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« A Weird Phenomenon | Main | Blondes Not Going Extinct »

February 27, 2006

Comments

dsquared

[Almost the only sustenance in northern Europe came from roaming herds of mammoths, reindeer, bison and horses]

yes, yes, fish and birds only evolved later or something.

is it not more likely that the gene for "not much pigment in the hair" is mixed up with the gene for "not much pigment in the skin" in some ill-defined sense in the space of possible genomes, and we know why the "not much pigment in the skin" gene caught on, because it's to do with the relative dangerousness of sunburn and vitamin D deficiency in places like Galashiels.

I also don't agree that the fact something evolved in a small number of generations is evidence of sexual selection.

Gdr

The bulk of the Times article appears to be a reasonably accurate summary of the abstract of Peter Frost's article "European hair and eye color: A case of frequency-dependent sexual selection?", to be published in the March 2006 issue of "Evolution and Human Behavior". (Apart from the focus on blondes and blue eyes; Frost only talks about variation in hair and eye colour.)

It could be a reasonable paper or it could be a silly piece of just-so speculation, but I haven't read it so I'm not going to dismiss it as junk science quite yet.

Gdr

More of Peter Frost's work, on skin colour differences, at http://pages.globetrotter.net/peter_frost61z/

Andrew

Particularly egregious is the use of the phrasing "new research has found" when this paper is not a new empirical study but an argument based on existing evidence (such as it is).

I can't get access to the article either; but the abstract does not exactly bode well:

[Human hair and eye color is unusually diverse in northern and eastern Europe. The many alleles involved (at least seven for hair color) and their independent origin over a short span of evolutionary time indicate some kind of selection. Sexual selection is particularly indicated because it is known to favor color traits and color polymorphisms. In addition, hair and eye color is most diverse in what used to be, when first peopled by hunter-gatherers, a unique ecozone of low-latitude continental tundra. This type of environment skews the operational sex ratio (OSR) of hunter-gatherers toward a male shortage in two ways: (1) men have to hunt highly mobile and spatially concentrated herbivores over longer distances, with no alternate food sources in case of failure, the result being more deaths among young men; (2) women have fewer opportunities for food gathering and thus require more male provisioning, the result being less polygyny. These two factors combine to leave more women than men unmated at any one time. Such an OSR imbalance would have increased the pressures of sexual selection on early European women, one possible outcome being an unusual complex of color traits: hair- and eye-c olor diversity and, possibly, extreme skin depigmentation.]

Abiola

"I haven't read it so I'm not going to dismiss it as junk science quite yet."

I don't need to read anything to know it's junk: if Frost's theory is true, where are the blonde Eskimos?

Gdr

If I read the abstract correctly, Frost wouldn't predict blonde Inuit, but rather that Inuit women vary more in colour than related groups of people do. Of course, he would also predict that the effect would be smaller than for Europeans since the Inuit have had less time for the variation to arise. (I'm ignorant about colour variation in Inuit women, so I can't say if his predictions are supported, sorry.) Note also that we wouldn't expect Inuit to have white skin, since fish liver is an excellent source of vitamin D.

Gdr

This idea is far from original to Frost, by the way. Darwin wrote in "The Descent of Man" (1871):

"the differences between the races of man, as in colour, hairiness, form of features, etc., are of a kind which might have been expected to come under the influence of sexual selection".

Chuckles

Blondes originated in Europe and are going extinct?

Well, I guess these people:

http://www.afrikaansealbinos.nl/Doc/leaflet.pdf

http://www.pieterhugo.com/albino/04.html

dont count.

So much for sexual selection.

Gdr

Of course they don't count; they are African albinos, not blonde Europeans!

Ross

I not going to actually read the study so I can only appreciate the junk journalism rather than the possibly junk science.

{A study by the World Health Organisation found that natural blonds are likely to be extinct within 200 years because there are too few people carrying the blond gene.}

Anyone can fall for a hoax but you would have thought that writing an article simultaneously explaining that blondness is an advantageous evolutionary trait but that it is dying out ought to have rung alarm bells for the reporters, don't the Times have a Science Editor?

At least they have the good sense to ask the experts- "Jodie Kidd, 27, the blonde model, disagrees with the theory".

Ross

That should of course be "I am not" rather than "I not", I would like to claim that I was simply reverting to caveman speak but I'd be lying.

Chuckles

[...Of course they don't count; they are African albinos, not blonde Europeans...]

Ehhhh - From an evolutionary perspective; whats the difference between the 2 groups? qua difference in light of the traits under discussion?

Abiola

Blondness occurs in Australian Aboriginals too.

"Frost wouldn't predict blonde Inuit, but rather that Inuit women vary more in colour than related groups of people do."

Why the difference?

"Of course, he would also predict that the effect would be smaller than for Europeans since the Inuit have had less time for the variation to arise."

