Getting noticed

"A rapid and effective means for getting noticed in the crowd." Lady Gaga(?) in Stylist France.

I'm back to blogging after a 3-month absence. During my hiatus the magazine Stylist France interviewed me about head hair as a form of advertising. The resulting article appeared on October 11 under the headline "Forget the slogan T-shirt. To get yourself heard, nothing is more effective than a new hairstyle."

The full interview, in French with an English translation, is provided below:

French version:

Pouvez-vous expliquer succinctement le rôle de la sélection sexuelle dans l'apparition des cheveux blonds ?

La sélection sexuelle favorise la brillance et la nouveauté. Ce qui est brillant demeure plus longtemps en mémoire; ce qui est nouveau retient plus longtemps l'attention. Si on considère les couleurs des cheveux et des yeux, on constate une évolution vers la brillance, c'est-à-dire les cheveux noirs et les yeux bruns cèdent leur place à des couleurs vives, comme les cheveux roux ou blonds et les yeux verts ou bleus.

Quant à l'évolution vers la nouveauté, celle-ci se manifeste par la diversification de la palette des cheveux et des yeux. Au début, une nouvelle couleur émerge par la mutation, puis elle se répand jusqu'à ce qu'elle perde sa nouveauté ; à ce moment-là, la pression de la sélection sexuelle se réoriente pour favoriser une couleur moins fréquente. Ainsi, un équilibre s'établit entre les diverses couleurs.

Qu'est-ce qui permet d'affirmer que la sélection sexuelle est aussi importante voire plus importante que les rayons UV dans l'apparition des cheveux blonds ?

D'abord, les gènes contrôlant la couleur de la peau et celle des cheveux ne sont pas les mêmes. On peut avoir la peau très blanche, tout en possédant les cheveux foncés. De plus, la pression de sélection exercée par les rayons UV n'explique pas la diversification des allèles contrôlant la couleur des cheveux et des yeux. Enfin, on ne voit pas cette diversification chez les peoples indigènes habitant les mêmes latitudes de l'Asie du Nord et de l'Amérique du Nord.

Vous affirmez que ces traits distinguant les Européens sur le plan visuel résultent d'une pression de sélection qui vise surtout la femme. Pourquoi pas l'homme ?

Il y a eu une pénurie d'hommes chez les premiers Européens, en partie parce que la dépendance de la viande, comme partie dominante de l'alimentation, rendait la polygamie trop coûteuse pour les hommes, sauf pour les meilleurs chasseurs. De plus, comme on le constate toujours chez les peoples chasseurs du Nord, le taux de mortalité est plus élevé chez les hommes que chez les femmes. Résultat : un surplus de femmes. Celles-ci devaient se concurrencer pour les hommes disponibles.

Finalement, il semble y avoir un parallèle fort entre la supposée attraction, aujourd'hui, des hommes pour les femmes blondes (et les stéréotypes et exemples qui en ont découlé dans la pop culture) et le phénomène d'apparition des cheveux blonds il y a 11.000 ans.

Aujourd'hui, grâce aux études de l'ADN extraits des restes humains, on sait que les cheveux blonds existaient déjà il y a 18 000 ans. Le lieu d'origine semble être chez les peoples chasseurs des plaines de l'Europe de l'est et de la Sibérie de l'ouest pendant la dernière glaciation.

English version:

Can you succinctly explain the role of sexual selection in the appearance of blond hair?

Sexual selection favors brightness and novelty. Anything bright remains longer in memory; anything novel holds attention longer. If we consider hair and eye colors, we see an evolution toward brightness, i.e., black hair and brown eyes have ceded their place to bright colors, like red or blond hair and green or blue eyes.

As for evolution toward novelty, this has manifested itself in a diversification of the palette for the hair and the eyes. Initially, a new color emerges through mutation; then it spreads until it loses its novelty; at that moment, the pressure of sexual selection reorients itself to favor a less frequent color. Thus, an equilibrium becomes established between the various colors.

What makes you think that sexual selection is as important, indeed more important, than UV radiation in the appearance of blond hair?

First, the genes controlling skin color and hair color are not the same. One can have very white skin while having dark hair. In addition, the selection pressure of UV radiation does not explain the diversification of alleles controlling hair and eye color. Finally, this diversification is not seen among indigenous peoples inhabiting the same latitudes of northern Asia and North America.

You affirm that these traits that visually distinguish Europeans result from a selection pressure that is aimed especially at women. Why not men?

There was a shortage of men among the first Europeans, partly because dependence on meat, as a dominant part of the diet, made polygamy too costly for men, except for the best hunters. In addition, as is still seen among northern hunting peoples, the mortality rate is higher among men than among women. Result: a surplus of women. Those women had to compete for the available men.

Finally, there seems to be a strong parallel between the purported attraction, today, of men for blonde women (and the resulting stereotypes and examples in pop culture) and the phenomenon of the appearance of blond hair 11,000 years ago.

Today, thanks to studies of DNA extracted from human remains, we know that blond hair already existed 18,000 years ago. The place of origin seems to be among the hunting peoples of the plains of eastern Europe and western Siberia during the last ice age.

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On rereading my answers I realize I may have misunderstood the last question. The intent seems to be:  “Given that these evolutionary processes happened thousands of years ago, how can they explain the growing popularity of blond hair today?” This intent became clearer to me when I read the article, which focuses on blondness in pop culture, and its apparent surge in popularity since the 1970s. 

This trend appears in a study of Playboy playmates from 1954 to 2007. From a low of about 35% in the mid-1960s the proportion of blonde playmates rose to a high of 60% by the year 2000 (Anon 2008). A similar trend was found by Rich and Cash (1993).

