SEATTLE - It might seem elementary that if he's hot on the dance floor, he's more desirable as a mate. Now there's a scientific explanation: body symmetry.
University of Washington
The animated figures captured the movement but not the shape or features of the dancers.
A new study by Rutgers University anthropologists shows that body symmetry, a key to good dancing, is associated with attractiveness.
"At least since Darwin, scientists have suspected that dance so often plays a role in courtship because dance quality tracks with mate quality," said Lee Cronk, associate professor of anthropology. "But this has been hard to study because of the difficulty of isolating dance movements from variables, such as attractiveness, clothing and body features. By using motion-capture technology commonly employed in medical and sports science to isolate dance movements, we can confidently peg dancing ability to desirability."
University of Washington computer scientists duplicated the movements of 183 Jamaican teenagers dancing to popular music in animated figures. The researchers then asked peers of the dancers to evaluate the dancing ability of the figures. To get the most objective results, the figures were gender-neutral, faceless and the same size.
The judges "were evaluating dance quality rather than sexiness and dancers," Cronk said. "Symmetry is an indicator of mate quality."
The young Jamaicans were selected because they had been involved in another study by Rutgers but Cronk said: "We were afraid if we did it in the U.S., we would end up with people biased, less natural; we wanted a full range of dancers from experienced to those not as comfortable."
The study shows a strong relation between dance and courtship "because dance shows off some aspects of mate quality better than other forms of interaction," Cronk said.
Researchers were surprised to learn that the effect was stronger for women watching men dance rather than men watching women, and that men received higher ratings. The theory behind that is that women invest more in offspring and are in a position to be the choosy ones, Cronk said.
This is especially true in a society where there is more economic equality, and where desirability is not based on power and wealth. Also, contrary to what many believe, women do care a lot about looks.
"There has been floated the idea that women care less about looks, but recent research shows women do care a lot, especially if there is economic equality," Cronk said. "So we predict an accentuated choosiness among females."
This all emerges from Darwin's sexual selection theory -- that individuals choose mates on the basis of some measure of physical attractiveness, he added.
"In species where fathers invest less than mothers in their offspring, females tend to be more selective in mate choice and males therefore invest more in courtship display," said fellow researcher William Brown. "Our results with human subjects correlate with that expectation. More symmetrical men put on a better show, and women notice."
Cronk said the researchers will follow group as they grow up and might do a similar study in a society where men are more empowered and see if they're choosier about the dance quality.
University of Washington computer scientists captured the moves by affixing infrared reflectors on 41 body locations of each dancer, from head-to-toe and arm-to-arm, to capture and measure detailed body movements. They fed data into programs that first created dancing animations of stick figures and then converted those animations into virtual human forms.
The technology is a first for this type of study. It's normally used in medicine or special effects in film.
"This is a new way to use the equipment…and we captured certain ways in how they dance and interact and learn how movement is relevant in social everyday life, from regular interaction to sexual selection," said Zoran Popovic at the UW. "This will open a new avenue in research in human movement and dance."