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The news that Angelina Jolie had a double mastectomy got a lot of attention. Both beauty and cancer are produced by sex hormones. Perhaps there is a biological tradeoff between exceptional beauty and health.
Charles Darwin concluded that male animals evolve “ornaments” that function to charm females of the species. He was thinking of brilliant plumage displays such as the tail feathers of a peacock. Women are more ornamented by sexual selection than men (although beards can enhance men's attractiveness [1]). Women’s sexually selected ornaments include permanently enlarged breasts, narrow waist, rounded facial features, shortened feet and hands, and much else.
Darwin knew that sexual ornaments facilitate successful mating but he also recognized that they are potentially costly. Brightly-colored birds are conspicuous to predators, for instance, which is why the females of most species are duller, or more cryptic, than the males.
The hidden cost of sexual attractiveness
Sexual signals develop at puberty under the influence of sex hormones. The amplitude (intensity) of the signal is determined by the amount of hormone secretion. This means that women producing high estrogen levels are unusually curvaceous and very sexually attractive. High testosterone men are stronger and more stereotypically masculine.
Yet, there are limits to how sexy a woman’s body may be. In subsistence societies where the diet has a lot of fiber, women cannot afford to have waists that are too narrow or they might experience malnutrition. Researchers discovered that wider waists are perceived as more physically attractive in these societies than is the case in our own [2].
So there are practical constraints on how exaggerated a bodily sexual signal may be. This might help to explain why the majority of women do not have the extremely slender waist-to-hip ratio (less than 0.7) that is characteristic of a beauty queen with a 24-inch waist and 36-inch hips.
In addition to practical constraints on bodily evolution, there may also be biological limitations. An extremely curvy body can be produced by increasing the amount of estrogens secreted into the body with sexual maturation.
Doing so generally increases health, and fertility, as well as physical attractiveness. Unfortunately, increased production of sex hormones is also a risk factor for breast cancer just as high testosterone is a risk for testicular cancer in men [3]. We do not know the details in Ms. Jolie’s case but it is at least possible that her biological predisposition to beauty was also implicated in her genetically elevated cancer risk.
Most women do not look like actresses or beauty queens, however. Yet, they seem to have no trouble finding dates.
Seinfeld’s enigma
This apparent contradiction can be christened “Seinfeld’s enigma.” The comedian claimed that a large majority of the population is “undatable.” Yet, he recognized that people are nevertheless getting together.
That is the enigma. Seinfeld’s celebrated solution to his own enigma was “alcohol.”
A more likely explanation is that despite not looking like beauty queens, most women are nevertheless sufficiently attractive to most men. It may be that physical attractiveness is only one aspect of mate value and not a decisive one. That seems unlikely in view of research indicating that physical attractiveness matters a lot [1].
More likely, physical attractiveness is the sum total of many different qualities and traits that include voice quality, skin quality, stature, symmetry, youthfulness, fragrance, posture, and so on.
Non beauty queens may be very attractive despite not having exaggerated sexually-selected traits such as narrow waists. Not having such elaborate body signals may indicate that they are somewhat less fertile. They may also be more prone to heart disease and other health problems [1].
On the other hand, less curvy women may have a lower risk from some cancers. So men may be selected to mate with average-looking women after all and the same principle may work for women’s choice of men. An average-looking man may be preferred to an athlete with bulging muscles. That, rather than alcohol, could be why they are getting together.
1. Barber, N. (2002). The science of romance. Buffalo, NY: Prometheus.
2. Weisman, A., & Marlowe, F. (1999). How universal are preferences for female waist-to-hip ratios? Evidence from the Hadza of Tanzania. Evolution and Human Behavior, 20, 219-223.
3. Clemons, M. B., and Goss, P. (2001). Estrogen and the risk of breast cancer. The New England Journal of Medicine, 344, 276-286.
