant. Women with smaller waists and wider hips mean aren't obviously pregnant, tend to be younger, have more circulating estrogen and all of which are associated with higher fertility.

Ben10 said...

... your theory works perfect IF the white genes were dominant (or at least less recessive in that time) OR, if the white genes carriers became the majority during a short period of time, like an 'extinction event'.

One might think about an epidemy similar to the great pests, who supposedly are responsible for the predominance of the blood type A in Europe.
But i am also thinking about two cataclysmic events, unless they are the same:
The end of Atlantis as mentioned by Plato, around 9000 bc, and the biblical Deluge.

Sean said...

Chris, Re. looks: The eye of the beholder? . As for behaviour,it seems to me that in a population where there was sexual selection of women we would see intensification of women's feminine traits in looks and behaviour. I think promiscuity is masculine behaviour, and it would be reduced in women by sexual selection (of women).

What we would see more of is typical feminine behaviour. such as hesitant acquiescence to the advances of a favoured male. It has to be remembered that white women's sexual behaviour is a function of the liberalism of white societies which allow women a degree of sexual freedom that is inconceivable elsewhere in the world.

Anonymous said...

Peter, this is OT but you've blogged or mentioned before on your blog that girls are maturing faster and reaching puberty earlier. Well it appears to be happening to boys as well:

http://edition.cnn.com/2012/10/20/health/boys-early-puberty/index.html

"Boys in the United States are starting puberty earlier than ever, according to a new study publishing in the November issue of the journal Pediatrics.

In the study, lead author Marcia Herman-Giddens from the University of North Carolina's School of Public Health and her colleagues show that boys are starting to sexually develop six months to two years earlier than medical textbooks say is standard."

"Researchers assigned each boy's data to one of five stages -- Stage 1 being pre-puberty, Stage 2 being the onset of puberty and Stage 5 being adult maturity. They then compared the ages and puberty stages of all the boys. The rigorous study was designed to report on only physical changes, not hormonal.

The results were broken down by race: African-American boys start hitting Stage 2 first, at about 9 years old, while non-Hispanic white and Hispanic boys begin developing around 10 years old. "This should have an impact on the public health community," Herman-Giddens said.

But the researcher is concerned about using the numbers as a new standard for pediatricians. "That might be normal now," she said, "but that doesn't mean it's normal in the sense of what's healthy or what should be."

One of the reasons she's worried is that our environment may be playing a role in accelerating puberty.

"The changes are too fast," Herman-Giddes said. "Genetics take maybe hundreds, thousands of years. You have to look at something in the environment. That would include everything from (a lack of) exercise to junk food to TV to chemicals.""

Chris Crawford said...

Thanks for straightening me out on breasts and hips, Mac and Sean. There are still lots of traits that I mentioned that might be useful for confirming or rejecting Peter's hypothesis.

Sean said...

Peter has a book about light skin colour being favoured in a wide range of traditional cultures. I gave a link which shows that white women are regarded as relatively attractive, and were even in the days before Westernization of global culture.

And at that link it says: "female raters, (14 were White, 3 were Black, and 3 were Asian) gave the highest ratings to Black men. It's difficult to explain that unless Peter is right.

Peter Fros_ said...

Beyond Anon,

If only the horse were dead! The vitamin-D explanation for white European skin is like the Terminator. You think you've killed it, and it comes back to life in a new form.

Anon,

Point taken. The text has been changed.

Anon,

I wasn't aware of that article by James Bowery. This may be a case of convergent thinking. Or he may have picked up from me indirectly. I first published this hypothesis back in 1994:

Geographic distribution of human skin colour: A selective compromise between natural selection and sexual selection? Human Evolution, 9, 141-153.

Tyrion Lannister,

Yes, I believe that the same intensifcation of sexual selection influenced European face shape.

