When did early Europeans acquire their palette of eye colors? And their palette of hair colors? That question may soon be answered with retrieval of ancient DNA. (source: Dipoar)
As the new year begins, I’m particularly interested in the following topics.
When did Europeans begin to look European?
It seems that this evolution took place between 20,000 and 10,000 years ago—long after modern humans had arrived in Europe some 40,000 years ago. This is when Europeans acquired their most visible features: white skin, multi-hued eyes and hair, and a more childlike face shape. In my opinion, such features were an adaptation not to weak sunlight but to a competitive mate market where men were scarce because they were less polygynous and more at risk of early death. This situation prevailed on the European steppe-tundra of the last ice age, whose high bio-productivity made possible a relatively large human population at the cost of a chronic oversupply of mateable women. The result was an unusually intense degree of sexual selection.
If we look at European hair color, eye color, skin color, and face shape, all of these visible features seem to have assumed their current appearance through a selection pressure that acted primarily on women. It is European women who have pushed these evolutionary changes to their farthest extent:
- Hair color varies more in women than in men. Redheads are especially more frequent among women (Shekar et al., 2008).
- Eye color varies more in women than in men when both copies of the so-called blue-eye allele are present. There is thus a greater diversity of female eye colors in regions where blue eyes are the single most common phenotype, i.e., northern and eastern Europe (Martinez-Cadenas, et al., 2013).
- Blue eyes are associated in men with a more feminine face shape (Kleisner et al., 2010; Kleisner et al., 2013).
- In all human populations, women are paler than men after puberty. This post-pubescent lightening is due to sexual maturation and not to differences in sun exposure (Edwards and Duntley, 1939; Edwards and Duntley, 1949; Edwards et al., 1941; van den Berghe and Frost, 1986). In women, lightness of skin correlates with thickness of subcutaneous fat and with 2nd to 4th digit ratio—a marker of prenatal estrogenization (Manning et al., 2004; Mazess, 1967). Admittedly, this sex difference is not greater in Europeans than in other populations, although it could not easily be otherwise, since Europeans of both sexes are so close to the physiological limit of depigmentation.
- European facial features seem to have assumed their present form through a selective force that acted primarily on women (Liberton et al., 2009).
While women are more diverse than men in both hair color and eye color, this greater diversity came about differently in each case. With hair color, women have more of the intermediate hues because the darkest hue (black) is less easily expressed (Shekar et al., 2008). With eye color, women have more of the intermediate hues because the lightest hue (blue) is less easily expressed (Martinez-Cadenas et al., 2013).
Some of these sex linkages may nonetheless share a common developmental cause, such as the prenatal surge of estrogen that feminizes the developing female fetus. Thus, eye color is linked to face shape only in males, perhaps because female face shape is hormonally overdetermined, i.e., all girls are exposed to enough estrogen in the womb to feminize their faces, but only blue-eyed boys reach this level of exposure.
We see a similar pattern with eye color and shyness. In preschool boys, shyness is more strongly associated with blue eyes than with brown eyes, but this association is absent in preschool girls (Coplan et al., 1997).
An 8,000 year-old hunter-gatherer from Luxembourg
The latest estimates place the whitening of European skin between 19,000 and 11,000 years ago (Beleza et al., 2013). We have no estimates at all for the diversification of European hair color. For diversification of European eye color, we used to have only an educated guess of 6,000 to 10,000 years ago (Eiberg et al., 2008).
A recent study has pushed the origin of blue eyes farther back in time. When ancient DNA was retrieved from the remains of a hunter-gatherer who lived 8,000 years ago in present-day Luxembourg, the reconstituted genome revealed that this individual probably had blue eyes (Lazaridis et al., 2013).
This finding shows that blue eyes already existed when early Europeans were still hunter-gatherers. It thus undermines a rival theory that Gregory Cochran put forward to explain the diverse palette of European hair and eye colors.
