Red is beautiful: Perceived femininity of skin color in an African population

 

Perceived masculinity and femininity of facial skin color. Cameroonian women rated faces of Cameroonian men, and Cameroonian men rated faces of Cameroonian women (Fiala et al. 2022, Supplementary Material).

 

 

 

Women are the fair sex. They are paler than men, who conversely are ruddier and browner. Today, that sexual dimorphism is hardly noticed in Western societies, having been overwhelmed by much larger differences of race and ethnicity and further obscured since the 1920s by the tanning fad (Segrave 2005). But it was noticed earlier. Wherever the visual arts developed—ancient Egypt, the Greco-Roman world, early South and East Asia, Mesoamerica—female figures were given a lighter hue and male figures a darker one (Capart 1905, pp. 26-27; Eaverly 2013; Frost 2010, pp. 35-81; Pallottino 1952, pp. 34, 45, 73, 76-77, 87, 93, 95, 105, 107, 115; Soustelle 1970, p. 130; Tegner 1992; Wagatsuma 1967).

 

Sexual dimorphism in skin pigmentation

 

Skin color was first measured objectively in the 1930s, when spectrophotometers became commercially available. By measuring how much light the skin reflects across the visible spectrum, and how much it absorbs, one could identify its pigments and quantify their relative importance. Edwards and Duntley (1939) concluded that male and female complexions differ because of differing concentrations of melanin (brown), hemoglobin (red), and carotene (yellow).

 

Castration keeps men from acquiring their distinctive complexion:

 

One of the outstanding characteristics of a human male castrate is the paleness of the skin. After treatment with androgenic hormone, however, the individual takes on a darker and more ruddy hue. This observation suggests that the skin of the castrate is deficient in melanin and blood, and that the androgenic hormone increases the content of these substances in the integument. (Edwards et al. 1941)

 

Estrogen has similar but much weaker effects, which are further reduced by the other female hormone, progesterone. Ovariectomy thus has much less impact on female skin than castration has on male skin (Edwards and Duntley 1949). The sex hormones seem to alter skin pigmentation not only through ongoing transient effects but also through permanent organizational effects before birth and at puberty.

 

A hormonal causation is also suggested by the digit ratio. This is the length of the index finger divided by the length of the ring finger, and it tells us the relative proportions of estrogens to androgens in body tissues during development. In adults, the digit ratio correlates with lightness of female skin but not with lightness of male skin (Manning et al. 2004).

 

Sexual dimorphism in tanning capacity

 

Men and women likewise differ in tanning capacity. Men tan more than women even when both are equally exposed to the sun. This was shown in a New Guinea study of three body sites: skin on the unexposed upper inner arm; skin on the exposed forearm; and time spent in the sun. Despite identical sun exposure, the men were darker than the women, and more so on exposed skin (Harvey 1985). The same finding appears in another New Guinea study, whose author ruled out the possibility of the women being less exposed, "as in most parts of New Guinea the adult females are responsible for most of the food cultivation and are therefore exposed almost continuously to sunlight." (Walsh 1964).

 

Differences between human populations

 

Skin color is more sexually dimorphic where people are medium-colored and less so where they are very fair or very dark (Frost 2007; Madrigal and Kelly 2007). This sexual dimorphism cannot fully express itself in a very fair population because female skin encounters a physiological limit when it lightens after puberty. In a very dark population, male skin likewise encounters a physiological limit to further darkening.

 

Are there other population differences? Has this sexual dimorphism evolved differently in different populations?

 

Apparently. A recent paper shows that this sex difference differs qualitatively between Europeans and sub-Saharan Africans. When Fiala et al. (2022) measured the skin color of individuals from the Czech Republic and Cameroon, they found that women had fairer skin in both groups. But their skin was fairer in different ways. Among the Czechs, female skin was less red than male skin, in line with previous studies on European or Euro-American subjects. Among the Cameroonians, however, female skin was redder than male skin, and also more yellow.

 

Adaptation to the natural environment?

 

Is the redder complexion of African women an adaptation to the natural environment? If the skin is better supplied with blood, does it better cope with UV radiation, heat load, skin injuries, or some other aspect of a tropical environment? Let’s examine these three factors, while keeping in mind that they would have to be more fitness-reducing for African women than for African men.