Natural blondes are actually a lot scarcer among white Americans. In a sample of undergraduates the proportions were 68% brown, 27% blond, and 5% red (Rich and Cash 1993). Similar proportions appear in a British study: 68% brown, 25% blond, 1% red, and 6% black (Takeda et al., 2006).

Natural blond hair has since become less common in the United States and the United Kingdom. Are we seeing the novelty effect in action? Are blondes becoming sexier because fewer real ones are out there?

References

Anon. (2008). Bygone brunette beauty: Fashion in hair color, Gene Expression June 29

www.gnxp.com/blog/2008/06/bygone-brunette-beauty-fashion-in-hair.php

D'Almeida, P. and M. Giuliani. (2018). Qu'elle a bien pu vouloir dire avec cette coupe ? Stylist France, October 11, pp. 2-5.

Rich, M.K., and T.F. Cash. (1993). The American image of beauty: Media representations of hair color for four decades. Sex Roles 29: 113-124.

Takeda, M.B., M.M. Helms, and N. Romanova. (2006). Hair color stereotyping and CEO selection in the United Kingdom. Journal of human behavior in the social environment 13: 85-99

A new allele for blond hair

 

Geographic prevalence of the new allele for blond hair (Guenther et al., 2014). Just one of many alleles that create the European palette of hair and eye colors.

 

There is a widespread belief that whatever made Europeans fair-skinned also gave them their unique palette of hair and eye colors. In reality, fair skin has only a weak genetic linkage with either non-black hair or non-brown eyes:

If we were to take all the human beings in the world who have dark brown eyes and black or dark brown hair, we would not only have the vast majority of the human species, but would have a group which shows virtually the complete range of human skin color, from black to almost completely depigmented. (Brues, 1975)

Hair color and eye color are largely uncoupled from skin color in our species—or rather in Europeans, to be more precise. It looks as if the pressure of selection has moved European color traits in different directions, on the one hand making the skin progressively lighter, and on the other making the hair and the eyes more and more diversely hued.

There have thus been different changes at different genes. European skin lightened mainly through the appearance of new alleles at three genes: SLC45A2, SLC24A5, and TYRP1. European hair color diversified through a proliferation of new alleles at MC1R. European eye color diversified through a proliferation of new alleles in the HERC2-OCA2 region and elsewhere.

In a recent study, Guenther et al. (2014) have shown that new alleles for European hair color proliferated not only at MC1R but also at other genes. In particular, blond hair seems to be due to an allele near KITLG, although other loci in this region seem involved as well. Thus, the diverse palette of European hair colors is not a side effect of a single genetic change. It is due to a proliferation of new alleles at many different places on the human genome. The only common element seems to be a selection pressure for more hair colors.

Guenther et al. (2014) likewise note that changes to hair color and eye color became uncoupled from changes to skin color in ancestral Europeans:

 

Some human pigmentation variants alter general aspects of pigment biosynthesis, producing changes in all melanocytes, and therefore have pleiotropic effects on hair, skin and eye color. However, it is well known that hair and eye color can also vary independently, producing common human phenotypes such as light-haired individuals with brown eyes or brown-haired individuals with blue eyes. The rs12821256 variant alters an enhancer that is active specifically in the hair follicle environment, providing a simple genetic explanation for previous observations that this SNP is associated with changes in hair pigmentation but not eye pigmentation in northern Europeans.

Why this uncoupling of European hair, eye, and skin color? These three color traits have probably undergone divergent selection pressures. Moreover, in all three cases the selection pressure seems to have acted primarily on women and only secondarily on men—an indication of some form of sexual selection where women were the sex in excess supply on the mate market (Frost, 2014). Because skin color is sexually dimorphic in all humans, with women being the "fair sex," this dimorphism may have biased sexual selection in the direction of increasingly lighter skin.  

Hair and eye color, however, had no preexistent sexual dimorphism. So sexual selection was driven simply by a desire for bright or novel colors. In other words, whenever a new color arose through mutation, it would have initially benefited from sexual selection. As it became more and more common in the population, this selection pressure would have gradually diminished until the new color had become as prevalent as other existing hues. As a result, the palette of hair and eye colors would have steadily grown larger and larger (Frost, 2006; Frost, 2014).

 

References

Brues, A.M. (1975). Rethinking human pigmentation, American Journal of Physical Anthropology, 43, 387-391.

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103. 

Frost, P. (2014). The puzzle of European hair, eye, and skin color, Advances in Anthropology, 4, 78-88.

http://www.scirp.org/journal/PaperInformation.aspx?PaperID=46104  

Guenther, C.A., B. Tasic, L. Luo, M.A. Bedell, and D.M. Kingsley. (2014). A molecular basis for classic blond hair color in Europeans, Nature Genetics, advance online

http://www.nature.com/ng/journal/vaop/ncurrent/full/ng.2991.html  

What makes hair color "hot"?

The ‘hot’ hair color this year (source). While there seems to be a general trend to prefer average physical characteristics, this doesn’t seem to apply to hair color. People seek colors that are uncommon or even unnatural.

Europeans have departed from the species norm of black hair and brown eyes by evolving a wide range of bright hair and eye colors. What is the selective advantage of these new hues? Or are they merely a side effect of something else?

I’ve argued that these new colors were selected for … their newness and colorfulness. To be precise, their selective advantage lay in their novelty and brightness. These eye-catching qualities enabled women to improve their mating prospects at a time when the operational sex ratio was skewed toward a female surplus and a male shortage.

This is the logic of advertising. Visual merchandising matters most in saturated, highly competitive markets that offer too many interesting choices (Lea-Greenwood, 1998; Oakley, 1990). Such a context rewards products that stand out because of their bright or novel look, as seen in colors for home interiors. This market has grown more competitive over the past half-century, and the novelty factor has correspondingly grown more important: preference for one paint color rises until satiated, then falls and yields to preference for another (Stansfield & Whitfield, 2005).

