Waist–hip ratio
The waist-hip ratio or waist-to-hip ratio (WHR) is the dimensionless ratio of the circumference of the waist to that of the hips.
This is calculated as waist measurement divided by hip measurement (W ÷ H). For example, a person with a 30″ () waist and 38″ () hips has a waist-hip ratio of about 0.78.
Devendra Singh
A pioneer in the field of evolutionary psychology, Singh's most notable research concerned the evolutionary significance of waist-to-hip ratio (WHR). In 1993, he was the first to elucidate the concept and significance of this ratio as an indicator of attractiveness. In brief, Singh discovered that men rated women with low WHR (0.7) as optimally attractive, noting that lower levels of WHR correlated to lower risk of disease and greater fertility. Subsequent research demonstrated the cross-cultural and cross-temporal appeal of a low WHR. One of his final research papers on the topic of WHR found that the "hourglass figure" (optimal WHR) activates brain centers that drive appetitive sociality/attention toward females that represent the highest-quality reproductive partners.