Greg’s theory is a mirror image of my own. I argue that shyness in blue-eyed boys is a side effect of sexual selection for women with novel hair and eye colors (Frost, 2006; Frost, 2008). He argues that these new colors are a side effect of natural selection for male submissiveness. This alternate theory is presented in The 10,000 Year Explosion:
[...] selection on genes affecting skin color, eye color, and hair color somehow created lots of variety in Europeans: redheads and blondes, blue eyes and green eyes. Nowhere else in the world is that sort of variety common. In most parts of the world, even in temperate regions, everyone has dark eyes and dark hair. (Cochran and Harpending, 2009, p. 94)
With the introduction of farming to Europe, and a resulting rise in population density and sedentary living, people had to become more socially wary. This self-domestication thus favored blue eyes (and presumably other eye and hair colors) as an evolutionary side effect:
Selection for submission to authority sounds unnervingly like domestication. In fact, there are parallels between the domestication in animals and the changes that have occurred in humans during the Holocene period. In both humans and domesticated animals, we see a reduction in brain size, broader skulls, changes in hair color or coat color, and smaller teeth. (Cochran and Harpending, 2009, p. 112)
Can this theory accommodate the recent discovery of a blue-eyed hunter-gatherer? One might argue that this individual was a fluke, perhaps a result of gene flow from farming communities. To settle this debate, we really need ancient DNA from pre-Holocene Europe, particularly from the critical period of 10,000 to 20,000 BP.
My ebook collection
I've decided to begin writing a collection of ebooks on subjects that have come up several times on this blog. This is partly in response to requests from different people and partly because I feel I should be exploiting this niche.
For now, I am trying to educate myself about the mechanics of it all. PDF seems to be the best format but consumes a lot of space. There is also the question of whether I should self-publish or go through a publishing house. Getting published, especially in the English-language market, inevitably means finding a literary agent and tolerating a lot of questionable schmoozing, not to mention delays.
Why the minimum wage matters (even on an anthropology blog)
I've never understood why conservatives are so hostile to a higher minimum wage. At present, minimum wage earners take more from the public purse than they put back in. They are tax consumers, not tax payers. As a result, the taxpayer is subsidizing employers who cannot or will not pay a wage that is at least fiscally neutral.
This situation is especially toxic at a time when the business community is seeking to cut labor costs through globalization. If a job cannot be outsourced, as is often the case with employment in services, construction, and food processing, the answer is to “insource” labor at a lower rate of pay ... with the costs of public services being passed on to a shrinking base of taxpayers.
The irony of it all is pointed out by Ron Unz:
The most doctrinaire libertarians, notably Prof. Bryan Caplan of George Mason University, have held fast to their principles and denounced the very notion of a minimum wage as a violation of basic human liberty. If a desperately impoverished Congolese is willing to come to America and work for a dollar a day, then that is his fundamental moral right, at least if he is willing to forego any access to medical care or other normal social benefits as part of the deal. (Unz, 2013)
That part of the deal won't be happening any time soon. Perhaps libertarians know this but think they can bankrupt the welfare state through mass immigration. Or perhaps they haven’t thought this idea all the way through. Or perhaps they're just shills.
Hostility to the minimum wage isn’t just a libertarian thing. Mainstream conservatives feel the same way:
Harvard economist and former Reagan Advisor Martin Feldstein recently took to the editorial pages of The Wall Street Journal to explicitly call for the creation of a new economic system that would fully integrate welfare payments and work into a seamless system of government support aimed at ensuring a basic standard of living for everyone in the country.
[...] Indeed, Feldstein argued that once the eligibility of various welfare programs were widened, the minimum wage could reasonably be cut, allowing American workers to take jobs paying just four, five or six dollars per hour, with the ordinary taxpayer making up the difference. The logical endpoint to such proposals would be for businesses to pay their workers absolutely nothing at all, with all employee living expenses and spending money coming from governmental anti-poverty programs. (Unz, 2013)
This kind of income support (earned income tax credit) already exists and cost the American taxpayer $56 billion in 2012. Feldstein’s proposal would not only expand it but also extend it to a range of wages that is currently illegal and found only outside the Western world. It would thus greatly facilitate the ongoing influx of low-wage labor.
Not such a great idea
When the concept of "globalization" first became popular, we were told it would create so much more wealth that we would all be better off. The reality has been less wonderful. Median wages have stagnated throughout the Western world since the mid-1970s, despite a doubling of worker productivity. And the trend is now downwards. In a globalized world where businesses can move about capital and labor as they please, there is nothing to stop our wages from being leveled down to the current global mean.