 

UV radiation. The yellow pigment of skin (carotene) does provide some protection from UV (Stahl et al. 2012). So it’s plausible that African women compensate for having less melanin in their skin by having more carotene. On the other hand, there is no evidence that the red pigment of skin (hemoglobin) provides UV protection.

 

Heat load. When more blood is flowing to the skin, heat is radiated away more easily from the body (Hertzman 1959). It may be, then, that the increased redness of African female skin serves to disperse body heat in warmer climates. Nonetheless, we still have to explain why heat load is more fitness-reducing for African women than for African men.

 

Skin injuries. When more blood is flowing to the skin, wounds heals faster because more leukocytes can reach skin tissues and fight potential infections (Mathieu et al. 2006). Again, we still have to explain why this factor would matter more for African women than for African men. Coetzee et al. (2012) raise a similar objection: if ruddiness is attractive because it indicates physical health, why is it considered unattractive in the case of European women or African men?

 

Adaptation to the social environment?

 

Alternatively, the redder complexion of African women may have evolved as an adaptation to the social environment, specifically for gender recognition. In a study using Euro-American participants, people could tell whether a facial photo was male or female, at a rate much higher than chance, even when the image was blurred and provided no useful information other than the degree of redness (Tarr et al. 2001). Sexual dimorphism in skin color has two components: hue (degree of brownness and redness) and luminosity (degree of contrast between lightness of facial skin and darkness of lip/eye area). Hue is the fast channel for gender recognition. If the face is too far away or the lighting too dim, the mind will switch to the slower but more accurate channel of luminosity (Dupuis-Roy et al. 2009; Dupuis-Roy et al. 2019; Jones et al. 2015; Nestor and Tarr 2008a; Nestor and Tarr 2008b; Tarr et al. 2001; Tarr, Rossion, and Doerschner 2002). This gender cue may serve not only to tell men and women apart but also to modify male behavior by reducing aggressiveness and stimulating feelings of care and protection (Frost 2011).

 

African women maintain this gender cue through a different mix of skin pigments. They have more carotene in their skin, and thus a yellower complexion, to offset the loss of UV protection due to having less melanin. Unlike European women, they also have more blood in their skin and thus a redder complexion. Why is this? Perhaps increased redness does not visually alter dark skin in the same way that it visually alters light skin. When redness is increased, the dark skin of African women may look lighter and the light skin of European women may look darker. The social environment has thus favored lighter female skin in both populations, but the mix of pigments is different.

 

This gender cue was studied by Fiala et al. (2022) in their Czech/Cameroonian study. Cameroonian women were asked to rate facial photos of Cameroonian men, and Cameroonian men were asked to rate facial photos of Cameroonian women. The results showed a significant correlation between skin color and perceived masculinity/femininity:

 

The slope between perceived masculinity and colour (higher scores along all three CIELab dimensions, meaning basically lighter skin that allows both redness and yellowness to stand out) of Cameroonian men was negative - 0.29 (CI: - 0.52, - 0.05). In Cameroonian women, the slope between perceived femininity and colour was conclusively positive 0.52 (CI: 0.27, 0.76).

 

[…] More masculine men in the Cameroonian sample have therefore darker, less red, and less yellow skin colour.

[…] More feminine women thus have a lighter, yellower, and redder skin than less feminine women.

 

There was no such correlation among the Czechs. This second finding seems to contradict previous findings that facial skin color is used for gender recognition (see above). In those studies, however, the participants were Euro-American or Euro-Canadian, and they were not necessarily conscious of the visual cues they were using. At least on a conscious level, the sex difference in skin color has lost its social significance within the Western world, largely because of the growing importance of racial/ethnic differences in real life and in the virtual life of advertising and the mass media. In addition, the naturally lighter complexion of women has often been reduced or eliminated through deliberate tanning.