In the natural world, and under conditions of intense sexual selection, this same logic leads to a color polymorphism. A new color appears through mutation and spreads through the population until it is as common as the established color. This equilibrium will then last until another color variant appears. The total number of colors thus grows over time.

This aspect of sexual selection can be demonstrated under controlled conditions. In an American study, male participants were shown pictures of attractive brunettes and blondes and asked to choose, for each series, the woman they would most like to marry. One series had equal numbers of brunettes and blondes, a second series 1 brunette for every 5 blondes, and a third series 1 brunette for every 11 blondes. Result: the scarcer the brunettes were in a series, the likelier any one of them would be chosen (Thelen, 1983).

The same trend appears in popular culture. On American TV programs, women are four and a half times more likely than men to have red or auburn hair and five times more likely than men to have blonde hair. Conversely, men are four times more likely than women to have gray hair and 40% more likely than women to have black hair (Davis, 1990). A similar trend has been observed on Turkish TV programs:

Women were more likely than men to have red (5.3%) or blonde (15.6%) hair. In fact, no primary male characters in this sample had red or blonde hair at all, but female characters did. (Ikizler, 2007, p. 39)

This sex difference undoubtedly reflects the use of artificial hair coloring, although female hair color is naturally more diverse than male hair color (a legacy of the female-directed nature of sexual selection in Europe). Interestingly, women are using hair dyes to give themselves less typical hues, rather than more typical ones. Such colors may be uncommon but naturally occurring, such as platinum blonde and red. Or they may not exist at all in nature, such as green, purple, and magenta.

This year, the leading hair colors are forecasted to be “red, burgundy, strawberry blonde, copper brown and auburn shades.” Among celebrities, the hottest colors will include “bright reds, vibrant blues and pastel pinks” (Fall Hair Color Trends 2012).

References

Davis, M. D. (1990). Portrayals of women in prime-time network television: Some demographic characteristics. Sex Roles, 23(5/6), 325-332.

Fall Hair Color Trends 2012
http://researchanalyst.hubpages.com/hub/Hair-Color-Trends

Ikizler, A.S. (2007). Gender role representations in Turkish television programs, Submitted as a St. Mary's Project in Partial Fulfillment of the Graduation Requirements, St. Mary's College of Maryland for the Degree of Bachelor of Arts in Psychology
http://www.smcm.edu/psyc/_assets/documents/SMP/Showcase/0607-AIkizler.pdf

Lea-Greenwood G. (1998). Visual merchandising: a neglected area in UK fashion marketing? International Journal of Retail & Distribution Management, 26, 324-329.

Oakley M. (ed.) (1990). Design management. A handbook of issues and methods. Oxford: Basil Blackwell.

Stansfield J., & T.W.A. Whitfield. (2005). Can future colour trends be predicted on the basis of past colour trends? An empirical investigation. Color Research and Application, 30(3), 235-242.

Thelen, T.H. (1983). Minority type human mate preference. Social Biology, 30, 162-180.

Why are redheads less common than blondes?

Gilbert Blythe tormenting Anne Shirley (Anne of Green Gables)

Male preference for female hair color seems to be frequency-dependent. The less common a hair color becomes, the more it is preferred. When male subjects are presented with a series of photos showing blondes and brunettes, preference for any one brunette is inversely proportional to the number of brunettes in the series (Thelen, 1983). This frequency dependence may explain why blonde hair is less strongly preferred in England than in France.

England is, however, somewhat fairer generally than most parts of Europe; so that, while it may be said that a very beautiful woman in France or Spain may belong to the blondest section of the community, a very beautiful woman in England, even though of the same degree of blondness as her Continental sister, will not belong to the extremely blonde section of the English community. (Ellis, 2007[1905], p. 160)

Hair color is normally a minor factor when men select mates. It becomes a major factor only when the level of sexual selection is intense, like the situation of a movie producer who has to choose one actress from a number of excellent candidates. Under such conditions, relatively unimportant factors can make a big difference, especially those that can attract and retain attention.

I’ve argued that such conditions once prevailed among ancestral Europeans, specifically European women (Frost, 1994, 2006, 2008). One result was an ever broader range of eye and hair colors. Whenever a new color appeared through mutation, it would be favored by sexual selection until it had become as frequent as the other colors. Although the pressure of sexual selection was on women, these changes in physical appearance spilled over on to men, thereby creating a new phenotype in both sexes.

But we still see some evidence that this selection pressure had targeted women. A twin study has shown that hair is, on average, lighter-colored in women than in men, with red hair being especially more frequent in females. Women also show greater variation in hair color (Shekar et al., 2008).

Do redheads have less fun?

Red is the least common of these new hair colors. It also seems to have a lower tipping point where preference gives way to non-preference—if not dislike. Indeed, in comparison to blondes, redheads become more easily the butt of ridicule and prejudice.

How come? Several reasons appear in the literature. One is that Judas, the betrayer of Christ, was red-haired. Yet this association of ideas may have originated in a much older one that the Church later recycled for its own purposes:

There can be little doubt that this tradition is simply the application of the old belief—much older than Judas Iscariot—that red-haired men are treacherous and dangerous, to the Arch-traitor, sometime during the early Middle Ages, when the popular imagination was busy making up biographies and biographical details for the saints and martyrs of the Church. (Baum, 1922)

This older folk belief had its basis in the idea that redheads are hotheaded and not to be trusted:

We must look further for an explanation of Judas color, and specially in the ill-omen of red hair. This itself took its beginning no doubt, like so much else of popular tradition, in the shrewd observation of natural phenomena. The common German proverb, "Roter Bart, untreue Art," represents a condensed popular judgment. Even to-day a red-haired man is assumed to be hot-headed and quick-tempered, and so not quite to be counted on. (Baum, 1922)

Is this true? Perhaps. Of all the different hair colors, red is the one that seems to have the most pleiotropic effects, e.g., skin type, freckling, beard color, etc. (Flanagan et al., 2000). There are also physiological consequences. Redheads seem to be more sensitive to painkillers, the effect being stronger in women than in men (Mogil et al., 2003). This increased sensitivity was noted over sixty years ago:

Dr. Paul M. Wood, Secretary-Treasurer of the American Board of Anaesthesiology, writes, " ... in twenty-two years of personal experience I have discovered that many difficulties have occurred with persons who have red hair. They do not seem to take anaesthetics in the same way that others do. Most of them are much more sensitive to the anaesthetic."

