Saturday, December 13, 2014

A darker shade of pale

Subjects identified the left-hand image as a woman and the right-hand one as a man. Yet the two images differ only in skin tone. Study by Richard Russell, Sinha Laboratory for Vision Research, MIT.


Skin color differs by sex: women are fairer and men browner and ruddier. Women also exhibit a greater contrast in luminosity between their facial skin and their lip and eye areas. These differences arise from differing concentrations of three skin pigments: melanin (brown); hemoglobin (red); and carotene (yellow). The cause is ultimately hormonal, as shown by studies on castrated and ovariectomized adults, on boys and girls during puberty, and on digit ratios (Edwards and Duntley, 1939; Edwards and Duntley, 1949; Edwards et al., 1941; Frost, 2010; Kalla and Tiwari, 1970; Manning et al., 2004; Mesa, 1983; Omoto,1965; Porcheron et al., 2013). Women are fairer than men in all human populations. The difference is greatest in people of medium color and least in very dark- or very fair-skinned people, apparently because of "floor" or "ceiling" effects (Frost, 2007). 

This sex difference is used by the human mind for sex recognition. In fact, it's more important for this purpose than other visual cues, like face shape. When subjects are shown an image of a human face, they can tell whether it is male or female even if blurred and differing only in hue and luminosity. Hue provides a "fast channel" for sex recognition. If the facial image is too far away or the lighting too dim, the mind switches to the "slow channel" and relies on luminosity (Bruce and Langton, 1994; Dupuis-Roy et al., 2009; Frost, 2011; Hill et al., 1995; Russell and Sinha, 2007; Russell et al., 2006; Tarr et al., 2001; Tarr et al., 2002).

Age differences

Skin color also differs by age. It can be used to distinguish younger from older women, since the contrast in luminosity between facial skin and the lip/eye areas decreases with age (Porcheron et al., 2013). It can also be used to recognize infants. All humans are born with very little melanin, and the resulting pinkish-white skin is often remarked upon in different cultures.

This is especially so where adults are normally dark-skinned, in striking contrast to newborns. In Kenya, the latter are often called mzungu ('European' in Swahili), and a new mother may ask her neighbors to come and see her mzungu (Walentowitz, 2008). Among the Tuareg, children are said to be whitened by the freshness and moisture of the womb (Walentowitz, 2008). The situation in other African peoples is summarized by a French anthropologist: "There is a rather widespread concept in Black Africa, according to which human beings, before 'coming' into this world, dwell in heaven, where they are white. For, heaven itself is white and all the beings dwelling there are also white. Therefore the whiter a child is at birth, the more splendid it is" (Zahan, 1974, p. 385). A Belgian anthropologist makes the same point: "black is thus the color of maturity [...] White on the other hand is a sign of the before-life and the after-life: the African newborn is light-skinned and the color of mourning is white kaolin" (Maertens, 1978, p. 41). 

This infant/adult difference is evolutionarily old, being present in nonhuman primates. In langurs, baboons, and macaques, the newborn's skin is pink while the adult's is black. This visual cue not only helps adults to locate a wayward infant but also seems to induce a desire to defend and provide care (Jay, 1962). Humans may respond similarly to the lighter color of infants and women. This would be consistent with a tendency by the adult female body to mimic the newborn body in other ways: face shape; pitch of voice; amount of body hair; texture and pliability of the skin; etc. Over time, women may have come to resemble this 'infant schema' because it is the one that can best reduce aggressiveness in a male partner and induce him to assume a provider role.

The sun-tanning fad: An aesthetic revolution

The sex-specific aspects of skin color have influenced the development of cosmetics in many cultures. Even in ancient times, women would use makeup to increase the natural contrast in luminosity between their facial skin and their lip/eye areas (Russell, 2009; Russell, 2010). They would also make their naturally fair complexion even fairer by avoiding the sun and applying white powders or bleaching agents.

This feminine aesthetic changed radically in the 1920s with the sudden popularity of sun-tanning throughout the Western world, initially as a health fad. Tanned skin then entered women's fashion and became part of the flapper image, along with bobbed hair, broad shoulders, a relatively flat chest, narrow hips, and long legs. This fashion image was intended to be hermaphroditic, the aim being to energize the erotic appeal of the female body by masculinizing some of its key features (Bard, 1998; Segrave, 2005). 

