Essay:Human mating strategies and sexual preferences

Male Sexuality

Standards of Female Preference

Waist-Hip Ratio

Singh (1993) has reported that men tend to have a preference for women with a waist to hip ratio (WHR) centering near 0.70. The possible reasons are varied.

Body-fat distribution is both highly heritable (between 0.2 and 0.5) and under the control of hormones. The "gynoid", or lower body fat accumulation differentiating men and women is principally the result of pubescent hormonalization; estrogen concentrating fat around the buttocks and thighs, androgens (testosterone in particular) in the abdominal region. Because gynoidal differences are absent until puberty and are typically maintained until menopause, Singh argues that WHR can be viewed as a reliable marker of age (see Youthfulness below).

WHR is also potentially an independent criteria of fertility. Zaadstra et al (1993), based on a large study of Dutch women (N = 542), found that

A 0.1 unit increase in waist-hip ratio led to a 30% decrease in probability of conception per cycle (hazard ratio 0.706; 95% confidence interval 0.562 to 0.887) after adjustment for age, fatness, reasons for artificial insemination, cycle length and regularity, smoking, and parity.

That is, a woman with a WHR of 0.80 instead of Singh's "optimal" 0.70 would have a 30% lower chance of becoming pregnant, regardless of age or total weight. Furnham et al (1998) also report that WHR can predict a number of potentially life-threatening illness, including diabetes, hypertension, heart attack and endometrium cancer, all of which weigh heavily on issues of fertility.

Freese & Meland (2002), however, could not replicate Singh's findings. Drawing on a larger, obtensibly more accurate sample from the Atlantic City Newspaper accounts of Miss America Pagent contests (Singh's source, Bivans, is reported to have rounded measurments to the nearest half-inch), the authors conclude that

For the Miss America sample, the WHR of winners have ranged from 0.61 (Mayer, winner in 1963, W = 22/H = 36) to 0.78 (Gorman, winner in 1921, 25/32). (4) Only 9 of the 59 winners have WHRs between 0.69 and 0.72 (15%). The median for the Miss America sample is 0.667. The mean WHR value is not 0.70, as someone reading Buss (1999) or Buss and Kenrick (1998) might think, but in fact the mean is significantly less than 0.70 (mean=0.677, t=-4.89, p<0.001).

One could protest that the difference between 0.70 and 0.677 is substantively small, even if statistically significant. We do not necessarily disagree, but we also believe that evolutionary psychological writings on WHR do not give one much sense of how the magnitude of differences in WHR should be substantively regarded. In the face of repeated assertions that the WHR of beauty icons seems to cluster invariably and tightly around 0.70--as well as that the evolved WHR preference is tuned precisely to 0.70 as the optimum (e.g., Alcock, 2001)--a statistically significant difference in a sample of modest size would seem substantively consequential.

Freese & Meland's study, however, does nothing to invalidate other conclusions in Singh (1993), including modern WHR preferences derived from line drawings shown to college students, which have alternatively been verified (Furnham et al, 1997), and independently refuted (Henss, 1995).

Recently, some researchers have argued that Body Mass Index (BMI) is a more appropriate body-type criterion in male sexual preferences. Tovee et al (1999), contra the arguments presented by Singh (1993), present research showing that BMI is a much stronger cue for physical attractiveness than WHR. They claim their disparate conclusions are the result of the line drawings used in the study alluded to above: in all three studies, BMI is said to be held constant, with the only variation occuring in WHR. However, because the series of figures is altered by changing the width of the torso around the waist, the perceived BMI is consequently distorted in such a way that the two measures, WHR and BMI, covary. That is, in both Singh (1993) and Furnham et al (1997), as WHR was increased in the figures presented to test subjects, so too was BMI. Additionally, because Tovee et al's own study on male college students used pictures of real women, both WHR and BMI were precisely known, and their effects can be estimated separately.

Additionally, BMI is also reported to be more strongly linked to fertility and health. Not only is BMI consistant with the results of Zaadstra et al (1993), but Manson et al (1995) found that the mortality of women in a large cohort study was lowest in those with a BMI near 19, the attractive optimal according to Tovee et al. Lake et al (1997) and Brown (1993) also find that elevated BMI values are responsible for factors like menstrual problems, hypertension in pregnancy and subfertility.

