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
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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.short
Cochran, 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.
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populations for present-day Europeans, BioRxiv,
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