[Image][Image] [Image][Image] [Image] [Site Navigator][Home][Contact Us][Image] [Image] [Image] [Image] [Image] [Image] [Image] [Image] [Image] The Shape of Beauty: In the Eye of the Beholder? by David B. Miller, University of Connecticut © 1999 Peregrine Publishers, Inc., All Rights Reserved "Beauty is in the eye of the beholder," says [Image] the old adage. But is beauty or attractiveness entirely subjective, as this saying seems to imply? Or are there invariable characteristics that most people find attractive? Scientists believe that specific regularities underlie how we go about selecting friends andămore important from an evolutionary perspectiveămates. Charles Darwin posited the concept of sexual selection to indicate that there are some features of sexually dimorphic species (that is, species in which males and females have different physical features) that are particularly attractive to the opposite sex. These features seem to have evolved solely for their role in mate selection and have no other benefit to their possessors. Indeed, when such traits in a species are too conspicuousăsuch as bright colors or long tailsăthey may be a handicap in other tasks, such as avoiding predators. [Image] Humans are sexually dimorphic. Each sex has traits that the other sex finds particularly attractive and uses, at least in part, as cues for mate selection. The question of exactly what those traits are has long been of interest to evolutionary psychologistsăscientists who have applied Darwin's concept of natural selection to human behavior. At Newcastle University, M. J. TovČe, D. S. Maisey, J. L. Emergy, and P. L. Cornelissen recently identified what they believe to be a species-typical characteristic of human females that males find particularly attractive and may use in mate selection: body mass index, or BMI. Their research rests on the assumption that women's bodies provide two important cues: shape and weight. Some studies have shown that waist-to-hip ratio (WHR) is important. The lower the WHR, the more curvaceous the body, which correlates with optimal fat distribution for high fertility. In earlier studies using line drawings, men ranked women having a low WHR attractive. TovČe's research team thought line drawings may be too divorced from the appearance of real women to provide a good index of attractiveness, so they used scanned photographs of women. The women all wore tight gray leotards, posed similarly, and had their faces digitally obscured to remove facial cues. The images represented a range of WHRs between 0.68 and 0.98. (Earlier studies suggest that the optimal WHR for attractiveness is 0.7.) Other researchers have found that changes in body mass index (BMI), a ratio of weight scaled for height, have a strong impact on a woman's health and reproductive potential. Based on this and their own research, the team decided to vary the stimuli along that dimension. The range of BMIs used in this study was from 10 to 37, where 10-14 is considered emaciated, 15-19 is underweight, 20-24 is normal weight, 25-30 is overweight, and 31-37 is obese. Undergraduate men were asked to rank the digitized images, presented one at a time, using a scale ranging from 0 (least attractive) to 9 (most attractive). They were first allowed to view all stimuli without ranking them, just to give them an idea of the range of variability. Then, on the second viewing, they ranked the stimuli. The results were intriguing. With these more realistic stimuli, the most important index of attractiveness was BMI, not WHR. The men's ratings were highly correlated with variations in BMI, but not correlated with variations in WHR. Specifically, BMIs judged the most attractive were in the range of 18-19. BMIs below or above that range had significantly lower attractiveness ratings. In fact, the farther the BMIs were from the 18-19 optimal range (either up or down), the more the attractiveness ratings decreased. Although BMIs of 18-19 fall just below the normal range of 20-24, other research has indicated that the 18-19 range represents the optimal BMI for health and fertility. Thus males were showing a preference for women who have the greatest potential for reproductive success, which is the hallmark of evolutionary theory. BMI is probably not the only visual cue men use. Other cues, such as the degree of symmetry of facial features, are also important in attractiveness ratings, and these cues were intentionally not made available to the subjects in this study. Mate selection, of course is a two-way streetămating is not solely the result of males selecting females. Just as in most nonhuman species, a female may be courted by a number of males, and it is the female who ultimately decides with whom she will mate. So, while BMI serves as a cue for males in courtship, human females may also use species-typical cues in mate selection. What they are, however, is the subject of future research. Resources 1. TovČe M. J., Maisey D. S., Emery J. L., and Cornelissen P. L. (1999). Visual cues to female physical attractiveness. Proceedings of the Royal Society of London B (266): 211-218. The original paper. 2. TovČe M. J., Maisey D. S., Emery J. L., and Cornelissen P. L. (1999). Visual cues to female physical attractiveness. The online version of the original article available for subscribers to Proceedings of the Royal Society of London B. (3 April 1999) 3. BMI Calculator. Health Check Systems. An online interactive means of calculating your body mass index (BMI). (3 April 1999) [Copyright 1999, Peregrine Publishers, Inc. All Rights Reserved.]