Youthfulness

While important in the preferences of both sexes, age is a particularly important criterion in standards of female attractiveness. Cross cultural anthropological records conclusively demonstrate that men, more than women, place a particular emphasis on the age of potential sexual partners (Symons, 1979; Buss, 1985, 1987, 1989). Quinsey et al (1993), for example, observed that men find young adult and pubescent females about equally attractive, while women found pubescent males unattractive. Viewed in evolutionary terms, those men who had such a preference for youth in the past would tend to out-reproduce those fixated on post-reproductive aged, or pre-pubescent females, to the extent that age is a reliable phenotypic marker of potential fertility.

Perhaps more interestingly, male age preferences in women actually decrease as they themselves grow older; that is, the older a man gets, the more likely he is to be sexually attracted to younger and younger females. Eisenmann (2002) suggests that:

As the man ages, he fears that his genes will not be as good. Just as men in general desire youth, attractiveness, and health in their female partners, so that their genes will be good ones and will be spread into future generations, so too the aging man seeks this. But, he seeks it even more so than usual, as he fears, perhaps unconsciously, that his genes are not as good now as they once were. To make up for this, his partner must have excellent genetic potential. The way to achieve this is to balance his aging with her youth.

Breast Size and Shape

The extent to which any female breast size is preferred by men is a contentious issue among scientists. Between the relatively few studies attempting to isolate one preference over another, conclusions have ranged from a male (and female) preference for medium sized breasts (Kleinke and Staneski, 1980) to a male preference for larger breasts on slim women and a female preference for smaller breasts on the same (Gitter et al, 1983; see also the review in Furnham et al, 1998). Singh and Young (1995) and subsequently Furnham et al (1998) found that, rather than being an independent criterion of sexual attractiveness, the desirabily of any particular breast size was a function of both total body weight and the waist-hip ratio (see Waist-Hip Ratio above).

There is, additionally, the reason why men prefer breasts at all. As most mammals lack enlarged breasts except during lactation (Ford and Beach, 1951) it is necessary to provide a positive account of said preference's development. Low et al (1987) has argued that enlarged breasts were initially selected for on the basis of milk provision to potential offspring, but because men were unable to distinguish between breasts enlarged by fat and those enlarged by glandular tissue, fat was selected for. Smith (1986) has argued that breasts function as a sort of cushion for children, thereby signalling mothering ability to men indirectly. Miller (1995) has argued for a round-about scenario whereby resource provisioning during lactation becomes more generous because of the benefits that crucial period bestows on children. Together with the dominant male aversion to visible breasts alluded to above (and by extension, the courting of larger-breasted women by non-dominant males), women with enlarged breasts were better provisioned, and therefore women with genes for larger breasts left more descendants. Morris (1967) once argued the enlargement of female breasts compared to other apes as mere sexual signaling devices and fundamentally associated the signal to estrous swelllings on female apes.

These hypotheses aside, there is of yet no clear cut explanation.

Female Sexuality

Standards of Male Preference

The following is a list of traits women look for when choosing a male partner.

Status and Resources

Besides obvious biological and time consideration, the number of offspring a woman can mother is restrained by the resources available to her. To the extent that men affect these resources, women are expected to have evolved a desire for men with the most or the best (Emlen and Oring, 1977). Buss (1985, 1987, 1989) found that a desire for men with resources is a female universal, a preference much stronger in women than in men regardless of the culture under consideration. Indeed, for all species with the appropriate social systems, this general pattern seems to hold true (Rubenstein and Wrangham, 1986). It may be suggested that this reflects covariation with some other aspect of sexual dimorphism or human culture, i.e., women are economically dependent of men because of past injusticies, because men are physically able to command the resources, etc. However, Widerman and Allgeier (1992) have observed that, far from disappearing, economically independent women actually have a stronger preference for men with resources.

Intelligence

"Intelligence" as measured by IQ and other mental tests is a relativly pure measure of g (Jensen, 1980, 1998), and is the single best predictor of various social outcomes, including educational variables and socio-economic status, which in adulthood, can reach as high as r = .70. Interestingly, high IQ males in tribal societies are almost invariably among the leaders (Brown, 1991). For this reason, female preference for wealthier, higher status men is expected to covary with IQ; that is, women should have been shaped by evolution to desire higher IQ men, not for IQ per se, but as a proximal cue for resources and status. According to Buss (1994), "intelligence" is ranked fifth of all desirable attributes worldwide, with 10 out of 37 societies having a stronger preference for high IQ in women than in men (in the others, the preference is equally strong).