See:
http://evoandproud.blogspot.ca/2009/09/female-face-shape-and-sexual-selection.html

Sean,

The vitamin-D hypothesis is one of the three big obstacles I encounter. It has a strong hold on people's thinking, and I'm not sure whether Beleza et al's study will be enough to knock it out of the running.

Chris Crawford,

Yes, I believe it can be applied to other aspects of female attractiveness. Women of European descent have wider hips, narrower waists, and thicker subcutaneous fat than do women of other geographic origins. I touch on these points in my 2006 and 2008 articles (go to My Publications).

I suspect that blushing is more developed in European women, but the data are sparse. I prefer to focus my energies where I have the best chances of winning this argument.

Ben,

Yes, this is the other obstacle I encounter. "Since Middle-Eastern farmers replaced European hunter-gatherers, everything that happened in Upper Paleolithic Europe is irrelevant."

Most paleoanthropologists believe that less than 25% of the current European gene pool comes from these Middle-Eastern farmers. Others, like Greg Cochran, disagree, and I've dealt with their arguments at some length in previous posts, such as:

http://evoandproud.blogspot.ca/2012/05/who-were-ancestors-of-modern-europeans.html

Farming came to northern Europe between 7,000 and 3,000 years ago. Egyptian tombs from 4,000 years ago have paintings of white-skinned, fair-haired Europeans. So, if Europeans had been demographically replaced by Middle Easterners, we're left with a time frame of only 3,000 years (maximum) during which these hair, eye, and skin color traits could have evolved. In any case, the time frame was much earlier, 19,000 to 11,000 years ago. That's long before farming came to Europe.

Anon,

Yes, boys are maturing earlier, but I wouldn't rule out a genetic explanation. In a word, the 'cads' are outbreeding the 'dads.'

Sean said...

The vitamin-D hypothesis is fateful; it mandates giving supplements of vitamin D to those (INCLUDING CHILDREN) with dark skin who live at northern latitude. If it was true Black Africans in the northernmost latitudes would all have severe rickets and much else wrong with them.

Mirco Romanato said...

The women surplus in Europe could have spilled in the near populations?

If a male could only support a female, it make sense to sell the surplus to other men. It would be better than let the die.

If the women sold were "prettier" than the women of the confining populations (but less of the women kept), they would reproduce with their new owner / husband faster than the local women.

Another point: if food was abundant but difficult to get, the old Europeans would have a surplus population spilling continuously to South and East.
They would have a difficult to invade homeland and the ability to push continuously outside.

Anonymous said...

So what's with the British being so white in particular and other people not finding them attractive?

Michael said...

Peter Frost,

You have said " There's very little sexual selection of women anywhere. In fact, an argument can be made that the pressure of sexual selection has now shifted to men. The 'European singularity' has been pretty much abolished.

What are your thoughts on social and Darwinian nature of this debate?,and about how human evolution has sped up in the last 10,000 years anticipated the future shape of human evolution would take given the sexual marketplace changes?. I wanted to know if the Four Sirens (contraceptives, easy peasy no-fault divorce, women’s economic independence, rigged feminist-inspired laws) would speed up human evolution even faster than the dawn of agriculture.
Contraception is a selective pressure? Catholicism and fewer years of education are both positively correlated with fertility? In possibly what will turn out to be the juiciest irony in all of human history, feminism and its co-ideologies of deceit may usher in a Western that looks more like a patriarchal Middle Eastern caliphate of their worst nightmares. The realization of the matricentric utopia that feminism has been clamoring for these last few generations will undo the very foundation upon which the rancid ideology was able to prop itself.

Economically independent women, freed from shame and the restrictions of their biology by the pill and abortion, following their vaginas straight into soft polygamy, state-supported single motherhood, and grossly unjust payday divorce settlements.
a great narcissism has flourished, leading women to overvalue themselves so much that they price themselves out of the dating market. Modern women are being more choosy and they are increasing their mate standards.

