The distinguishing physical
features of Europeans began as female features.
I’ve published a book through
Academica Press. It’s titled: European
Hair, Eye, and Skin Color: Solving the Puzzle. It can be ordered at: https://www.academicapress.com/node/549
Here is a summary:
Europeans are strangely
colored, particularly in the north and east. Hair is not only black but also
brown, flaxen, golden, or red. Eyes are not only brown but also blue, gray,
hazel, or green. Finally, skin is white, almost like that of an albino.
That color scheme is strange
for several reasons:
·
It arose through new alleles at unrelated genes: hair color diversified through a proliferation of
new alleles at MC1R, and eye color
through a proliferation of new alleles in the HERC2-OCA2 region. Skin color became fair through new alleles at SLC45A2, SLC24A5, and TYRP1. All
three changes occurred in parallel at different loci on the genome.
· The new hair and eye color alleles are too numerous and too recent to be due to anything but strong selection. Among Europeans, the various hair colors are produced by new alleles at over 200 loci (SNPs), and the various eye colors by new alleles at over 124. Those alleles arose over a relatively short span of time, certainly less than the 50,000 years that modern humans have been in Europe. Only some kind of selection, and very strong selection at that, could have caused such a proliferation of new alleles over such a short time.
·
The selection was aimed primarily at women. Even today, women naturally have a higher incidence
of red hair, blonde hair, and green eyes. Hair and eye colors are more evenly
distributed among women: the less frequent colors are more common, and the more
frequent ones less common. Skin is also fairer in women.
·
The new colors are mostly on or near the face, the focus of
visual attention. When compared with the original black and brown, they are brighter and “purer” (they occupy
thinner slices of the visible spectrum). Brightness and purity are
characteristic of colors favored by sexual selection. A third characteristic is
novelty: the relative rarity of a color. Novelty improves mating success by
attracting attention and interest, but that success is eventually its undoing.
As each generation passes, it becomes more common and less novel. Other colors attract
more interest, particularly new ones that arise through mutation, with the
result that a growing number of color variants accumulate in the gene pool.
Such color polymorphisms are a frequent outcome of sexual selection.
·
Unlike the hair and the eyes, the skin did not develop
a color polymorphism among Europeans, instead becoming unusually pale. The reason may be that sexual selection was guided
by a pre-existing dimorphism. In all populations, men are browner and ruddier
than women, who by comparison are fairer. Fairer-skinned women were seen as
more feminine in traditional cultures and preferred as mates. Sexual selection,
if sufficiently strong, would have drained the European gene pool of alleles
for dark skin.
Sexual selection is not the
preferred explanation among writers on this subject. Most lean toward one of
two scenarios that involve natural selection:
·
Relaxation of selection for dark skin: when modern humans entered Europe, natural selection
stopped favoring dark skin because UV protection was less necessary at northern
latitudes. Defective alleles for skin pigmentation began to accumulate in the
gene pool, and some of them had effects on hair and eye color.
That scenario has two weak points:
o
Relaxation of
selection would take more than a million years to produce the current diversity
of hair and eye colors. Yet modern humans have been in Europe for only 50,000
years. In fact, it was only around 20,000 years ago that some Europeans began
to acquire pale skin and diverse hair and eye colors, and that phenotype would not
become fully established throughout Europe until 10,000 to 5,000 years ago.
o
Skin color is
weakly linked to hair color and eye color. Light skin often coexists with dark
hair and dark eyes.
·
Selection for light skin: natural selection reduced skin pigmentation in order to maintain
sufficient production of vitamin D. The hair and the eyes underwent a similar
reduction in pigmentation because a change to one pigmentary trait presumably affects
the others.
That scenario has two weak points:
o
Again, skin color
is weakly linked to hair color and eye color. Yet the changes to the latter
have been as profound as those to skin color. Moreover, the changes to hair and
eye color have not been so much a reduction in pigmentation as a non-random
creation of new hues that emit more light within narrower slices of the spectrum.
o
Analysis of ancient
DNA and present-day DNA indicates that modern humans were dark-skinned for tens
of thousands of years after their entry into Europe. Why wasn’t vitamin D a
problem then? If we consider the indigenous inhabitants of North and South
America, we see that natural selection has created very little latitudinal
variation in their skin color, even though they have lived in the Americas for
some 12,000 years. Natural selection, by itself, appears to change skin color
rather slowly.