 

Ethnographic data

 

When we were preparing our joint paper on skin color preference, Pierre van den Berghe examined the Human Relations Area Files, a cross-cultural database. He found a strong association in traditional societies between femininity and lightness of skin color: the ideal woman was described as “white” in Europe, the Middle East, and East Asia, as “golden” in Southeast Asia, and as “red” in sub-Saharan Africa (van den Berghe and Frost 1986). We were somewhat surprised to see this idealization of female redness in different ethnographic accounts:

 

Tallensi (Ghana) ‑

“In skin colour they vary from black through chocolate brown to bronze, which the natives call “red” (bon‑ze'e) and regard as the most attractive bodily hue.” (Fortes 1945, p. 7)

 

Hausa (Nigeria) ‑

“Light skin colour, referred to as “red”, ranks high in the Hausa criteria of beauty; many variations of colour, from black to a very light reddish brown are seen.” (Smith 1965, p. 264)

 

Igbo (Nigeria) ‑

“In Ibo culture, however, these yellowish or reddish complexions are considered more beautiful than the darker, ‘blacker,’ complexions.” (Ardener 1954, pp. 71-72)

 

Somali (Somalia) ‑

“Men appreciate women of good height and stature, with good hips and breasts, and plump but not fat.  A reddish tinged skin is thought highly of in preference to a dark dull black.” (Lewis 1962, p. 13)

 

This ideal is explained at some length by Lugira (1970, pp. 34-35) with respect to the Ganda people of Uganda:

 

The Ganda concept of skin pigmentation considers light coloured complexions to be differing shades of white.  A dark brown skin colour is said to be — eruyeru, that is, somewhat white.  A really brown‑reddish‑yellow person is said to be mweru = white, which in comparison would be considered to be blonde; and this in the Ganda aesthetic language is considered as red = myufu, the most perfect skin pigmentation. (Lugira 1970, pp. 34‑35)

 

So the question remains open. Female skin may be redder in Africa because of selection by the natural environment, perhaps as a means to reduce heat load or facilitate wound healing. There is also evidence, however, for selection by the social environment.

 

References

 

Ardener, E.W. (1954). Some Ibo attitudes to skin pigmentation. Man 54: 71-73. http://www.jstor.org/stable/2793760

 

Capart, J. (1905). Primitive Art in Egypt. London: H. Grevel.

 

Coetzee, V., S.J. Faerber, J.M. Greeff, C.E. Lefevre, D.E. Re, and D.I. Perrett. (2012). African Perceptions of Female Attractiveness. PLoS ONE 7(10): e48116. https://doi.org/10.1371/journal.pone.0048116

 

Dupuis-Roy, N., S. Faghel-Soubeyrand, and F. Gosselin. (2019). Time course of the use of chromatic and achromatic facial information for sex categorization. Vision Research 157: 36-43. https://doi.org/10.1016/j.visres.2018.08.004

 

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. https://doi.org/10.1167/9.2.10

 

Eaverly, M.A. (2013). Tan Men/Pale Women. Color and Gender in Archaic Greece and Egypt, a Comparative Approach. Ann Arbor: The University of Michigan Press. https://doi.org/10.3998/mpub.3080238

 

Edwards, E.A., and S.Q. Duntley. (1939).The pigments and color of living human skin. American Journal of Anatomy 65(1): 1-33. https://doi.org/10.1002/aja.1000650102

 

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 & Gynecology 57(3): 501-509. https://doi.org/10.1016/0002-9378(49)90235-5

 

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(1): 119-128. https://doi.org/10.1210/endo-28-1-119

 

Fiala, V., P. Ture?ek, R.M. Akoko, Š. Pokorný, and K. Kleisner. (2022). Africans and Europeans differ in their facial perception of dominance and sex-typicality: a multidimensional Bayesian approach. Scientific Reports 12(1): 6821. https://doi.org/10.1038/s41598-022-10646-6. 

 

Fortes, M. (1945). The Dynamics of Clanship among the Tallensi. London: Oxford University Press.

 

Frost, P. (2007). Comment on Human skin-color sexual dimorphism: A test of the sexual selection hypothesis. American Journal of Physical Anthropology 133(1): 779-781. https://doi.org/10.1002/ajpa.20555

 

Frost, P. (2010). Femmes claires, hommes foncés. Les racines oubliées du colorisme. Quebec City: Les Presses de l'Université Laval, 202 p. https://doi.org/10.7202/006424ar

 

Frost, P. (2011). Hue and luminosity of human skin: a visual cue for gender recognition and other mental tasks. Human Ethology Bulletin 26(2): 25-34. https://www.researchgate.net/publication/256296588_Hue_and_luminosity_of_human_skin_a_visual_cue_for_gender_recognition_and_other_mental_tasks

 

Harvey, R. G. (1985). Ecological factors in skin color variation among Papua New Guineans, American Journal of Physical Anthropology 66(4): 407-416. https://doi.org/10.1002/ajpa.1330660409

 

Hertzman, A.B. (1959). Vasomotor regulation of cutaneous circulation. Physiological Reviews 39(2):280-306. doi: 10.1152/physrev.1959.39.2.280. PMID: 13645236.