And that's the best scenario. By dissolving those cultures that have historically produced the most wealth—because of their peaceful social relations, future time orientation, and high level of trust—globalization may cause an overall contraction of economic activity. History will go into reverse. We will lose the market economy and return to the old marketplace economy, where most monetary transactions take place in gated high-security enclosures.
References
Beleza, S., Murias dos Santos, A., McEvoy, B., Alves, I., Martinho, C., Cameron, E., Shriver, M.D., Parra E.J., and Rocha, J. (2013). The timing of pigmentation lightening in Europeans. Molecular Biology and Evolution, 30, 24-35.
http://mbe.oxfordjournals.org/content/30/1/24.shortCochran, G.M. and H. Harpending. (2009). The 10,000 Year Explosion, Basic Books.
Coplan, R., B. Coleman, and K. Rubin. (1998). Shyness and little boy blue: Iris pigmentation, gender, and social wariness in preschoolers. Developmental Psychobiology, 32, 37-44.
Edwards, E.A., and Duntley, S.Q. (1939). The pigments and color of living human skin. American Journal of Anatomy, 65, 1-33.
Edwards, E.A., and Duntley, S.Q. (1949). Cutaneous vascular changes in women in reference to the menstrual cycle and ovariectomy. American Journal of Obstetrics & Gynecology, 57, 501-509.
Edwards, E.A., Hamilton, J.B., Duntley, S.Q., and Hubert, G. (1941). Cutaneous vascular and pigmentary changes in castrate and eunuchoid men. Endocrinology, 28, 119-128.
Eiberg, H., Troelsen, J., Nielsen, M., Mikkelsen, A., Mengel-From, J., Kjaer, K.W., and Hansen, L. (2008). Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression. Human Genetics, 123, 177-187.
Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103.
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.pdfLazaridis, I., Patterson, N., Mittnik, A., Renaud, G., Mallick, S., et al. (2013). Ancient human genomes suggest three ancestral populations for present-day Europeans, BioRxiv, December 23.
http://biorxiv.org/content/early/2013/12/23/001552.full-text.pdf+htmlKleisner, K., Kocnar, T., Rubešova, A., and Flegr, J. (2010). Eye color predicts but does not directly influence perceived dominance in men. Personality and Individual Differences, 49, 59-64.
Kleisner, K., Priplatova, L., Frost, P., and Flegr, J. (2013). Trustworthy-looking face meets brown eyes. PLoS One, 8(1): e53285.
Liberton, D.K., Matthes, K.A., Pereira, R., Frudakis, T., Puts, D.A., & Shriver, M.D. (2009). Patterns of correlation between genetic ancestry and facial features suggest selection on females is driving differentiation, Poster #326. American Society of Human Genetics, 59th annual meeting, October 20-24, 2009. Honolulu, Hawaii.
Manning, J.T., Bundred, P.E., and Mather, F.M. (2004). Second to fourth digit ratio, sexual selection, and skin colour. Evolution and Human Behavior, 25, 38-50.
Martinez-Cadenas, C., Pena-Chilet, M., Ibarrola-Villava, M., & Ribas, G. (2013). Gender is a major factor explaining discrepancies in eye colour prediction based on HERC2/OCA2 genotype and the IrisPlex model. Forensic Science International: Genetics, 7, 453-460.
Mazess, R.B. (1967). Skin color in Bahamian Negroes. Human Biology, 39, 145-154.
Shekar, S.N., Duffy, D.L., Frudakis, T., Montgomery, G.W., James, M.R., Sturm, R.A., and Martin, N.G. (2008). Spectrophotometric methods for quantifying pigmentation in human hair-Influence of MC1R genotype and environment. Photochemistry and Photobiology, 84, 719-726.
Unz, R. (2013). Conservatives for more welfare, The Unz Review, December 30.
http://www.unz.com/runz/conservatives-for-more-welfare/van den Berghe, P.L., and Frost, P. (1986). Skin color preference, sexual dimorphism and sexual selection: A case of gene-culture co-evolution? Ethnic and Racial Studies, 9, 87-113.