This is nonsense. The Inuit are descended from the very same migrant groups who populated north-east Asia and the Americas after splitting from the ancestors of modern Europeans.

"Note also that we wouldn't expect Inuit to have white skin, since fish liver is an excellent source of vitamin D."

In other words, we're sneaking in old fashioned positive selection for useful traits in order to rescue a "theory" which says sexual selection is what really counts ...

As I said, Frost's "theory" is clearly a load of armchair bunkum, even without the Times journalists' inane contributions. There's no need to "explain" blondness by resorting to fanciful descriptions of courtship and division of labor in long-dead societies which left no written records, especially seeing as we don't even yet have anything near full knowledge of just which genes underlie human skin and hair color variation.

"Anyone can fall for a hoax but you would have thought that writing an article simultaneously explaining that blondness is an advantageous evolutionary trait but that it is dying out ought to have rung alarm bells for the reporters"

Excellent catch! The report is a motherlode of inanities - it takes real effort to pack so much nonsense into such a short space.

Gdr

>>> Why the difference?

Frost's theory appears to be that hunters have a lower male:female ratio than hunter-gatherers; this leads to reproductive competition among women, which leads to greater variation in colour. His theory doesn't predict what the variation will consist of.

The correlation between operational sex ratio, sex selection, and variation is documented in other species of animals, it's not just a speculative theory.

>>> The Inuit are descended from the very same migrant groups who populated north-east Asia and the Americas

That's right, but Europeans have been living in high latitudes for 40,000 years or so; Inuit for 10,000 or less.

Abiola

"Europeans have been living in high latitudes for 40,000 years or so; Inuit for 10,000 or less"

This is ridiculous. Since when has North-East Asia been anything less than "high latitude"? When exactly do you think the first humans crossed into North America?

Gdr

>>> From an evolutionary perspective; whats the difference between the 2 groups? qua difference in light of the traits under discussion?

They are simply different populations with different alleles. There are several alleles found throughout the world that cause albinism; none of these is the same as the allele for white skin in Europeans.

You might want to read this article: http://www.washingtonpost.com/wp-dyn/content/article/2005/12/15/AR2005121501728_pf.html which reports on Lamason et al ("SLC24A5, a Putative Cation Exchanger, Affects Pigmentation in Zebrafish and Humans", Science, 16 December 2005).

Gdr

>>> When exactly do you think the first humans crossed into North America?

About 15,000 years ago. But Inuit aren't descended from the first group to cross into North America; they are a later migration.

Chuckles

[...They are simply different populations with different alleles. There are several alleles found throughout the world that cause albinism; none of these is the same as the allele for white skin in Europeans...]

So? Is blondeness a phenotypic trait or an allele? When sexual selection supposedly occurs, does it occur because individuals *know* certain alleles are present, or does it occur because certain traits have been manifest? You obviously dont have a solid handle on this topic.

But again, to humor you; OCA2 (P gene) mutations are indicated in albinism in African populations - and have been hypothetically correlated to various European phenotypes. So the different populations with different alleles doesnt work here.

Furthermore *you* dont know what your so called "allele" for white skin in Europeans (as though there were one) is - so how can you claim that what causes albinism in Africans has nothing to do with white skins in Europeans?

The simple fact of the matter is that several genes are implicated in skin color - but contemporary hypotheses of sexual selection are ultimately be concerned with phenotypic manifestations. In that sense; it becomes irrelevant who, what, how or where albinos in Africa become albinos; or ghostly blondes in Europe become such.

Gdr

The question that Frost is speculating about is: why did white skin and blonde hair become widespread in Europeans but not in other populations? His answer is that sexual selection took place in Europe but not in Africa because of the lower male:female ratio among European hunters.

Albinism doesn't refute Frost's argument. It shows one way in which variation in skin colour can arise, but it doesn't explain why it became widespread in some populations and not others.

I don't want to defend Frost's argument, especially since I haven't read his paper. But it isn't obvious to me that it's rubbish: you need to work a bit harder to convince me that it is.

Abiola

"But Inuit aren't descended from the first group to cross into North America; they are a later migration."

From where, Polynesia? And what about the rest of the North-East Asian population, then, did they only get there within the last 10,000 years? Where did the ancestors of the first American settlers come from, exactly? And even granting your absurd dates, why is it that 10,000 years hasn't sufficed for blonde hair to show up at all in any East Asian populations whatsoever, seeing as Eurasian populations haven't been completely reproductively isolated during this period?

Either cough up some PubMed citations to back up your stuff or stop trying to pass off such rank nonsense as "fact." Foster's "theory" is a load of hand-waving nonsense.

Chuckles

[...His answer is that sexual selection took place in Europe but not in Africa because of the lower male:female ratio among European hunters...]

