Unintended consequences

Oral contraceptives suppress not only ovulation but also concurrent behavioral and attitudinal changes, including the desire to look more attractive. Has "the pill" changed our culture?

The oral contraceptive pill prevents pregnancy by suppressing ovulation—in short, by fooling a woman's body into thinking it is already pregnant. In addition to medical side effects, "the pill" also seems to modify behavior and attitude, often subtly. Whereas women are more likely to initiate sexual behavior at ovulation, this effect is suppressed in women on the pill (Adams et al. 1978). The latter also prefer men whose faces are less masculine (Little et al. 2002) and lighter-skinned (Frost 1994).

Among non-pill-users, ovulation coincides with greater use of cosmetics and increased time spent putting on cosmetics (Guéguen 2012). This behavioral effect seems to be likewise suppressed by pill use:

We photographed a sample of women (N = 36) who self-reported whether or not they use the contraceptive pill, as well as their cosmetic habits. A separate sample of participants (N = 143) rated how much makeup these target women appeared to be wearing. We found that women not using the contraceptive pill (i.e., naturally cycling women) reported spending more time applying cosmetics for an outing than did women who use the contraceptive pill. We also found that the faces of these naturally cycling women were rated as wearing more cosmetics than the faces of the women using the contraceptive pill. (Batres et al. 2018)

These findings are consistent with the results of a study on professional lap dancers. The participants made $335 in tips per 5 hour shift during ovulation, but only $260 per shift during the luteal phase and $185 per shift during menstruation. Lap dancers on contraceptive pills showed no change in earnings over the menstrual cycle (Miller et al. 2007). It's unclear what sort of visual or behavioral cues were suppressed by pill use:

[...] our study did not identify the precise proximal mechanisms that influence tip earnings. These might include the previously documented shifts in body scent, facial attractiveness, soft-tissue body symmetry, waist-to-hip ratio, and verbal creativity and fluency—or they might include shifts in other phenotypic cues that have not yet been studied. We can, however, exclude some possible mediators based on previous exotic dancer research. Tip earnings are unlikely to be influenced by cycle shifts in stage-dance moves, clothing, or initial conversational content because these cues just do not vary much for professional dancers (Miller et al. 2007)

Do women naturally have a more attractive physical appearance at ovulation?

Discussion

The past half-century has seen a trend toward androgyny among women. This trend is usually attributed to feminism and pop culture, but perhaps the latter have in turn been influenced by something else.

Today, "the pill" is used by approximately 100 million women worldwide, particularly in developed countries. Has this widespread use played a role in changing our cultural and ideological environment? 

I'm not suggesting that women look less feminine today simply because more of them are on the pill and thus are hormonally altered. Rather, if a larger proportion of women are in that kind of hormonal state, it will be easier for anti-feminine fashions and ideologies to achieve a critical mass and take off among all women, including those not on the pill.

References

Adams, D.B., A.R. Gold, and A.D. Burt. (1978). Rise in female-initiated sexual activity at ovulation and its suppression by oral contraceptives. New England Journal of Medicine 299: 1145-1150.

https://doi.org/10.1056/NEJM197811232992101  

Batres, C., A. Porcheron, G. Kaminski, S. Courrèges, F. Morizot, and R. Russell. (2018). Evidence that the hormonal contraceptive pill is associated with cosmetic habits? Frontiers in Psychology 9: 1459

https://doi.org/10.3389/fpsyg.2018.01459

Frost, P. (1994b). Preference for darker faces in photographs at different phases of the menstrual cycle: Preliminary assessment of evidence for a hormonal relationship. Perceptual and Motor Skills 79(1): 507-14.

https://doi.org/10.2466/pms.1994.79.1.507.

Guéguen, N. (2012). Makeup and menstrual cycle: near ovulation, women use more cosmetics. The Psychological Record 62: 541-548. 

https://doi.org/10.1007/BF03395819

Little, A.C., B.C. Jones, I.S. Penton-Voak, D.M. Burt, and D.I. Perrett. (2002). Partnership status and the temporal context of relationships influence human female preferences for sexual dimorphism in male face shape. Proceedings of the Royal Society B. 269: 1095-1100. 

https://doi.org/10.1098/rspb.2002.1984

Miller, G., J.M. Tybur, and B.D. Jordan. (2007). Ovulatory cycle effects on tip earnings by lap dancers: economic evidence for human estrus? Evolution and Human Behavior 28: 375-381. https://doi.org/10.1016/j.evolhumbehav.2007.06.002

Facial contrast and femininity

 

How to hyperstimulate a sex-recognition algorithm. Women have higher luminous contrast between their facial skin and their lip/eye color. This contrast effect is influenced not only by degree of lightness but also by degree of redness (source).