At this time religions and monogamous marriage can not enforced made sure all beta men have get a mate, thus unlocking productive output out of these men who a this times have no incentive to be productive. Surplus of bachelor men. Such surpluses of men increase the potential for internal and external violence, while diminishing the prospects for democracy? This phenomenon destabilize.

It would be interesting if you could discuss about this in a thematic post.

Mac said...

Peter,

"Yes, I believe it can be applied to other aspects of female attractiveness. Women of European descent have wider hips, narrower waists, and thicker subcutaneous fat than do women of other geographic origins . I touch on these points in my 2006 and 2008 articles (go to My Publications) ."

You have discussed to a trend toward lower waist-to-hip ratios among women in northern Europe, overall corresponding to some secondary sexual characteristics that tend to be more exaggerated in European women.
Although there is considerable heterogeneity in breast sizes within each population, Northern European women's average breast size tend to be larger than another populations- mongolides, Negroid ..-? And there are different features between Northern and Southern European women?

Sean said...

Peter, MtDNA analysis of global populations support that major population expansions began before Neolithic Time.

The vitamin D hypothesis advocates are about go very quiet. After the inevitable Y-chromosome study showing selection, your former critics will say the theory that Europeans originated in sexual selection of women was obvious all along.

Anonymous said...

On a related note, I think that east Asian women are turning white. Someone should do a comparison of photographs from a hundred years ago and today. It appears to me that round eyes and light skin are being selected for at a rapid rate among asians.

Anonymous said...

In Neanderthals, there was the whole range of hair colour we see today in modern European populations, from dark to blond right through to red. Out of Africa, the selective pressure from UV radiation disappears. So any mutation that falls into the MC1R gene is allowed to survive and spread through a population. This suggests that similar adaptations were evolved independently by Neanderthals and modern Europeans in response to similar environmental circumstances.

Whiteness is more likely to have evolved within the Neanderthals who inhabited areas where white skin would be an evolutionary advantage for hundreds of thousands of years before the two species met, or perhaps even predecessor non-African species. Neanderthals would then have interbred with Sapiens, producing offspring with ever-lighter skin. The idea isn't impossible. Anaway it seems humans and Neanderthals only overlapped in a few places that we now of, notably in the Middle East and in Southern Russia. Neither of these are places known for inhabitants with especially pale skin. So if pale skin did come from Neanderthals, it migrated North with Sapiens and died out from the areas that Neanderthals existed. But, this isn't impossible.

The next issue is that Australian Aborigines lived in environments on the same latitude as New York or Spain at the height of the last ice age and for at least 10, 000 years before. They never evolved light skin any more than tropical Americans evolved dark skin. All this doesn't prove very much at all except that skin colour really isn't as plastic as people often assume it, nor is it as large a survival trait as people often assume it is. There's no doubt that it is somewhat plastic, and that it offers some survival advantage, but either plasticity or advantage is so low that it doesn't alter in over 20.000 years at latitude lower than those at which humans an Neanderthals predominantly overlapped

Anonymous said...

"On a related note, I think that east Asian women are turning white."
That's absurd but funny.

Ben10 said...

Peter, your theory will be blocked for its political consequences.

Here is what it means to accept your theory in political terms:
1)Whites today are the result of sexual selection taking place for thousands of years.
2)This reproduction behavioral pattern has been genetically hardwired in the brain of white males and is expressed very strongly during the male reproductive age.
Technically, it should even be possible to look for genetic markers of this behavior.

3)This inherited ancestral behavior is called 'racism' in modern language and for the last 60years or so has been ruled from unwelcome in some rare white countries to unlawfull in most. This was not a problem as long as 'racism' was considered a moral deviance of (mostly) white males, as would be any criminal activity, but this becomes a problem if 'racism' is a genetic inheritence as much as the color of our hairs or eyes. Under these new terms, the french law that considers 'racism' unlawfull and punishable by prison, would become as stupid and arbitrary as labeling brown eyed people unlawfull and send them all in jail.
Then the case could be made that social behavior has amplified our imprited basal racist tendancies, but even the Law considers that the legal reponsability is diminished in genetically affected individuals.
The bottom line is that IF your theory was accepted, that would give some legal ground for people to challenge the anti-racist racist laws.
So, forget it.