Dr. David M. Levy states that red headed persons in general go under anaesthetic more readily than do persons of other pigmentations.

Dr. Marco Nunez confirms these observations that red heads are affected more readily than are other persons. (Keeler, 1947)

We may have here one reason why red hair never became as common as other hair colors. There were too many side effects, and natural selection has probably not had enough time to iron them all out.

But culture has probably been just as important in determining the frequency of red hair. Whereas attitudes to red hair tend to be negative in Latin cultures, they are generally positive in Celtic cultures, as Curry (1916, pp. 18-19) notes in his study of medieval literature: “It is worthy of note, however, that in the Old Irish and Welsh red hair seems to be appreciated, tho to a less extent than the blonde.”

The last point is interesting because the frequency of red hair is much higher in the Celtic regions of Europe (Wikipedia). Has this prevalence been maintained at a higher level by a more “redhead-friendly” environment?

References

Baum, P.F. (1922). Judas's red hair, The Journal of English and Germanic Philology, 21, 520-529.

Curry, W.C. (1916). The Middle English Ideal of Personal Beauty, as found in the Metrical Romances, Chronicles, and Legends of the XIII, XIV, and XV Centuries. Baltimore: J.H. Furst Co.

Ellis, H. (2007 [1905]). Studies in the Psychology of Sex, Volume 4 (of 6), Teddington, Echo Library.

Flanagan, N., E. Healey, A. Ray, S. Philips, C. Todd, I.J. Jackson, M.A. Birch-Machin, & J.L. Rees. (2000). Pleiotropic effects of the melanocortin 1 receptor (MC1R) gene on human pigmentation, Human Molecular Genetics, 9, 2531-2537.

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. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103.

Frost, P. (1994). Geographic distribution of human skin colour: A selective compromise between natural selection and sexual selection? Human Evolution, 9, 141-153.

Keeler, C.E. (1947). Coat color, physique, and temperament. Materials for the Synthesis of Hereditary Behavior Trends in the Lower Mammals and Man, The Journal of Heredity, 38, 271-277.

Mogil, J.S., S.G. Wilson, E.J. Chesler, A.L. Rankin, K.V. S. Nemmani, W.R. Lariviere, M.K. Groce, M.R. Wallace, L. Kaplan, R. Staud, T.J. Ness, T.L. Glover, M. Stankova, A. Mayorov, V.J. Hruby, J.E. Grisel, & R.B. Fillingim. (2003). The melanocortin-1 receptor gene mediates female-specific mechanisms of analgesia in mice and humans, PNAS, 100, 4867–4872.

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.

Thelen, T.H. (1983). Minority type human mate preference. Social Biology, 30, 162-180.

Wikipedia. Red hair
http://en.wikipedia.org/wiki/Red_hair

Is eye color sex-linked?

Averaged face of blue-eyed male subjects (left). Averaged face of brown-eyed male subjects (right). Czech population. (Kleisner et al., 2010)

If sexual selection of women diversified the eye color of early Europeans, the new colors should tend to be sex-linked, since the selection targeted women more than men. There is now evidence that blue eyes are linked to feminization of face shape.

Throughout most of the world, humans have brown eyes, black hair, and varying shades of dark skin. An exception is Europe, especially its northern and eastern portions. Here, eyes are not only brown but also blue, gray, hazel, or green. Hair is not only black but also brown, flaxen, golden, or red. Finally, skin has been whitened to the end point of depigmentation.

How can we explain this unusual color pattern? Is it simply due to lightening of skin color? In other words, did reduction of skin pigmentation incidentally reduce eye and hair pigmentation? The diverse palette of eye and hair colors would thus be a side effect of selection for lighter skin.

This explanation is dubious. For one thing, the gene loci are not the same. European skin has whitened mainly through allelic change at SLC45A2 (AIM1) and SLC24A5 (Soejima et al., 2005; Voight et al., 2006). European hair has diversified in color through a proliferation of new alleles at MC1R (Makova & Norton, 2005; Rana et al., 1999). European eyes have diversified in color mainly through a proliferation of new alleles at the OCA2-HERC2 gene complex (Duffy et al., 2007; Kayser et al., 2008; Sturm & Frudakis, 2004; Sturm et al., 2008).

Some of these novel hair and eye colors are also associated with lighter skin, notably the red hair and blue eye phenotypes. But why would selection for lighter skin lead to a proliferation of new alleles for hair and eye color—most of which have little or no influence on skin color? Why is it that red hair and blue eyes have not reached fixation in any human population, even those with milk-white skin?

Sexual selection?

I have argued that the cause was an intensification of sexual selection among early Europeans, specifically sexual selection of women (Frost, 2006; Frost, 2008). When too many women have to compete for too few men, there is selection for visible female traits that hyperstimulate certain algorithms in the male brain, particularly those for gender recognition or fertility assessment.

