What makes the human body attractive?

A study by Dr William Brown and colleagues in Brunel University's School of Social Sciences and School of Engineering and Design, published this week in the Proceedings of the National Academy of Sciences (PNAS), has revealed an explanation for the correlation between attractiveness and bodily characteristics like height, breast size, long legs, broad shoulders or a curvy figure.

The study also explored the degree of asymmetries between the left and right sides of the body, which is widely believed to be an indirect measure of developmental quality in many species including humans.

Using Brunel's high-tech 3D optical body scanner to accurately measure human body proportions, the study was the first of its kind. Co-author, Dr Jinsheng Kang from Brunel's School of Engineering and Design, explains the methodological benefits of this new technology: "The 3D body scanner accurately extracts hundreds of measurements of the human body, including volume, in six seconds and removes a potential source of measurement error, the human experimenter."

Through their research at Brunel's Centre for Cognition and Neuroimaging, Dr Brown and a team of scientists identified a property dubbed 'body masculinity', a mathematical fusion of traits including greater height, wider shoulders, smaller breasts and shorter legs.

Key findings of the study included:

• When asked to assess the attractiveness of female 3D body images, men rated those with less body masculinity most attractive, and vice versa
• High masculinity correlated with fewer departures from perfect bodily symmetry in males but with more asymmetry in females, suggesting that those with good development and health may have bodies that exaggerate sex-typical bodily features.

Commenting on the research, Dr Brown explains: "It is widely believed that human beings are attracted to one another as a result of genotypic and phenotypic quality - in other words, their prospect as a mate who will yield higher quality offspring for the chooser."

"My previous research suggested that bodily symmetry is not necessarily what people attend to when they find someone attractive but nonetheless the physical cues that they do prefer may reveal an individual's underlying developmental quality (i.e. degree of symmetry). This new research identifies an explanation for the correlation between bodily shape and attractiveness: your body proportions, shape and stature are signals that conspicuously advertise your good development or health and therefore the degree to which you are a desirable reproductive partner. In many species fewer departures from perfect symmetry are associated with good development, health and reproductive success."

He concludes: "It seems that because bodily asymmetries are too subtle to be seen with the naked eye, evolution has instead engineered more conspicuous signals and displays, such as broad shoulders, curvy waist lines or smooth dance moves to indicate mate quality."