Has the tanning fad un-gendered skin color? Not wholly, to judge by the above studies on sex recognition. There still seems to be a tendency to prefer a lighter skin tone for women than for men. This was the conclusion of a recent study on how people perceive two skin pigments: melanin (brown) and carotene (yellow). When shown facial images with varying concentrations of melanin and carotene, the subjects had a greater preference for carotene than for melanin. This preference was stronger for female faces than for male faces, irrespective of the observer's sex. Nonetheless, for both male and female faces, the preferred skin color was much darker than it would have been a century ago (Lefevre and Perrett, 2014).

Again, this aesthetic norm has darkened only in the Western world. The tanned look had some popularity among Japanese women in the postwar era up to the 1970s, but it has since gone out of fashion (Ashikari, 2005). It never did catch on elsewhere in Asia (Li et al., 2008). In North America and Europe, the tanned look seems much more persistent, and this persistence suggests that it is locked into place by something else in our cultural environment.

Such as ...? One factor may be the conscious effort to promote images of dark-skinned people in advertising and, more generally, in popular culture. Another factor may be a half-conscious desire in popular culture for more aggressive, "harder" forms of eroticism. This is something that fair skin is less effective at delivering, having been originally part of the infant schema and thus less conducive to that kind of emotional response.



Ashikari, M. (2005). Cultivating Japanese whiteness. The 'whitening' cosmetics boom and the Japanese identity, Journal of Material Culture, 10, 73-91. 

Bard, C. (1998). Les Garçonnes. Modes et fantasmes des Années folles, Flammarion, Paris. 

Bruce, V., and S. Langton. (1994). The use of pigmentation and shading information in recognising the sex and identities of faces, Perception, 23(7), 803-822.

Dupuis-Roy, N., I. Fortin, D. Fiset, and F. Gosselin. (2009). Uncovering gender discrimination cues in a realistic setting, Journal of Vision, 9(2), 10, 1-8.

Edwards, E.A. and S.Q. Duntley. (1949). Cutaneous vascular changes in women in reference to the menstrual cycle and ovariectomy, American Journal of Obstetrics and Gynecology, 57, 501-509.

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

Edwards, E.A., J.B. Hamilton, S.Q. Duntley, and G. Hubert. (1941). Cutaneous vascular and pigmentary changes in castrate and eunuchoid men, Endocrinology, 28, 119-128. 

Frost, P. (2011). Hue and luminosity of human skin: a visual cue for gender recognition and other mental tasks, Human Ethology Bulletin,

Frost, P. (2010). Femmes claires, hommes foncés. Les racines oubliées du colorisme, Québec: Les Presses de l'Université Laval, 202 p.

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.

Hill, H., Bruce, V., and S. Akamatsu. (1995). Perceiving the sex and race of faces: The role of shape and colour, Proceedings of the Royal Society B: Biological Sciences, 261, 367-373. 

Jay, P.C. (1962). Aspects of maternal behavior among langurs, Annals of the New York Academy of Sciences, 102, 468-476.

Kalla, A.K. and S.C. Tiwari. (1970). Sex differences in skin colour in man, Acta Geneticae Medicae et Gemellologiae, 19, 472-476. 

Lefevre, C.E. and D.I. Perrrett. (2014). Fruit over sunbed: Carotenoid skin colouration is found more attractive than melanin colouration, The Quarterly Journal of Experimental Psychology,

Li, E.P.H., H.J. Min, R.W. Belk, J. Kimura, and S. Bahl. (2008). Skin lightening and beauty in four Asian cultures, Advances in Consumer Research, 35, 444-449.

Maertens, J-T. (1978). Le dessein sur la peau. Essai d'anthropologie des inscriptions tégumentaires, Ritologiques I, Paris: Aubier Montaigne. 

Manning, J.T., P.E. Bundred, and F.M. Mather. (2004). Second to fourth digit ratio, sexual selection, and skin colour, Evolution and Human Behavior, 25, 38-50. 

Mesa, M.S. (1983). Analyse de la variabilité de la pigmentation de la peau durant la croissance, Bulletin et mémoires de la Société d'Anthropologie de Paris, t. 10 series 13, 49-60. 

Omoto, K. (1965). Measurements of skin reflectance in a Japanese twin sample, Journal of the Anthropological Society of Nippon (Jinruigaku Zassi), 73, 115-122. 

Porcheron, A., E. Mauger, and R. Russell (2013). Aspects of facial contrast decrease with age and are cues for age perception, PLoS ONE 8(3): e57985 

Russell, R. (2010). Why cosmetics work. In R. Adams, N. Ambady, K. Nakayama, and S. Shimojo. (eds.) The Science of Social Vision, New York: Oxford. 