 

Jones, A.L., R. Russell, and R. Ward. (2015). Cosmetics alter biologically-based factors of beauty: evidence from facial contrast. Evolutionary Psychology 13(1): https://doi.org/10.1177%2F147470491501300113

 

Lewis, I.M. (1962). Marriage and the Family in Northern Somaliland. Kampala: East African Institute of Social Research.

 

Lugira, A.M. (1970). Ganda Art. Kampala: Osasa pub.

 

Madrigal, L., and W. Kelly. (2006). Human skin-color sexual dimorphism: A test of the sexual selection hypothesis. American Journal of Physical Anthropology 132(3): 470-482. https://doi.org/10.1002/ajpa.20453

 

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(1): 38-50. https://doi.org/10.1016/s1090-5138(03)00082-5

 

Mathieu, D., J.C. Linke, and F. Wattel. (2006). Non-Healing Wounds. Handbook on Hyperbaric Medicine. Springer, pp. 401-428. https://doi.org/10.1007/1-4020-4448-8

 

Nestor, A., and M.J. Tarr. (2008a).The segmental structure of faces and its use in gender recognition. Journal of Vision, 8(7): 7, 1-12. https://doi.org/10.1167/8.7.7 .

 

Nestor, A., and M.J. Tarr. (2008b). Gender recognition of human faces using color. Psychological Science 19(12): 1242-1246. https://doi.org/10.1111/j.1467-9280.2008.02232.x

 

Pallottino, M. (1952). Etruscan Painting. Lausanne: Skira.

 

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

 

Smith, M.F. (1965). Baba of Karo: A Woman of the Muslim Hausa. London: Faber & Faber.

 

Soustelle, J. (1970). The Daily Life of the Aztecs. Stanford, California: Stanford University Press.

 

Stahl, W., and H. Sies. (2012). β-Carotene and other carotenoids in protection from sunlight. The American Journal of Clinical Nutrition 96(5): 1179S–1184S https://doi.org/10.3945/ajcn.112.034819

 

Tarr, M.J., D. Kersten, Y. Cheng, and B. Rossion. (2001). It's Pat! Sexing faces using only red and green. Journal of Vision 1(3): 337, 337a. https://doi.org/10.1167/1.3.337

 

Tarr, M. J., B. Rossion, and K. Doerschner. (2002). Men are from Mars, women are from Venus: Behavioral and neural correlates of face sexing using color. Journal of Vision 2(7): 598, 598a, https://doi.org/10.1167/2.7.598

 

Tegner, E. (1992). Sex differences in skin pigmentation illustrated in art. The American Journal of Dermatopathology 14(3): 283-287.  https://doi.org/10.1097/00000372-199206000-00016

 

van den Berghe, P.L., and P. Frost. (1986). Skin color preference, sexual dimorphism and sexual selection: A case of gene-culture co-evolution? Ethnic and Racial Studies 9(1): 87-113. https://doi.org/10.1080/01419870.1986.9993516

 

Wagatsuma, H. (1967). The social perception of skin color in Japan. Daedalus 96(2): 407-443. http://www.jstor.org/stable/20027045

 

Walsh, R. J. (1964). Variation in the melanin content of the skin of New Guinea natives at different ages. Journal of Investigative Dermatology 42(3): 261-265. https://doi.org/10.1038/jid.1964.59

 

Puberty and skin color

Skin color differentiates between boys and girls after puberty. Before puberty, girls are actually darker-skinned than boys (Kalla 1973; Mesa 1983)

Complexions differ between the sexes: women are paler and men ruddier and browner. Today, this sex difference seems hardly noticeable in Western societies, having been overwhelmed by much larger differences of race and ethnicity and further obscured since the 1920s by the tanning fad (Segrave 2005). Nonetheless, it was noticed in earlier times. A lighter hue was traditionally given to female figures and a darker hue to male figures in the visual arts of all early civilizations, including those of Italy, Greece, Egypt, China, Japan, and Mesoamerica (Capart 1905, pp. 26-27; Eaverly 1999; Pallottino 1952, pp. 34, 45, 73, 76-77, 87, 93, 95, 105, 107, 115; Siepe 2004; Soustelle 1970, p. 130; Tegner 1992; Wagatsuma 1967). This sex difference also appears in ancient Greek poetry, where women are described as “white” and men as “black” (Irwin 1974, pp. 121, 129-155). “White” skin is still key to female identity in many non-Western societies, as shown by interviews with Japanese men: "Whiteness is a symbol of women, distinguishing them from men." "One's mother-image is white" (Wagatsuma 1967, pp. 417-418).