Anonymous said...

Anonymous at 5:29:00, Don't believe me? Do a google images search such as "Korea 1900". Here is a good example:
http://www.paulnoll.com/Korea/History/Korea-1900-33.html

Then look at pictures of modern Korean women.

Anonymous said...

On the other hand, maybe I am wrong. I just came across this:
http://kdvr.com/2012/10/26/chinese-man-sues-wife-for-being-ugly-wins-120000/

Maybe it's just that plastic surgery is so common to get rounded eyes.

Anonymous said...

Then look at pictures of modern Korean women.

I'd tend to look at pictures of Europeans and Koreans together as a reference.

East Asian people are very particular with how they light their pictures - it changes the reflectance and brightness a lot.

Check out European girls who are into Asian fashion lighting their photos the same way and you'll see what I mean. Their skin looks a lot brighter than in "reality".

Iain said...

This sounds plausible, but it seems like it's missing a few steps. What about lighter skin hues in other parts of the world - the Middle East, southern Asia, the Americas? Female sexual selection among steppe hunters doesn't seem to fit there. I guess there could be a lack of selective pressure for dark skin when humans moved out of Africa, but what is that selective pressure, and why is it different between say, the rainforests of Congo and Brazil?

blackhead said...

In Europe and especially the UK and Ireland, tanned skin is seen as the most attractive because of its ability to adapt to the changing sun levels throughout the year.

Women with the palest complexions aren't seen as the most attractive.

Anonymous said...

"1)Hunters gatherers in the toundra can not be as many as the mutiple waves of farmers immigrants that came later from further south.
2) These middle east farmers didn't have the same environmental pressure you describe, somehow they must have been bronwish/bronze, like otzi maybe."

1) The middle-east farmers may have been lighter then than they are now.

2) The farmers may have been restricted to only some of the available terriotory through their crops not being fully adapted to the climate.

3) The farmers may have sparked a population boom among the northern hunter-gatherers through introducing domesticated animals particularly cattle.

4) There are numerous historically recorded examples of northern backflow at various times and perhaps more that are unknown particularly if the incoming agricultural zone was more fragile than a theoretical cattle-herding zone.

5) If traits had evolved for sexual selection then as long as the mid-east expansion wasn't continuously reinforced those northern traits might be preferred over time i.e. if elites picked northern trait females and elites had larger numbers of surviving offspring.

barakobama said...

This is wrong Europeans have ben white for at least 10,000-15,000ybp my reason is 4,000 year old bones of europeans that had migrated out of easern europe and landed in china all had white skin most had light hair and light eyes the oldest was a redhead and these people arrived in china 5,300 years ago as the afasasveo culture so 5,300 ybp there where nordic looking people they orignally came from eastern europe 6,000-7,000 ybp so those people where deffintly whit probably nordic looking the sammi people who's dna matchs 10,000 year old bones in northern ueorp MTDNA U5b have lived in northern europe for at least 10,000 years experts agreed their common ancestor with the rest of europe live 10,000 ybp sammi are completly white but have been isolated ofr 10,000 years they have the highets amount of blonde hair in the world the common ancestor of the pale eastern europeans and sammi lived about 10,000-15,000 ybp and would havebeen extremly white like nordic europeans have gotten tanner in the last 6,000 years from mid eastern inter marriage greeks have 50% mid eastern ydna and have as much mid eastern as european but are still white same with most southern europeans a part of the reason northern europe is paler is becaue they di dnot inter marry with mid easterns europeans have been white for at least 13,000 years the sardina people are decdants of hunter gathers in france but they have mainly mid easterrn blood today but are still white all of europe would have been white 10,000-15,000 ybp white skin did not travel and sread in europe it came from all europeans common ancestors experts belive the gene is 20,000 years old