Among hunter-gatherers—and all humans were hunter-gatherers until 10,000 years ago, sexual selection of women tends to intensify farther away from the equator. On the one hand, hunting distances lengthen, thus increasing male mortality. On the other, polygyny becomes less common because women are less able to provide for themselves and their children in winter, thus making it costlier for a man to provide for a second wife. Result: a growing imbalance between the numbers of women and men on the mate market.

Among early modern humans, these two equator-to-arctic trends reached a common end-point in the steppe-tundra of northern Eurasia, such as existed during the last ice age (25,000 – 10,000 years ago). Hunting distances were very long because almost all food came from highly mobile herds of mammals, notably reindeer. Male provisioning was similarly at a maximum, women having little or no food autonomy.

The Eurasian steppe-tundra was continuously inhabited only in portions of its European end, where it ran farther south because of the large icecap over Scandinavia and where the moderating influence of the Atlantic Ocean and the Gulf Stream made the climate moister and milder. Here, the effects of intense sexual selection could accumulate and be passed on from generation to generation. Conversely, northern Asia appears to have suffered episodes of complete depopulation, particularly at the height of the last ice age.

Sexual selection: color novelty and color diversification

When sexual selection is weak, the adaptive equilibrium is dominated by selection for a dull, cryptic appearance that reduces detection by predators (Kirkpatrick, 1987). As sexual selection grows stronger, the equilibrium shifts toward a more noticeable appearance that retains the attention of potential mates, typically by means of vivid and/or novel colors.

One outcome may be a polymorphism of brightly colored phenotypes, due to selection shifting to scarcer and more novel hues whenever a color variant becomes too common (Endler, 1980; Frost, 2006; Hughes et al., 1999; Hughes et al., 2005; Olendorf et al., 2006). This frequency dependence has been shown in humans. Thelen (1983) presented male participants with slides showing attractive brunettes and blondes and asked them to choose, for each series, the woman they would most like to marry. One series had equal numbers of brunettes and blondes, a second 1 brunette for every 5 blondes, and a third 1 brunette for every 11 blondes. Result: the rarer the brunettes were in a series, the likelier any one of them would be chosen.

But why would this stronger selection diversify hair and eye color while simply whitening skin color? The answer seems to be that sexual selection acts on skin color not only through rare-color preference but also by hyperstimulating a gender-recognition algorithm, i.e., by accentuating a visible female-specific trait. In our species, female skin has less melanin and hemoglobin than does male skin, i.e., women look paler, men browner and ruddier (Edwards & Duntley, 1939; Hulse, 1967; Jablonski & Chaplin, 2000).

Sex linkage?

If European skin had whitened through selection for lighter-skinned women, it should have whitened more in women than in men, thus becoming more sexually dimorphic. Yet skin color actually seems to be less dimorphic in Europeans than in other humans (Madrigal & Kelly, 2006). This finding does not necessarily invalidate the sexual selection hypothesis. It may be that the pigmentary sex difference cannot fully express itself in light-skinned populations. Skin color is dimorphic because girls progressively lighten in color during adolescence, and such lightening may be less easily expressed if melanin production is already low. Indeed, this dimorphism seems to be almost absent in people whose skin starts off with very little pigment, such as Dutch and Belgian subjects (Frost, 2007).

And hair and eye color? Sexual selection of women should favor novel hair and eye colors more so in women than in men. Granted, both polymorphisms arose over a short and relatively recent span of time, so sexual selection would have worked with those alleles that were initially available and, for the most part, not sex-linked. But surely a few of these mutant alleles would have been sex-linked and, as such, favored over non-sex-linked ones.

This does seem to be the case with hair color. Blond hair darkens with age more slowly in women than in men (Olivier, 1960, p. 74). A ‘digit ratio’ study indicates that prenatal exposure to estrogen is higher in individuals with blond hair or non-brown eyes (Mather et al., unpublished). The same study, however, found no evidence of sexual dimorphism. Women and men had roughly the same proportions of hair and eye colors among the 18-to-38 year olds under study. Such a dimorphism, if it does exist, may be a transient one limited to younger age groups.

Moreover, Kleisner et al. (2010) have found an apparent sex linkage between blue eyes and feminization of face shape. They initially wished to determine whether eye color influences perception of male dominance, using facial pictures of Czech men. The results showed that brown-eyed men were rated as more dominant than blue-eyed men. As a control, the authors repeated the experiment after altering the facial photos of the brown-eyed men to make them blue-eyed. These altered photos were still rated as more dominant.

Careful study of the photos revealed that the brown-eyed men had more masculine facial features:

In contrast with blue-eyed males, brown-eyed males have statistically broader and rather massive chins, broader (laterally prolonged) mouths, larger noses, and eyes that are closer together with larger eyebrows. In contrast, blue-eyed males show smaller and sharper chins, mouths that are laterally narrower, noses smaller, and a greater span between the eyes.

The perception of brown-eyed men as more dominant is thus due to their more masculine facial appearance—and not to their brown eyes. The authors suggest that some kind of sex linkage may be responsible, while adding: “Repeating this study in other populations with polymorphism in eye color can test this hypothesis.”

If true, this finding would be consistent with Liberton et al. (2009) who found that European face shape has differentiated from West African face shape through a selective force that has acted primarily on women. Both findings, in turn, would support my argument that many of the differences we see among human populations are not due to differences in natural selection, and hence differing natural environments. Instead, the cause lies in differing intensities of sexual selection, and whether this selection has primarily targeted men or women (Frost, 2008).

When men are the prime targets of sexual selection, as in tropical ‘female farming’ societies, the result is accentuation of certain male features. Meanwhile, there is a slackening of female-targeted sexual selection, which leads to women having a more functional and less ornamental appearance. This pattern is reversed when women are the prime targets of sexual selection (Frost, 2008).

Ethnic substructure?