Spectrophotometric studies

With the advent of the spectrophotometer, researchers could study skin color by measuring the percentage of light reflected by the skin, most often at the upper inner arm—where tanning is minimal. An American team thus attributed the differing complexions of men and women to differing concentrations of the three main skin pigments: melanin, hemoglobin, and carotene (Edwards and Duntley 1939). The same team showed that this sex difference was reduced by ovariectomy and even more so by castration (Edwards and Duntley 1949; Edwards et al. 1941). Later research identified puberty as the time when boys and girls diverge in skin color (van den Berghe and Frost 1986). The best controlled studies are those by Kalla (1973) and Kalla and Tiwari (1970) on South Asians and Tibetans and by Mesa (1983) on Spanish participants. The samples are large enough to measure this sexual differentiation by year and by sex. In addition to showing that girls become progressively lighter-skinned than boys during adolescence, these studies also show that girls are actually darker-skinned than boys just before puberty.

These sex and age differences thus seem to be innately programmed, specifically via the sex hormones. This hypothesis is further supported by a study of skin color in monozygotic and dizygotic twins from three age groups: 12 year olds; 13 to 15 year olds; and 16 to 18 year olds. Variance within the twin pairs differed significantly on average between monozygotic and dizygotic twins, thus “indicating a strong genetic component in the variability of skin lightness.” As in other studies, puberty had a stronger effect on female skin color than on male skin color, with girls becoming progressively lighter-skinned. For both sexes, mean within-pair variance did not differ significantly from one age group to the next, further indicating that these age changes are under genetic control (Omoto 1965).

Nonetheless, most people, including academics, have continued to ascribe the differing complexions of men and women to differences in lifestyle (see for example Eaverly 1999 and Irwin 1974). Perhaps girls become lighter-skinned after puberty because they are less free to go outside unaccompanied, as used to be the case in many cultures. The sex difference in skin color should therefore disappear as women come to resemble men in terms of lifestyle. This alternative hypothesis is supported by a recent study of young adults from Ireland, Poland, Italy, and Portugal, which found women to be darker-skinned than men on the upper inner arm, the body site most often used to measure the color of untanned skin (Candille et al. 2012). This finding contradicts findings from earlier studies on Europeans or European-descended participants (van den Berghe and Frost 1986).

Digit ratio studies (2D:4D)

Recently, the innate causation hypothesis has received support from two "digit ratio" studies. This ratio is index finger length divided by ring finger length, and it corresponds to the ratio of androgens to estrogens in the fluids of the developing fetus. A higher ratio indicates more feminization, and a lower ratio more masculinization.

A British team led by John Manning (2004) examined adults of both sexes. Lightness of skin color was found to correlate in women but not in men with digit ratio, i.e., women are lighter-skinned if their body tissues have been exposed to higher estrogen levels. This finding was true for both the left hand and the right hand, although the correlation was stronger for the left hand.

A Polish team led by Aneta Sitek (2018) looked at children just before puberty, when girls are actually darker-skinned than boys. Darkness of skin color was found to correlate in girls but not in boys with digit ratio, i.e., pre-pubertal girls are darker-skinned if their body tissues have been exposed to higher estrogen levels. This finding was true only for the right hand.

For reasons still unclear, the digit ratio of the right hand is more responsive to the sex hormones than the digit ratio of the left hand, as shown by a greater sex difference in digit ratio for the right hand than for the left (Honekopp and Watson 2010). In reviewing the literature, Honekopp and Watson (2010) argue that right-hand digit ratio is a better indicator of prenatal exposure to the sex hormones. Left-hand digit ratio seems to be more affected by hormonal exposure later in life. This is suggested by the findings of a longitudinal study: digit ratio increases in children with age, and this effect is greater for the left hand than for the right hand (Trivers et al. 2006).

