Assessment of Waist-to-Hip Ratio Attractiveness in Women: An Anthropometric Analysis of Digital Silhouettes

Krzysztof Koscin ski 0 1 0 K. Koscinski (&) Institute of Anthropology, Faculty of Biology, Adam Mickiewicz University , Umultowska 89, 61-614 Poznan, Poland 1 Waist-to-hip ratio Attractiveness Preference The low proportion of waist to hip size in females is a unique and adaptive human feature. In contemporary human populations, the waist-to-hip ratio (WHR) is negatively associated with women's health, fecundity, and cognitive ability. It is, therefore, hypothesized that men will prefer women with low WHR. Although this prediction is supported by many studies, considerable disagreement persists about which WHR values are the most attractive and the importance of WHR for attractiveness of the female body. Unfortunately, the methods applied thus far are flawed in several ways. In the present study, we investigated male preferences for female WHR using a high precision assessment procedure and digitally manufactured, high quality, anthropometrically informed stimuli which were disentangled from body mass covariation. Forty men were requested to choose the most attractive silhouette consecutively from six series (2 levels of realism 9 3 levels of body mass), each consisting of 26 female images that varied in WHR (from .60 to .85 by .01). Substantial inter-individual variation in the choices made was observed. Nevertheless, low and average WHR values were chosen more frequently than above-average values or values below the normal variation of the trait. This preference pattern mirrors the relationship between WHR and mate value, suggesting that the preferences are adaptive. - The low ratio of waist to hip size in females is a unique human feature (Singh, 1993) and several adaptive mechanisms might have contributed to its evolution. First, the human newborn has a relatively large head and a large pelvis facilitates its delivery (Rosenberg, 1992). Second, a narrow waist is a visual cue of the absence of pregnancy and therefore current fecunditya feature that ancestral men sought in women. This may be an especially important cue in humans because women do not signal their present fertility in any other easily perceptible way (Singh, 1993). Third, fat, when deposited around the hips rather than the waist, facilitates bipedal stability of pregnant and lactating women (Pawowski & Grabarczyk, 2003), contains fatty acids beneficial for brain development of the fetus and infant (Lassek & Gaulin, 2008), and may dishonestly signal a broad pelvis and absence of pregnancy so as to make the woman attractive to men (Furnham, Mistry, & McClelland, 2004; Low, Alexander, & Noonan, 1987). In contemporary human populations, waist-to-hip ratio (WHR) is negatively related to the level of estradiol and positively related to the level of testosterone, which is why WHR is clearly lower in women than men (see literature cited in Singh & Singh, 2011). High WHR values in women are associated with mortality and many medical conditions, such as cardiovascular diseases, type 2 diabetes, gall bladder disease, lung function impairment, carcinomas, menstrual irregularity, anovulatory cycles, and subfertility (as reviewed in Singh & Singh, 2011; World Health Organization, 2011). According to sexual selection theory (Kokko, Brooks, McNamara, & Houston, 2002), these would have driven the evolution of male preference for low-WHR women which, in turn, would become another selective factor for low WHR. Although preference for low WHR was indeed found in most studies of industrial and traditional societies (reviewed in Singh & Singh, 2011), large inconsistency exists as to the most attractive value of WHR. Even if we limit our focus to populations of European descent, the values range from .5 (Heaney, 2000; Schu tzwohl, 2006), which is far below the normal range of the trait (see below) to .8, which is somewhat above the average (Henss, 1995), or even higher values (Furnham, Swami, & Shah, 2006). A more precise determination of the most attractive WHR would allow for the establishment of the type of sexual selection that acts on the body characteristic: whether the preference is for values close to the mean (.70.75; stabilizing selection), below-average but within the range of normal variation (about .65; directional selection), or below the normal range (.60 or less; strongly directional selection). It would also facilitate confirmation of whether the preferred WHR values are those associated with good health (i.e., values somewhat below the average) or not (i.e., average, above-average or extremely low values) (Lassek & Gaulin, 2008; Riordan, 2007; Singh & Singh, 2011; Wass, Waldenstro m, Ro ssner, & Hellberg, 1997). Because previous research has not answered the question, further investigation is warranted. The chief reason for inconsistency in results of previous studies seems to be methodological diversity and, in particular, the stimuli to be assessed. These include schematic drawings of females varying in WHR (e.g., Singh, 1993; Tassinary & (...truncated)