[...it doesn't explain why it became widespread in some populations and not others...]

No - this is what is said in the Times article:

[...rapid change as women struggled to evolve the most alluring qualities...]

There you have it stated, precisely, that Blondeness qua Blondeness is an alluring quality. Right? So, in the face of stiff competition, blondes win out in wintry Europe over Brunettes, and they get to mate with the Males and spread little Blonde children all over, right? So blondeness increases as a phenotypic trait in the population, right?

So tell me: How come this only holds for Europe? Even assuming that competition wasnt that stiff in Africa: Where are all the fellas jumping over phenotypic blondeness in Africa and Australia (doesnt matter whether they are albinos or not)?

In order for sexual selectionists to resolve this connundrum; they introduce positive selection for clearly biochemically useful traits and slip in sexual selection for ornate traits as a bonus.

Look, the bottom line is clear: Our caveman brethren werent lusting over blondes for their alluring qualities to an extent that informs the presence of blondeness in Europe today.

The question you have to answer is: Just why would a caveman choose a blonde out of a pool of 30 girls, the rest of them non-blondes?

Abiola

Indeed, why would any macho man hunter have to (let alone want to) *choose* at all? It's not as if a man can only impregnate a single woman at a time - just ask any number of satisfied male customers of the Religion of Peace - so why would female sexual selection even matter if men were in such short supply? Is there a straight man alive who *hasn't* fantasized about having masses of women pleading for his attention, blonde or otherwise?

From a common-sense experience angle the whole thing seems even more ridiculous. We're supposed to buy that blondeness somehow boosts sexual attractiveness in an objective fashion, and yet not only are the most populous "race" - the peoples of northeast Asia - anything *but* blonde-haired haired or blue-eyed, but the black-haired, brown-eyed women of this very same region seem to hold an irresistable allure for too many white males to count, despite the presence of supposedly more attractive blondes much closer at hand; white women working in Singapore, Seoul or Tokyo don't exactly get to thrive on the attention of their compatriots, blonde hair notwithstanding, and last I looked, I didn't see too many men whining for BSG's Grace Park to be replaced by a Paris Hilton clone ...

The closer you look at this "theory", the more holes it develops, like Havarti cheese ripening in a cellar.

Gdr

>>> From where, Polynesia?

No, they are thought to be from Mongolia. See for example http://www3.interscience.wiley.com/cgi-bin/abstract/28223/ABSTRACT

>>> And what about the rest of the North-East Asian population?

There are archaeological remains from Siberia that go back 30,000 years. But the Inuit and related peoples entered the arctic much more recently; see for example http://www.sas.upenn.edu/~tgschurr/pdf/Schurr%202004%20ARA.pdf which dates their origin to 13,120–10,000 years ago.

Abiola

"No, they are thought to be from Mongolia."

1 - That research paper is incredibly old, considering how much DNA-based research has subsequently been done on this topic.

2 - Leaving aside its age, have you looked at the latitude of Mongolia on a map lately? You aren't exactly solidifying your claims here.

"But the Inuit and related peoples entered the arctic much more recently"

For every such paper you dig up, I can unearth many others like the following:

http://tinyurl.com/h5lnu

["Basing on the frequencies of 28 alleles of 12 polymorphic loci of blood groups, serum proteins and red cell enzymes the matrix of genetic distances between 11 populations of Europe, Asia and America was calculated. This matrix and the dendrogram based on it permitted to suggest that the region of South Siberia and the neighbouring regions of Central Asia was the place, where the paleolithic populations were divided into the ancestors of the Northern Mongoloids, Caucasoids and American Indians. The published data concerning the human mtDNA polymorphisms support the hypothesis of the author."]

http://tinyurl.com/zxxex

["In search of the ancestors of Native American mitochondrial DNA (mtDNA) haplogroups, we analyzed the mtDNA of 531 individuals from nine indigenous populations in Siberia ... Overall, our data suggest that the immediate ancestors of the Siberian/Beringian migrants who gave rise to ancient (pre-Clovis) Paleoindians have a common origin with aboriginal people of the area now designated the Altai-Sayan Upland, as well as the Lower Amur/Sea of Okhotsk region."]

In any case, you still haven't explained why 10,000 years wouldn't suffice for genes for blondness to have reached a high enough frequency that at least 1 in 200 East Asian women aren't blondes by now, or why they seem to be more than holding their own in the sexual attractiveness stakes next to the blondes we're all supposed to prefer.

Gdr

>>> Where are all the fellas jumping over phenotypic blondeness in Africa and Australia?

I don't know. But even if they existed, they wouldn't lead to the spread of blondeness and white skin in these countries because the increased sexual attraction would be balanced by the increased risk of skin cancer. The outcome would be a balance between natural selection and sexual selection. See for example http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12573076&dopt=Abstract

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