The current physical features of Europeans seem to have arisen on the steppe-tundra of eastern Europe and western Siberia during the last ice age, between 10,000 and 20,000 years ago, when nomadic humans subsisted almost entirely on meat from reindeer and other migratory game. Long-distance hunting increased the death rate among men and decreased the polygyny rate—only the ablest hunters could provide for more than one woman and her children because women had almost no food autonomy.
The
result: a surplus of women on the mate market; intense rivalry among them for
male attention; and strong selection for eye-catching female features. Such
features became more frequent with succeeding generations, eventually forming
what is now seen as the “European” phenotype.
Frost, P. (2022). European Hair, Eye, and Skin Color: Solving
the Puzzle. Washington: Academica Press, 169 pp., hardcover, ISBN
9781680538724
If you wish to buy a less
expensive paperback edition, please make your preference known to Academica
Press by emailing to:
academicapress.editorial@gmail.com
16 comments:
It would have been interesting if said female surplus occurred in the tropics more often. Would there have been darker skin. But brightly colored hair and eyes?
What is your explanation for the light skin color of East Asians?
Peter, do you know if there will be a lower-priced paperback edition of your new book? As an amateur enthusiast I find your work quite fascinating but the academic press book pricing is rather steep for individuals. Thanks, and thanks for all the work you put in to this blog.
High lattitudes. Did you even read the words, or use your brain?
nice work Peter.
golazo!
Anon,
Fair hair does occur among the indigenous inhabitants of Australia and Melanesia. In Central Australia, the incidence is 85% for both sexes up to ten years of age. Male hair then darkens, its color ranging from medium brown to black during adolescence and being almost always dark beyond the age of twenty. In contrast, female hair darkens only after twenty and is seldom darker than light brown even in old age.
So this might be due to a similar selection pressure that is aimed both at women and at children. I discuss this possibility in the book.
Jb,
It looks like the "epicenter" of sexual selection was in eastern Europe and parts of Siberia during the last ice age. Lightening of skin color may have taken place over a wider geographic area, as seems to have been the case with straightening and lengthening of head hair. The latter evolutionary changes may have required a lower threshold of sexual selection (in comparison to diversification of hair and eye color).
Sirius,
Please send an email to Academica Press (academicapress.editorial@gmail.com) and tell them what you told me. I argued with the editor over the pricing, making the same points you made. He was confident that the book could be sold as a hardcover at that price.
https://www.psypost.org/2022/10/a-common-parasitic-disease-called-toxoplasmosis-might-alter-a-persons-political-beliefs-63999
I already said I wouldn't comment here anymore, but this study excited me to go back just to post and conclude that any study on parasites and human behavior and their results always seems so random...
On the subject of the text.
Scandinavians are the blondest, but have the fewest redheads. Redheads appear more often where there are lighter brunettes. The British have more redheads and light brunnettes [Norwegians have a middle ground pattern between Brits and Scandinavians] and is lighter skin too, of course, before the invasion.
Santocool,
I suspect that toxoplasma breaks down social and cultural inhibitions. A half-century ago, such "dis-inhibited" individuals would have become radical Marxists. Today, they become radical traditionalists.
We need more research on Candida species and their behavioral effects.
The reason I asked about East Asians is that the alleles responsible for their light skin are different from those responsible for light skin in Europeans. It sounds like you are saying that lightening of skin was a process that happened independently in Europe and East Asia, while sexual selection for hair and eye color was a different process that happened only in Europe. Do I have that right?
Also, how well do we understand hair form? It seems to me that, with the possible exception of some Melanesians, "kinky hair" is unique to sub-Saharan Africans, and sharply differentiates them phenotypically from the rest of the world, certainly more so than skin color. Yet I've seen very little discussion of what would appear to be a highly informative trait in terms of understanding the history of the deepest genetic division of the human race.