Russell, R. (2009). A sex difference in facial contrast and its exaggeration by cosmetics, Perception, 38, 1211-1219

Russell, R. (2003). Sex, beauty, and the relative luminance of facial features, Perception, 32, 1093-1107.

Russell, R. and P. Sinha. (2007). Real-world face recognition: The importance of surface reflectance properties, Perception, 36, 1368-1374.

Russell, R., P. Sinha, I. Biederman, and M. Nederhouser. (2006). Is pigmentation important for face recognition? Evidence from contrast negation, Perception, 35, 749-759.

Segrave, K. (2005). Suntanning in 20th Century America, Jefferson (North Carolina), McFarland & Co. 

Tarr, M. J., Kersten, D., Cheng, Y., and Rossion, B. (2001). It's Pat! Sexing faces using only red and green, Journal of Vision, 1(3), 337, 337a

Walentowitz, S. (2008). Des êtres à peaufiner. Variations de la coloration et de la pigmentation du nouveau-né, in J-P. Albert, B. Andrieu, P. Blanchard, G. Boëtsch, and D. Chevé (eds.), Coloris Corpus, (pp. 113-120), Paris: CNRS Éditions, 2008.

Zahan, D. (1974). White, Red and Black: Colour Symbolism in Black Africa, in A. Portmann and R. Ritsema (eds.) The Realms of Colour, Eranos 41 (1972), 365-395, Leiden: Eranos.


Anonymous said...

Tanning for women may be questionable and recent, but men in white societies have historically been expected to be tan if they were upper class. It was a sign that you spent time outdoors hunting, in athletics, or in military enterprise. Greeks saw a man with untanned skin as one who spent all his time indoors with women, i.e., effeminate, or a slave who had to spend all day in labor (often indoors). This is explicit in many passages, including in Plato's Republic. Ancient Egyptians had a similar convention in how they represented the Pharaoh, nobles, etc., vs. the women. Similarly in recent times having tan skin for a man meant you are someone who spends his time as a sportsman, yachting, etc., that you were upper class.

There is an opposite claim made by the middle and lower middle classes who don't know about this very long historical trend. Insecure about their social position, and wary lest they should be confused with the lower classes that labored in agriculture, the merchant middle and lower middle class in the Near East, southeast Asia, and parts of Europe as well, assiduously avoided (and avoid) tanning. But from an aristocratic point of view the males of these classes are unmanly.

America's racial politics has made tanning begin to go out of favor among whites for reasons hinted at in this post.

Anonymous said...

In Brazil tanning is very popular except for those who are racially borderline and who would become too dark in the sun or who have facial features that, combined with a tan, would show them to be nonwhite. But the upper class goes to the beach and tans and having an untanned body is taken to mean, again, that you are the sort of person to spend all day indoors.

I have seen Scandinavians in Rio whose skin turns more brown than some of the locals'. No one can confuse them for nonwhites though. It is interesting the extent to which skin color is not reliable for predicting race though; these Scandis were a very deep golden brown. Japanese turn an almost purplish black when they tan.

Santoculto said...

Scandinavians look more as slavic people, blonde and relativelly good to be tanned.

Seems, ''atlantic euro genes'', northern Portugal, passing by all Britain island until Estonia, tend to have more sensible, pale and or reddish skin than slavic and nordic blondes, probably because in these areas we have more people with recessive ''red haired genes'' or less ''asiatic genes'' reduce skin paleness.

AWC said...

My thoughts on sun tanning among women:


W.LindsayWheeler said...

I want to thank Peter Frost for his posts and his research. It is quite enlightening and interesting. Thank you for your time and effort. I also thank the commenters for their input as well.

The world is a marvelous place. My only wish is that humans would respect the Natural Order of things. It is called respect. Respect for what God as done--and it is ALL Good.

Anonymous said...

@LindsayWheeler - "It is quite enlightening"

I see what you did there.

Stephen said...

In the example image the bleaching version on the left removes allot of making the nose eye sockets and other features look shallower. So you may not be demonstrating the effects of pigmentation on real faces so much as the effects of removing shading information from 2d images. To remove this confounding factor you may have to do 3d renderings of differently pigmented faces preferably give a stereoscopic presentation. rather that manipulating the contrast on averaged photos.

Anonymous said...

"these Scandis were a very deep golden brown"

I get like that. I wonder if it's connected to Amerindian coloring somehow?