An equation for attraction
People rate shapeliness based on a girl's ratio of volume to height.Some people say it's long legs that count, others say it's the bits on top.
But according to a Hong Kong study, the best way to judge a woman's attractiveness is to take her volume in cubic metres and divide it by the square of her height. The researchers call the figure her volume-height index, or VHI.
The researchers showed more than 50 people 3D movies of rotating female silhouettes in assorted shapes and sizes. They asked the viewers to rate their attractiveness on a scale of 1 to 9. VHI was the formula of the women's body measurements that best matched the scores, they found1.
The idea is really just a slight modification to an older, easier-to-calculate measurement: the body mass index (BMI), defined as weight in kilograms divided by the square of height in metres.
Although more commonly used to describe health rather than attractiveness, previous investigations by Piers Cornelissen at Newcastle University, UK, have shown that women with a BMI of 18 to 19, for example, are ranked as the most lovely. That's at the slim end of the normal BMI range, 18.5 to 24.9.
Jintu Fan and his team at Hong Kong Polytechnic University in Kowloon, who came up with the VHI index, decline to mention the 'ideal' number.
Mental maths
If VHI were used alone to rate attractiveness, a woman with a straight tube of a body could come out as well as a curvaceous one.
The Hong Kong researchers think that people size up other body proportions when they rate attractiveness. They gauge how long a woman's legs are relative to her total tallness, or assess waist-to-hip ratios.
But this doesn't mean that those with a roving eye are churning through tortuous sums in their heads to assess attractiveness. People probably make an instinctive assessment of shape that tallies with more accurate measures of size, says Cornelissen.
A winning VHI or BMI may simply reflect people's evolutionary preference for women who are healthy or fertile, explains Cornelissen. Alternatively, our culture's emphasis on youth and health may programme us to see a leaner body as appealing.
© Nature News Service / Macmillan Magazines Ltd 2004