Abstract:
A fundamental assumption of adaptive explanations of female attractiveness is that bodily features that males judge as attractive reliably signal youthfulness, healthiness, and fertility or female mate value. One of the bodily features, waist-to-hip ratio (WHR), is a reliable indicator of a female's reproductive age, sex hormone profi le, parity and risk for various diseases. Systematic variation in the size of WHR also systematically affects the judgment of female attractiveness, healthiness, and youthfulness. This article summarizes recent fi ndings about the relationship between female's WHR and various factors affecting reproductive capability and risk for diseases. Research on the relationship between attractiveness and WHR is discussed in light of some methodological objections to previous research. Finally, cross-cultural and historical data are presented that suggest that the relationship between WHR and female attractiveness is not culture-specifi c and not inculcated by modern Western fashion dictates or media.

Excepts

Introduction: General Characteristics of WHR: Overall body weight gain is the most noticeable change caused by pubertal onset in women. The most popular technique for estimating body weight is body mass index [BMI (weight in kilograms divided by height in meters squared)]. The increase in BMI observed in women during puberty does not take into account the sex-dependent anatomical distribution of fat deposits . The deposit and utilization of fat from various anatomical areas is regulated by sex hormones. Simply stated, estrogen inhibits fat deposit in the abdominal region and maximally stimulates fat deposit in the gluteofemoral region (buttocks and thighs) more in than any other region of the body. Testosterone, in contrast, stimulates fat deposit in the abdominal . It is this sexually dimorphic body fat distribution which primarily sculpts typical body shape differences between the sexes that becomes noticeable after pubertal onset; women have greater amounts of body fat in the lower part of the body (gynoid body fat, or pear shape), whereas men have greater amounts of fat in the upper body (android body fat, or apple shape). This sexually dimorphic body fat distribution is most commonly quantifi ed by measuring and computing the ratio of the waist to hips (WHR) circumference. WHR has a bimodal distribution with relatively little overlap between the sexes [18]. The range of WHR for the healthy premenopausal Caucasian women has been shown to be 0.67-0.80 and in the range of 0.85-0.95 for healthy Caucasian men [19]. Women typically maintain a lower WHR than men throughout adulthood, although after menopause WHR approaches the masculine range. The increase in the size of WHR in menopausal women is due to the reduction of estrogen levels.
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WHR and Attractiveness Judgments: To establish that WHR allows males to solve the adaptive problem of identifying a female's mate value, it needs to be demonstrated that males possess perceptual mechanisms to detect and use information conveyed by WHR in determining a woman's attractiveness as a potential mate. If this is so, it should be possible to systematically change men's evaluations of women's attractiveness by manipulating the size of WHR alone. To investigate this issue, I developed 12 drawings of female fi gures, differing solely in the size of their WHR. As there is a positive relationship between BMI and WHR, I used three levels of BMI (underweight, normal and overweight). Within each weight category, line drawings represented four levels of WHR [two typical gynoid WHR (0.7 and 0.8) and two android (0.9 and 1.0) by changing waist size only. The choice to represent various WHRs by changing the size of the waist was based on fi ndings that of all body parts, waist size is clearly positively correlated with altered sex hormonal profi le. For instance, postmenopausal women on hormone replacement therapy loose fat selectively from the waist without any signifi cant change in fat deposit on the hip, buttocks or overall body fat Judgments of attractiveness, healthiness and youthfulness were obtained for these 12 figures from men and women of diverse age (18-85 years old), professional (white collar workers, lawyers, physicians), educational (undergraduates and postgraduate degree), and ethnic (Afro-American, Mexican American, Euroamerican) backgrounds. To summarize the findings: a) there was a high degree of consensus across sex, educational and ethnic background for the judgment of attractiveness, healthiness and youthfulness; b) participants judged figures with gynoid WHRs (0.7 and 0.8) as more attractive, healthy, and youthful than figures with android WHRs (0.9 and 1.0); and c) attractiveness ratings along with ratings of healthiness and youthfulness show a linear drop from WHR of 0.7, followed by 0.8, then 0.9 and then 1.0 in each body weight category.
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Cross-generational (historical) Evidence:
  • • •   One way to assess the role of cultural diffusion versus adaptive design for cross-cultural consensus in attractiveness is to examine the ancient sculptures of various cultures.   • • •   If it can be demonstrated that ancient Greek (Greco- Roman), Indian and Egyptian sculptures depict a sexually dimorphic WHR, such a consensus cannot be explained by the infl uence of modern Western culture. To explore this possibility, I measured WHRs in 286 ancient sculptures from India, Egypt, Greece (Greco- Roman) and some African tribes. In all four cultural groups, distributions of WHR vary but the mean female WHR was signifi cantly lower than the mean male WHR, despite cultural variability (Figure 3 here). Hence, it follows that evolved preferences for female WHR may not be for any absolute size, but rather for lower than average male WHR size evident in a given population.
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General Discussion & Conclusions:
The research summarized in this article validates the assertion that selection designed psychological mechanisms in humans to attend to bodily features that convey reliable information about phenotypic and genetic quality and to judge such bodily features as attractive. WHR is a reliable indicator of a woman's various aspects of reproductive capacity (postpubertal premenopausal status, hormonal status and probability of conception and parity), early sign of pregnancy, potential parasite infestation and risk for various diseases. Given that WHR is a heritable trait, an ancestral man selecting a mate with low WHR would have assured his offspring of high quality maternal care (lower risk for diseases) and the genetic gift of good health.

It could be the link between phenotypic quality and WHR that explains the appeal of an hour-glass fi gure with full breasts and wider hips set against a narrow waist. Women seem to know that the hour-glass fi gure is sexually appealing to men and attempt to highlight it by manipulating their waist size. When asked how they embellish their appearance around men, young women in the U.S. report “sucking in” their stomachs as the most frequently used tactic after facial makeup and clothing. Similarly, the past popularity of the corset, in spite of the internal injury it caused women, and the currently popularity of abdominoplasty (tummy tuck) are testimonials of the importance of waist size in defi ning a sexually attractive body. Alternately, women who wish to conceal their sexual attractiveness, such as executive businesswomen, choose clothing that hides rather than highlights their body shape. Nuns' habits, for example, disguise WHR and send a message to males that the women inside the costume are not potential sexual mates.   • • •