There is admittedly an alternate explanation for the above finding: ethnic substructure among the Czech subjects. The Czech Republic has historically been home to ethnic minorities who statistically differ from ethnic Czechs in facial appearance, i.e., Jews, Germans, and Roma. Jews and Roma, like other populations of Mediterranean or southwest Asian origin, tend to have brown eyes and a more robust face shape. Conversely, Germans are likelier to have blue eyes and more gracile faces. Although the Jewish and German communities were severely decimated during World War II and its aftermath, with many survivors later emigrating, there still remain significant numbers of Czech citizens who are wholly or partly of Jewish or German origin. Since WWII, there has also been an influx of Roma into the Czech Republic.

It would be difficult to rule out this kind of explanation, even if one questioned the subjects of the study. After the last war, many Czech citizens of Jewish or German origin felt it best to conceal their ancestry, for fear of discrimination or even expulsion from the country. Today, their grandchildren may be completely unaware of their origins.

This is all the more reason to replicate the results with subjects from another population, preferably one with as little ethnic substructure as possible.

References

Duffy, D.L., G.W. Montgomery, W. Chen, Z.Z. Zhao, L. Le, M.R. James, N.K. Hayward, N.G. Martin, & R.A. Sturm. (2007). A three-single-nucleotide polymorphism haplotype in intron 1 of OCA2 explains most human eye-color variation. American Journal of Human Genetics, 80, 241-52.

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

Endler, J.A. (1980). Natural selection on color patterns in Poecilia reticulata. Evolution, 34, 76‑91.

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://www.jsecjournal.com/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.

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103.

Hughes, K.A., L. Du, F.H. Rodd, & D.N. Reznick. (1999). Familiarity leads to female mate preference for novel males in the guppy, Poecilia reticulata. Animal Behaviour, 58, 907-916.

Hughes, K.A., F.H. Rodd, & D.N. Reznick. (2005). Genetic and environmental effects on secondary sex traits in guppies (Poecilia reticulata). Journal of Evolutionary Biology, 18, 35-45.

Hulse, F.S. (1967). Selection for skin color among the Japanese. American Journal of Physical Anthropology, 27, 143-156.

Jablonski, N.G., & G. Chaplin. (2000). The evolution of human skin coloration. Journal of Human Evolution, 39, 57-106.

Kayser, M., F. Liu, A.C.J.W. Janssens, F. Rivadeneira, O. Lao, K. van Duijn, M. Vermeulen, P. Arp, M.M. Jhamai, W.F.J. van Ijcken, J.T. den Dunnen, S. Heath, D. Zelenika, D.D.G. Despriet, C.C.W. Klaver, J.R. Vingerling, P.T.V.M. de Jong, A. Hofman, Y.S. Aulchenko, A.G. Uitterlinden, B.A. Oostra, & C.M. van Duijn. (2008). Three genome-wide association studies and a linkage analysis identify HERC2 as a human iris color gene. The American Journal of Human Genetics doi:10.1016/j.ajhg.2007.10.003

Kirkpatrick, M. (1987). Sexual selection by female choice in polygynous animals. Annual Review of Ecology and Systematics, 18, 43-70.

Kleisner, K., T. Kočnar, A. Rubešova, and J. Flegr. (2010). Eye color predicts but does not directly influence perceived dominance in men, Personality and Individual Differences, 49, 59–64.

Liberton, D.K., K.A. Matthes, R. Pereira, T. Frudakis, D.A. Puts, & M.D. Shriver. (2009). Patterns of correlation between genetic ancestry and facial features suggest selection on females is driving differentiation. Poster #326, The American Society of Human Genetics, 59th annual meeting, October 20-24, 2009. Honolulu, Hawaii.

Mather, F., J.T. Manning, & P.E. Bundred. (unpublished). 2nd to 4th digit ratio, hair and eye colour in Caucasians: Evidence for blond hair as a correlate of high prenatal oestrogen.

Makova, K, & H. Norton. (2005). Worldwide polymorphism at the MC1R locus and normal pigmentation variation in humans. Peptides, 26, 1901-1908.

Olendorf, R., F.H. Rodd, D. Punzalan, A.E. Houde, C. Hurt, D.N. Reznick, & K.A. Hughes. (2006). Frequency-dependent survival in natural guppy populations. Nature, 44, 633-636.

Olivier, G. (1960). Pratique anthropologique. Paris: Vigot Frères.

Rana, B.K., D. Hewett‑Emmett, L. Jin, B.H.-J. Chang, N. Sambuughin, M. Lin, S. Watkins, M. Bamshad, L.B. Jorde, M. Ramsay, T. Jenkins, & W-H. Li. (1999). High polymorphism at the human melanocortin 1 receptor locus. Genetics, 151, 1547‑1557.

Soejima, M., H. Tachida, T. Ishida, A. Sano, & Y. Koda. (2005). Evidence for recent positive selection at the human AIM1 locus in a European population. Molecular Biology and Evolution, 23, 179-188.

Sturm, R.A., D.L. Duffy, Z.Z. Zhao, F.P.N. Leite, M.S. Stark, N.K. Hayward, N.G. Martin, & G.W. Montgomery. (2008). A single SNP in an evolutionary conserved region within intron 86 of the HERC2 gene determines human blue-brown eye color. The American Journal of Human Genetics, 82, 424-431.

Sturm, R.A., & T.N. Frudakis. (2004). Eye colour: portals into pigmentation genes and ancestry. Trends in Genetics, 20, 327-332.

Thelen, T.H. (1983). Minority type human mate preference. Social Biology, 30, 162-180.

