This entry was written by Geoff Kushnick as part of a project done in BIAN 2133 ‘Human Reproductive Strategies’ at The Australian National University in 2019 Semester 2.
Introduction
Because it contains information about aspects of potential mates that impinge upon fitness, foot size relative to height may have evolved as a mate choice cue. Males may prefer women with small feet because they are more nubile (i.e., they are younger and have not yet experienced pregnancy), whereas females may be relatively more indifferent to this cue. This idea has been tested by looking at sexual dimorphism in skeletal samples, as this should be one of the outcomes driven by sexual selection when there is persistent mate choice for a particular trait. It has also been tested using mate choice experiments. The results of the former are reasonably consistent, but the results of the latter show quite a bit of variability.
In this entry, I will provide a brief overview of these studies and their results, as well as some discussion of the limitations of the evolutionary psychology approach to the relationship between foot size and mate choice.
Main Text
Nubility Hypothesis and Foot Size
Evolutionary psychologists have argued that, because they faced very different selective pressures in the past (i.e., the ‘environment of evolutionary adaptedness’), men and women should have divergent mate choice criteria (Conroy-Beam et al, 2015). While women’s fitness may have benefitted from choosing mates that had the greatest ability to acquire resources, men may have done so by choosing the most nubile mates. The nubility hypothesis posits that the male cognitive machinery for mate choice has evolved to find women most attractive who show signs (aka ‘cues’) of being at the peak of their reproductive career (Symons 1979).
Barber (1995) reviewed mate choice criteria related to a wide range of human anatomical features. He pointed to feet as being a potential cue related to attractiveness in females for reasons akin to those set forth in the nubility hypothesis. Women’s feet may be a useful cue of nubility as they get bigger, relative to height, as a women ages and has children (Fessler et al, 2005a,b).
Foot Size Sexual Dimorphism
If there has been persistent mate choice for small feet for body size, it would drive sexual selection on foot size, leading to sexual dimorphism. Fessler et al (2005a) explored sex differences in foot size relative to height, reviewing previous studies on 32 skeletal populations, and conducting new analyses on genetically-variable populations of US Army recruits of genetically diverse origin (i.e., some were Native American, some were white American, etc). They found that the length of the female foot was shorter in proportion to height than in males, and that this pattern was consistent across the populations studied. They explored the idea that natural selection could have been a force in shaping foot size and shape in humans but preferred a sexual selection-based explanation.
Cross-Cultural Research
Fessler et al (2005b) conducted a cross-cultural test of the idea that there should be universal preference by men for women with relatively shorter feet for height, while women should prefer men with intermediate-size feet for height. They presented both male and female respondents with randomly ordered line drawings of women (female stimuli) that were identical except in foot length and then asked them to choose the one they found most attractive and least attractive. They then did the same things with line drawings of men (male stimuli). The experiment was carried out in Iran, India, Russia, Tanzania, Lithuania, Brazil, USA, Papua New Guinea, and Cambodia. They found that, as predicted, the most attractive female stimuli were the ones with the smallest feet; the least attractive were the ones with the largest feet (Fessler et al 2005b). Also, as predicted, they found that male stimuli with intermediate-sized feet were rated as the most attractive; the relatively larger and smaller feet were rated as the least attractive.
Kushnick (2013) argued that the disaggregated samples suggested that there was a considerable amount of variation in foot-size preference in the populations studied. For instance, although, Iran, Lithuania, Brazil, USA, and India had a clear preference for women with small feet, Cambodia, Karo, Papua New Guinea, and Tanzania preferred women with large feet. Adding a new sample from North Sumatra, Indonesia, from amongst a rural agricultural population known as the Karo, he conducted some simple tests of alternative hypotheses that might explain the variation. The first hypothesis was that cultural evolutionary forces might have driven a small-foot preference. The second hypothesis was that rural environments would lead to a preference for large-feet in potential wives as they would indicate that the potential spouse would be better fit for doing the sorts of subsistence tasks appropriate in those environments. The third was that patriarchal values would lead to a preference for inconveniently small feet.
Using contingency table analysis, Kushnick (2013) found the following: Strong support the hypothesis that small-foot preference was associated with access to Western media; medium-level support for the hypothesis that rural environment was associated with large-foot preferences; and no support for the idea that patriarchal values was associates with small-foot preferences. The results question the usefulness of some central concepts of evolutionary psychology and suggest that looking at more recent adaptation to modern environments (biologically and culturally) might be useful in understand the relationship between foot size and attractiveness.
Conclusion
Foot size relative to height is of intense interest to evolutionary psychologists, as it is a trait that provides information about the reproductive potential of a prospective female mate (i.e., her age and reproductive history). Studies of skeletal populations have shown that there is indeed consistent sexual dimorphism in the populations studied. Further, there is some support that small feet in women is considered attractive, though it is not consistent across the populations studied. Studies of the correlates of small-foot preference suggest that cultural and biological evolution has led to variable reproductive and adaptive strategies with regard to foot size and attractiveness.
Literature Cited
Barber, N. (1995). The evolutionary psychology of physical attractiveness: Sexual selection and human morphology. Ethology and Sociobiology, 16, 395-425.
Conroy-Beam, D., Buss, D., Pham, M.N., & Shackelford, T.K. (2015). How sexually dimorphic are human mate preferences? Personality and Social Psychology Bulletin, 41(8), 1082-93.
Fessler, D. M. T., Haley, K. J., & Lal, R. D. (2005a). Sexual dimorphism in foot length proportionate to stature. Annals of Human Biology, 32(1), 44-59.
Fessler, D. M. T., Nettle, D., Afshar, Y., Pinheiro, I., Bolyanatz, A., Borgerhoff Mulder, M., … Zbarauskaite, A. (2005b). A cross-cultural investigation of the role of foot size in physical attractiveness. Archives of Sexual Behavior, 34(4), 267-276.
Kushnick, G. (2013). Why do the Karo Batak prefer women with big feet? Flexible mate preferences and the notion that one size fits all. Human Nature, 24(3), 268-279.
Symons, D. (1979). The evolution of human sexuality. Oxford: Oxford University Press.