Discussion

Digit ratio studies point to a hormonal cause, and not to differences in lifestyle, as the reason why skin color differentiates between boys and girls at puberty. This is consistent with earlier spectrophotometric studies on normal, castrated, and ovariectomized individuals (Edwards and Duntley 1939; Edwards and Duntley 1949; Edwards et al. 1941). Furthermore, most spectrophotometric studies have shown that women are lighter-skinned than men even at the upper inner arm—a body site normally unaffected by tanning (van den Berghe and Frost 1986).

But why were women darker-skinned than men at this body site in a recent study of young adults from Ireland, Poland, Italy, and Portugal? (Candille et al. 2012). One can only conclude that the upper inner arm is no longer a reliable site for measuring the color of untanned skin. Perhaps young Western women now make a point of tanning their underarms because they increasingly shave this part of their body and expose it to view.

References

Candille, S.I., D.M. Absher, S. Beleza, M. Bauchet, B. McEvoy, N.A. Garrison, et al. (2012). Genome-wide association studies of quantitatively measured skin, hair, and eye pigmentation in four European populations. PLoS One 7(10): e48294.

https://doi.org/10.1371/journal.pone.0048294

Capart, J. (1905). Primitive Art in Egypt. London: H. Grevel.

Eaverly, M.A. (1999). Color and gender in ancient painting: A pan-Mediterranean approach. In N.L. Wicker and B. Arnold (Eds). From the Ground Up: Beyond Gender Theory in Archaeology. Proceedings of the Fifth Gender and Archaeology Conference, University of Wisconsin-Milwaukee, (pp. 5-10). Oxford (England): British Archaeological Reports.

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

https://doi.org/10.1002/aja.1000650102 

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 & Gynecology 57(3): 501-509.

https://doi.org/10.1016/0002-9378(49)90235-5 

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(1): 119-128. https://doi.org/10.1210/endo-28-1-119

Honekopp J, S. Watson, (2010). Meta-analysis of digit ratio 2D:4D shows greater sex difference in the right hand. American Journal of Human Biology 22(5): 619-30. https://doi.org/10.1002/ajhb.21054

Irwin, E. (1974). Colour Terms in Greek Poetry. Toronto: Hakkert.

Kalla, A.K. (1973). Ageing and sex differences in human skin pigmentation. Zeitschrift für Morphologie und Anthropologie 65(1): 29-33.

http://www.jstor.org/stable/25756080 

Kalla, A. K. and S.C. Tiwari. (1970). Sex differences in skin colour in man. Acta Geneticae Medicae et Gemellologiae 19(3): 472-476.

https://doi.org/10.1017/S1120962300014876

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 série 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(4): 115-122.

Pallottino, M. (1952). Etruscan Painting. Lausanne: Skira.

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

Siepe, F. (2004). Farben des Eros. Marginalien zur Kulturgeschichte der Liebes- und Schönheitswahrnehmung in Antike und christlichem Abendland. Marburg: Kline.

Sitek, A., S. Koziel, A. Kasielska-Trojan, and B. Antoszewski. (2018). Do skin and hair pigmentation in prepubertal and early pubertal stages correlate with 2D:4D? American Journal of Human Biology, early view 

https://doi.org/10.1002/ajhb.23183

Soustelle, J. (1970). The Daily Life of the Aztecs. Stanford, California: Stanford University Press.

Tegner, E. (1992). Sex differences in skin pigmentation illustrated in art. The American Journal of Dermatopathology 14(3): 283-87. 

https://doi.org/10.1097/00000372-199206000-00016 

Trivers, R., J. Manning, and A. Jacobson. (2006). A longitudinal study of digit ratio (2D:4D) and other finger ratios in Jamaican children. Hormones and Behavior 49(2): 150-156. https://doi.org/10.1016/j.yhbeh.2005.05.023

van den Berghe, P.L., and P. Frost. (1986). Skin color preference, sexual dimorphism and sexual selection: A case of gene-culture co-evolution? Ethnic and Racial Studies 9(1): 87-113. https://doi.org/10.1080/01419870.1986.9993516  

Wagatsuma, H. (1967). The social perception of skin color in Japan. Daedalus 96(2): 407-443.

http://www.jstor.org/stable/20027045  

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.

 

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