Women are fairer in complexion because their skin has less melanin and less blood (Edwards and Duntley, 1939). Male castrates similarly look pale (Edwards et al., 1941). For this reason, relative lightness or darkness of skin seems to be key to sex recognition. People especially focus on the luminous contrast between facial skin and the color of the lips and eyes (Russell, 2009; Russell, 2010; see also Dupuis-Roy et al., 2009):

The luminance contrast between the eyes and the surrounding skin and the lips and the surrounding skin has been termed ‘facial contrast’. Female faces have greater facial contrast than male faces, and facial contrast plays an important role in sex classification and the perception of masculinity and femininity and also attractiveness (Porcheron et al., 2013)

This contrast effect has influenced the development of cosmetics. Different societies, sometimes independently of each other, have invented ways to increase facial contrast by darkening the lips and eye area and, conversely, by lightening facial skin (Russell, 2009; Russell, 2010).

Ancient Egypt was an early center for the development of cosmetics (Dayagi-Mendels, 1989). Indeed, the Egyptians “had most of the cosmetic aids which have ever been devised” (Corson, 1972, p.8), including rouge for the lips and cheeks, eyeliner (kohl), eyeshadows, and foundation […] In Mesopotamia, pots of colored paints for the eyes, and rouges for the lips have been found in Sumerian tombs near Ur from 5,000 years ago.

[…] Excavations at Harappa and Mohenjo-daro have found kohl pots and sticks for lining the eyes, as well as red iron oxides and white lead-based compounds that have been surmised to be rouge for the lips and cheeks and foundation for lightening the skin […] Evidence for ancient uses of received cosmetics in the East Asia is less clear, though there is a long history of the use of white face paint and rouge for the lips in China and Japan (Corson, 1972). Overall, there is evidence for the idea that the received style of cosmetics developed in multiple centers of early technology development, and spread outward to peripheral areas such as Europe and Southeast Asia, analogous to the spread of other technologies like agriculture and writing. (Russell, 2010)

This contrast effect may have likewise influenced evolution within our species. The most common human phenotype combines relatively light skin with dark hair and dark eyes. The opposite pattern is biologically possible but rare. In addition, the whitening of European skin might have provided a sufficient degree of luminous contrast for hair and eye color to diversify.

Not just luminous contrast

Facial contrast involves differences not only in luminosity, i.e., lightness/darkness, but also in hue, particularly the redness of the lips versus the lack of ruddiness of adjacent facial skin. Contrast in luminosity and hue declines with age and may provide a means for distinguishing younger from older women:

Several aspects of facial contrast – the luminance and color differences between the facial features and the skin surrounding those features – were found to decrease with age. These included the luminance contrast around the eyes and eyebrows, the red-green (a*) contrast around the mouth and eyes, and the yellow-blue (b*) contrast around the eyes. (Porcheron et al., 2013)

Hue contrast explains why redness—lipstick, red clothing, etc.—seems to enhance femininity even though women are the less ruddy sex. Red colors highlight this lack of ruddiness, thereby stimulating the mental algorithm that people use for sex recognition:

Stephen & McKeegan [26] found that people increase the redness (a*) of the lips to make a female face appear more feminine and attractive. Elliot & Niesta [46] found that pictures of women are perceived by men as more attractive and sexually desirable when they are associated with the color red–whether by the placement of a red border around the picture, or the presence of a red colored shirt on the woman. (Porcheron et al., 2013)

Some questions remain unanswered. Why, for instance, do many women redden their cheeks? Are the cheeks a secondary contrast zone? And what about women from racial groups with dark facial skin?

This last question seems to have given the study’s authors some trouble with the reviewers. Evidently, darker-skinned women still have some facial contrast. They just don’t have as much, probably because they don’t need as much. Dark skin tends to characterize highly polygynous societies; in fact, the correlation between darkness of skin and polygyny rate is greater than the one between lightness of skin and latitude (Manning et al., 2004). In such societies, women are almost sure to get mated and remain so as long as they are fertile. There is thus only weak selection for those who can better attract potential mates and more strongly stimulate sex-recognition algorithms. 

On a final note, it’s no coincidence that the polygyny rate correlates inversely with latitude. In simple tropical societies, especially those with year-round farming, women can more easily provide for themselves and their children without male assistance. Since women cost so little to support, men will tend to seize all mating opportunities. A man will have as many wives as he can get, and not as many as he can support.

 

References

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. http://journalofvision.org/9/2/10/ 

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

http://onlinelibrary.wiley.com/doi/10.1002/aja.1000650102/abstract;jsessionid=43509EAC6110062BBF5676995DA16C6B.d01t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false 

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.

http://endo.endojournals.org/content/28/1/119.short 

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

http://www.ehbonline.org/article/S1090-5138(03)00082-5/abstract 

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

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0057985 

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

http://public.gettysburg.edu/~rrussell/Russell_SocialVision_cosmetics_chapter.pdf 

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

http://public.gettysburg.edu/~rrussell/Russell_2009.pdf