For example, if the earliest Europeans did not have kinky hair that would suggest to me that maybe there is something to Dienekes' idea that the ancestors of modern non-Africans were separated from those of modern sub-Saharans for a very long time, perhaps in Arabia, before moving on to the rest of the world, and that hair straightening, and possibly other changes, could have taken place there. Anyway, do you have any thoughts on this?
Jb,
Europeans became more and more reproductively isolated from North Asians with the onset of the glacial maximum (about 17 thousand years ago). This relative reproductive isolation continued into the Mesolithic and the Neolithic as populations became larger, less nomadic, and more fixed within smaller territories. Selection for light skin in present-day North Asians took place largely after the glacial maximum, if only because there had been widespread extinction of North Asian populations at the glacial maximum.
I believe that selection for new hair and eye colors took place during the first half of the ice age (before the glacial maximum) within the steppe-tundra stretching from the Baltic to central Siberia. Blonde hair has been dated to 18,000 years ago, according to ancient DNA retrieved from a site in central Siberia.
As for hair form, here is a cut-and-paste from the book:
1. In a population ancestral to Europeans and East Asians, hair became thick, straight, and long some 30,000 years ago via a derived allele at the EDAR gene.
2. Those ancestral Eurasians split into two groups: a western group that would become present-day Europeans and an eastern group that would become present-day East Asians.
3. Thick straight hair remained prevalent in the eastern group but disappeared in the western group. Nonetheless, it was still present in half of Europeans as late as 8,000 years ago, according to ancient DNA from Motala, Sweden. Today, its incidence is 87% in East Asians and about 1% in Europeans.
4. Europeans thus went from thick straight hair to thin hair with diverse forms: about 45% now have straight hair, about 40% wavy hair, and about 15% curly hair. Curly hair is thus a derived trait among Europeans and not a holdover from ancestral Africans. Hair form became diverse in Europeans probably for the same reason that hair and eye color did—a desire for novelty. Indeed, an Austrian study has shown that women tend to change their hair form to a less common
''Santocool,
I suspect that toxoplasma breaks down social and cultural inhibitions. A half-century ago, such "dis-inhibited" individuals would have become radical Marxists. Today, they become radical traditionalists.
We need more research on Candida species and their behavioral effects.''
I have a lot of reservations about parasites altering human behavior. I understand that this can happen with other species. But the human species is too complex. Even if there is an interaction, I don't believe the results are so dramatic, that the effect can be more localized.
Remember that any such study finds correlations. This means that not all study individuals who tested positive for "toxoplasma infection" showed the same political-ideological tendencies.
I think Caucasians are bizarrely different from other human populations, so the selection of distinctive facial patterns generally found in this group may have come first. But of course I have no evidence of that.
After all, do typically Caucasian facial features have any relationship to clear complexion??
It is also important to clarify about “the inhabitants of Europe had dark skin”. People imagine a black African male, but it is possible/likely that he was a human with more tanned skin, and more Caucasian features, based on the hypothesis that facial features were selected first.
3. Thick straight hair remained prevalent in the eastern group but disappeared in the western group. Nonetheless, it was still present in half of Europeans as late as 8,000 years ago, according to ancient DNA from Motala, Sweden. Today, its incidence is 87% in East Asians and about 1% in Europeans.
If by "Europeans" we mean the modern populations derived from some composite of hunter-gatherers/Indo-Europeans/EEFs, then those in Motala, Sweden 8,000 years ago would have been a different group, no? Perhaps analogous to the Amerindians who were largely replaced in North America.
I think Caucasians are bizarrely different from other human populations, so the selection of distinctive facial patterns generally found in this group may have come first. But of course I have no evidence of that.
After all, do typically Caucasian facial features have any relationship to clear complexion??
It is also important to clarify about “the inhabitants of Europe had dark skin”. People imagine a black African male, but it is possible/likely that he was a human with more tanned skin, and more Caucasian features, based on the hypothesis that facial features were selected first.
Peter does specify "European", which is a subset of "Caucasian", a more general category that also includes populations that are mainly dark haired/eyed with olive or dark complexions.
There are examples of people in the Middle East and South Asia who have dark skin with Caucasian features.
Peter,
I have emailed Academic Press as you suggested, inquiring about a lower-priced paperback edition that would be more affordable for amateur enthusiasts. Thanks.
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