Voight, B.F., S. Kudaravalli, X. Wen, & J.K. Pritchard. (2006). A map of recent positive selection in the human genome. PLoS Biology, 4(3), e72 doi:10.1371/journal.pbio.0040072

Blonde jokes aren't funny

The stereotype is not hard to summarize. When a blonde isn’t dumb, she’s lascivious. This is no laughing matter. In fact, a lot of people seem to believe it according to a British survey:

Blondes may have more fun - but it comes at a price. Men don't trust them. A study found that while fair-haired women are considered to be the most adventurous in bed, brunettes are seen as more reliable in a relationship ... and more sexy. In a poll of 1,500 men, more than 60 per cent thought dark-haired girls were the most trustworthy and loyal, compared with just 14 per cent of blondes. The result is men feel brunettes make the best wives.

[…] Commenting on the study for Philips Sensual Massagers, spokesman Karen Moore said: 'Blondes have always had a reputation for being fun, carefree and adventurous and it seems that can also be applied to relationships, as men think they have the best skills when it comes to the bedroom.' (Daily Mail, 2010)

Actually, blondes have not always had this reputation. A very different one emerges from a study of Victorian-era novels:

In each a blonde maiden opposes a brunette, and in each the blonde is preferred. When the ending is happy, the blonde marries the hero; while the brunette is deserted. Most significantly, the blondeness and the darkness are continually emphasized by the authors until their symbolic intention becomes unmistakable. And this symbolic intention is always the same. The maiden with blue eyes and blonde hair is invariably “innocent,” “good,” and “pure”; while the dark lady is “impetuous,” “ardent,” and “passionate.” (Carpenter, 1936, p. 254)

This other study concludes: “In the mid-nineteenth century golden hair became an attribute of the pure and innocent maiden; while dark hair suggested the woman of passion and experience.”

Some hair-color preferences are undoubtedly innate, e.g., rare-color preference (Frost, 2006). Most, however, seem to be culturally constructed. They are specific to a time and place. They are also specific to the social dynamic that links the observer to the observed. If this dynamic is ignored, one might conclude that light-haired women are indeed sexually freer than dark-haired women, all other things being equal. But all other things were not equal when this stereotype took shape. Light hair and dark hair were proxies for ethnicity.

The current blonde stereotype began in the U.S. of the early 20th century. It was a product of ethnic contact between the native-born population and darker-haired immigrants (Italians, Jews, Greeks, etc.) who were often shocked by the relative sexual freedom of ‘American’ women. This attitude existed in different communities, but it entered the mainstream culture primarily via Jewish immigrants and specifically through their contributions to art and literature. It is a common theme in Jewish-American novels:

The exotic female in Jewish life is the sexy shiksa, frequently a blue-eyed blonde who offers gratifications withheld, at least until marriage, by proper Jewish girls. […] A blend of arrogance and defensiveness prompts many Jews to claim that shiksas are more carnal and promiscuous than women of their own faith because Christians are less intelligent, refined, and clean than themselves. Goyishe Kopf (literally translated as gentile head), the Yiddish colloquialism for stupidity, exemplifies the traditional contempt for Christians. (Jaher, 1983)

This theme entered popular American culture through fiction, motion pictures, and comedy routines, with well-known examples including the novel Portnoy’s Complaint by Philip Roth and the typecasting of Marilyn Munroe in vamp roles (Jaher, 1983).

The ‘dumb blonde’ stereotype gradually spread outside the U.S. As a rural Ontario teenager in the 1970s I heard this term on American sitcoms, but it had no connection to my reality. Nor were the blondes at my school thought to be sexually permissive. In the late 1980s, as a doctoral student in Quebec City, I remember the puzzlement that initially greeted blonde jokes, this humor having no relation to existing beliefs about hair color in French Canada. Today, blondes are routinely stereotyped throughout Canada as being sluttish and stupid, as if they have always been so.

This stereotype likewise came late to Europe. In the mid-1960s, Bastide (1967, p. 326) noted the following about the movie industry: “In Europe, a blond is usually the heroine, and a brunette the dangerous woman. In Brazil, the dark woman is loving and faithful, while the blond is the vamp who leads a man to ruin.”

Several generations now separate Americans from the social dynamic that created the current blonde stereotype. This is less true in northwestern Europe, where recent decades have seen immigration from North Africa, the Middle East, and South Asia. For these immigrant communities, light-colored hair symbolizes European ethnicity and, by extension, relative equality of men and women, low importance of female virginity, permissive attitudes to pre-marital sex, etc. Such stereotyping has been reported from Sweden, as noted in the following news article:

"Ah, girl, blond whore!"'

Josephine' was met with these words on the first school day at a high-school in an immigrant-dominated suburb south of Stockholm. Josephine was quite baffled, since aside from her hair color there was nothing about her appearance that would indicate she was promiscuous. She didn't use makeup and had completely neutral clothing. It was exclusively her hair-color that branded her a 'whore'.'

Josephine' is one of the informants for researcher Maria Bäckman, who did an ethnographic field study in a suburb south of Stockholm, where ethnic Swedes make up about 20% of the population.

[…] In her study she focused on ethnic Swedish girls. They experience being linked to the notion of free, Swedish sexuality, which in the densely immigrant suburbs is not necessarily linked with something positive. The strategy for the suburb girls was therefore to play down their Swedish identity.

"Several dyed their hair. Not necessarily because they wanted to look like immigrants, but because they didn't want to look so Swedish," says Bäckman.
(Brandvold, 2010)

Conclusion

Stereotypes are not merely observations of reality. They also reflect the power relationship between the observer and the observed. Too often, the target is a group that cannot fight back. Albinos, for example, have increasingly appeared in films as hit men and other villains even though their poor eyesight makes such roles impossible in real life. From the 1960s to 2006, they appeared as ‘bad guys’ in sixty-eight films (Wikipedia, 2010). They suited the role perfectly, being easy to stigmatize and yet numerically too weak to retaliate.