Bilateral Symmetry

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Sexual Jealousy

Evolutionary theory explains the different ways in which males and females experience sexual jealousy. The greatest worry for a man would be the sexual infidelity of the mate he has invested in because he may not be the biological father of the children he is supporting. Meanwhile, a woman's greatest threat is the emotional infidelity of her mate. If her mate bonds with another woman, resources may have to be shared or worse, transferred to the other woman and her offspring. From a biological point of view, this makes emotional infidelity more dangerous for a woman than mere sexual infidelity.

References

Brown, D.E. 1991. Human universals. Philadelphia: Temple University Press.

Brown, J. 1993. Preconceptional nutrition and reproductive outcomes. Annals of the New York Academy of Sciences, 678: 286-292.

Buss, D. 1985. Human mate selection. American Scientist, 73: 47-51.

Buss, D. 1987. Sex differences in human mate preferences: An evolutionary persepective. In Sociobiology and Psychology, ed. C. Crawford et al. Erlbaum.

Buss, D. 1989. Sex differences in human mate preferences: Evolutionary hypothesis tested in 37 cultures. Behavioral and Brain Science, 12: 1-14.

Buss, D. 1994. The evolution of desire. New York: Basic.

Emlen, S. and L. Oring. 1977. Ecology, sexual selection and the evolution of mating systems. Science, 197: 215-222.

Ford, C. and F. Beach. 1951. Patterns of Sexual Behavior. New York: Harper & Brothers.

Freese, J. and S. Meland. 2002. Seven tenths incorrect: heterogeneity and change in the waist-to-hip ratios of Playboy centerfold models and Miss America pageant winners. Journal of Sex Research, May 2002.

Furnham, A. et al. 1997. Waist-to-hip ratio and preferences for body shape: A replication and extension. Personality and Individual Differences, 22: 539-549.

Furnham, A. et al. 1998. The role of body weight, waist-to-hip ratio, and breast size in judgements of female attractiveness. Sex Roles: A Journal of Research, Aug 1998.

Gitter, A. et al. 1983. Perception of female physique characteristics by American and Israeli students. Journal of Social Psychology, 121: 7-13.

Henss, R. 1995. Waist-to-hip ratio and attractiveness: A replication and extension. Personality and Individual Differences, 19: 479-488.

Jensen, A.R. 1980. Bias in mental testing. New York: The Free Press.

Jensen, A.R. 1998. The g factor: the science of mental ability. Westport: Praeger.

Kleinke, C. and R. Staneski. 1980. First impressions of female bust size. Journal of Social Psychology, 110: 123-134.

Lake, J. et al. 1997. Women's reproductive health: The role of body mass index in early and adult life. International Journal of Obesity, 21: 432-438.

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Manson, J. et al. 1995. Body weight and mortality among women. New England Journal of Medicine, 333: 677-685.

Morris, Desmond. 1967. The Naked Ape: A Zoologist's Study of the Human Animal.

Quinsey et al. 1993. The phylogenic and ontogenetic development of sexual age preference in males: Conceptual and measurment issues. In The Juvenile Sex Offender, ed. H. Barbaree et al. Guilford.

Rubenstein, D. and R. Wrangham. 1986. Ecological aspects of social evolution: Birds and mammals. Princeton University Press.

Singh, D. 1993. Adaptive significance of female physical attractiveness: Role of waist-to-hip ratio. Journal of Personality and Social Psychology, 65: 293-307.

Singh, D. and R. Young. 1995. Body weight, waist-to-hip ratio, breasts, and hips: Role in judgments of female attractiveness and desirability for relationships. Ethology and Sociobiology, 16: 483-507.

Symons, D. 1979. The evolution of human sexuality. Oxford University Press.

Tovee, M. et al. 1999. Visual cues to female physical attractiveness. Proceedings of the Royal Society of London B, 266: 211-218.

Wiederman, M. and E. Allgeier. 1992. Gender differences in mate selection criteria: Sociobiological or socioeconomic explanation? Ethology and Sociobiology, 13: 115-124.

Zaadstra, B. et al. 1993. Fat and female fecundity: Prospective study of effect of body fat distribution on conception rates. British Medical Journal, 306: 484-487.

Acknowledgments

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