One of the main problems facing our hunter-gatherer ancestors during the Pleistocene epoch, say evolutionary psychologists, was the identification of mate value. Singh (1993a) proposed that, to overcome this problem, ‘perceptual mechanisms’ or mental modules evolved in men to detect the information conveyed by the waist-to-hip ratio (WHR) in determining a woman’s attractiveness as a potential mate.Because of its association with health and fertility outcomes, men will have evolved to use the WHR as a direct assessment of women’s underlying quality. And so, Singh argued, it should be possible to systematically change men’s evaluations of women’s attractiveness by manipulating the size of the WHR.To test this idea, Singh developed a set of 12 line drawings of the female figure, which were systematically varied with respect to overall body weight and the WHR levels of the WHR by changing the waist size. In a series of experiments using these drawings, Singh described negative correlation between WHR and female attractiveness. That is, line drawings with gynoid WHRs (0.70 and 0.80) were judged as the most attractive, and ratings decreased with increasing WHR.MORE: Body Shape and Attraction Using Singh’s original set of line drawings, the preference for low WHRs has been replicated with participants in the United States, Britain and Germany. But lest it be that line drawings do not reflect actual mate preferences as they occur in life, studies have also examined the effect of WHR in field studies with people. VIDEO: Interpreting your Waist Measurement Mikash and Bailey (1999) reported that women with low WHRs have more sexual partners than women with high WHRs, whereas Hughe and Gallup (2003) found that young women with low WHRs also report earlier ages of first intercourse. In addition, aesthetic plastic surgery that redistributes body fat to make the body more proportionate without altering BMI appears to increase ratings of attractiveness.In combination, these studies indicate that, to be considered attractive, a woman should have a low WHR and fall within the normal body weight range. Some researches have even gone so far as to suggest that dieting is a ‘natural’ strategy employed by women attempting to achieve the ideal WHR. While Singh’s research was framed in terms of the comparison of low WHR to high WHRs, some evolutionary psychologists have suggested a specific preference for a WHR of 0.70.