Blondes have similarly faced media-driven stereotyping, and this stereotyping has persisted for similar reasons. It incurs few social penalties. It’s like the little boy who gets beaten up just because he’s weaker than the bullies who gang up on him.

References

Bastide, R. (1967). Color, racism, and Christianity, Daedalus, 96, 312-327.

Brandvold, A. (2010). Mobbet fordi hun er hvit, Klassekampen, May 8, 2010.

http://www.klassekampen.no/57468/article/item/null/mobbet-fordi-hun-er-hvit (English translation at: http://islamineurope.blogspot.com/2010/05/norwaysweden-when-locals-become.html

Carpenter, F.I. (1936). Puritans preferred blondes, New England Quarterly, 9, 253-272.

Daily Mail. (2010). So blondes really do have more fun: Men claim brunettes make the best wives, but fair haired women are better in bed, Daily Mail, February 13, 2010
http://www.dailymail.co.uk/femail/article-1250520/Blondes-really-fun-Men-claim-brunettes-make-best-wives-fair-haired-women-better-bed.html

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103.

Jaher, F.C. (1983). The quest for the ultimate shiksa, American Quarterly, 35, 518-542.

Swami, V., M. Rozmus-Wrzesinska, M. Voracek, T. Haubner, D. Danel, B. Pawłowski, D. Stanistreet, F. Chaplin, J. Chaudhri, P. Sheth, A. Shostak, E.X. Zhang, A. Furnham. (2008). The influence of skin tone, body weight, and hair colour on perceptions of women’s attractiveness and health: A cross-cultural investigation. Journal of Evolutionary Psychology, 6, 321-341.

Wikipedia (2010). Albinism in popular culture.
http://en.wikipedia.org/wiki/Albinism_in_popular_culture

Blond Inuit?

One of the mysteries of anthropology is the reported presence of ‘blond’ Inuit in the western Canadian Arctic, specifically on and around Victoria Island. They were first noticed by the explorer Sir John Franklin and by Alaskan whalers.

The travellers who have been most surprised by the appearance of the Victoria Island Eskimos are those who are most used to Eskimos of the regular or “pure” type. Such a party were Klinkenberg’s white and (Alaskan) Eskimo crew of the American whaling ship Olga … and it was through her captain and crew that I first half-realized that the people of western Victoria Island were conspicuously different from other Eskimos. … What half-convinced me that he [the captain] was right was the emphatic corroboration of the Alaska Eskimo members of Klinkenberg’s crew, who said that the Victoria Islanders were in appearance like a group of half-castes, although they were wholly Eskimo in language and customs. (Stefansson, 1908, pp. 375-376)

These impressions were confirmed by the anthropologist Vilhjalmur Stefansson for Victoria Island and by the anthropologist Knud Rasmussen for adjacent islands:

In reality these blond types are not peculiar to Victoria Island. In King William Island and on Back River, as well as on Kent Peninsula, I found types which had exactly the same outward characteristics, the same light complexion, the same reddish or brownish hair, the gray and even nearly blue eyes, and remarkably abundant beards—something which is elsewhere uncommon among Eskimos.
(Stefansson, 1908, p. 379)

Stefansson advanced four possible explanations: a) recent European intermixture with whalers or fur traders; b) ancient European intermixture with the Greenland Norse; c) ancient migration of a fair-haired Eurasian people from across the Bering Strait; and d) independent mutation. He was skeptical about the first two explanations:

… no whaler or other person familiar with it has ever suggested that any whaler came in contact with the Victoria Islanders before Captain Klinkenberg in 1905.

The only tenable hypothesis in connection with whaling is that the European blood may have come from the east side of the continent through the Americans, Scotch, and others who have engaged in Hudson Bay and Baffin Bay whaling for centuries. Here we are dealing with no impossibility any more than we were in the case of the earlier and more numerous Greenland Norsemen. But if the mixing of races is so recent, it would appear that it should be most conspicuous farther east where the whalers had their headquarters, fading away as one goes westward. The opposite is the case.
(Stefansson, 1908, pp. 377-378)

Stefansson opted for the last explanation as the most probable: “It is possible that for some so-called accidental reason blond individuals may have been born from time to time in the past from parents of pure Eskimo blood, and that these may have perpetuated themselves” (Stefansson, 1908, p. 381).

Some new light has been shed by a team of researchers headed by Palsson (2008). They collected genetic data from 299 Inuit on Victoria Island and at adjacent locations, as well as from other Inuit or Inuit-related groups (Greenland Inuit, Chukchi, Siberian Yupiit, and Alaskan Aleut). No evidence of European admixture is apparent in the Victoria Island Inuit with respect to either maternally or paternally inherited lineages. But there is evidence of maternal lineages from a pre-Inuit source, possibly the Dorset people who inhabited the Canadian Arctic a thousand years ago.

What conclusion should we draw? Palsson (2008) concluded that the existence of blondism among the Victoria Island Inuit had been blown out of all proportion. Alternately, it may be that new alleles for hair and eye color arose independently through mutation, with some kind of selection pressure favoring these color traits over the original black hair and brown eyes. Finally, it may be that a pre-Inuit population of Eurasian origin, perhaps the Dorset or even the earlier Paleoeskimos, had a significant incidence of fair hair and fair eyes. Such traits might then have persisted through admixture in this Inuit group. The last possibility might not be so far-fetched, since fair hair has been reported among the Yukaghir of eastern Siberia (von Hellwald, 1882).

References

Palsson, G. (2008). Genomic anthropology. Coming in from the cold? Current Anthropology, 49, 545-568.

Stefansson, V. (1927). My Life with the Eskimos. New York: The MacMillan Co.

von Hellwald, F. (1882). Völkerkunde, Nurnberg.