for National Geographic News
When considering a mate, people's assessment of physical beauty is mostly about symmetry, scientists say.
A new study finds that the more symmetrical a person's body is, the more appealing that person is to the opposite sex.
Previous research had shown that balanced facial features are considered more beautiful by observers, partially confirming notions put forth by the ancient Greeks that symmetry is an important ingredient in human judgments of beauty.
The new finding suggests that the same is true for body symmetry, and that symmetrical proportions could be signs of biological fitness.
"In animals with two sides that were designed by natural selection to be symmetrical, subtle departures from symmetry may reflect poor development or exposure to environmental or genetic stress," said study team member William Brown of Brunel University in the U.K.
"In many species these departures are related to poor health, lower survival, and fewer offspring."
The research is detailed in this week's issue of the journal Proceedings of the National Academy of Sciences.
Using a 3-D optical scanner similar to ones used in the medical and fashion industries, Brown and colleagues created detailed virtual models of the bodies of 77 adult human subjects and measured the models for degree of symmetry.
The researchers then asked a separate group of 87 volunteers to rate the attractiveness of bodies of the opposite sex based solely on visual appeal.
To remove any potential bias due to facial features or skin color, the heads of the virtual models were removed and the bodies were all tinted the same neutral shade.
Although differences in left-right symmetry are usually almost undetectable to the naked eye, both men and women reported symmetrical bodies to be more attractive.
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