Bad dancers make repetitive moves that are restricted to their arms and legs Northumbria University

The enduring mystery of why men rarely flatter themselves when they take to the dancefloor may finally have been solved.

A team of psychologists used video footage of men strutting their stuff to pinpoint the killer moves that separate good dancers from bad.

Men who were judged to be good dancers had a varied repertoire and more moves that involved tilting and twisting the torso and neck.

But the majority of men displayed highly repetitive moves that used their arms and legs, but not the rest of their bodies.

"It's rare that someone is described as a good dancer if they are flinging their arms about but not much else," said Nick Neave, a psychologist at the University of Northumbria, who led the study.

"Think about a head banger. Their head movement has a large amplitude, but it's not changing direction or showing any kind of variability. That's a bad dancer. Or someone who is just twisting and turning left and right? That's a bad dancer too."

While features such as body shape and facial symmetry are well known indicators of healthy development, a person's dance moves may send out more subtle clues about their potential as a mate, Neave said.

Neave's team recruited 19 male volunteers aged between 18 and 35 and asked them to dance to a simple drum beat in front of a video camera for 30 seconds. To capture the dance moves, 38 infra-red reflectors were attached to their clothing. These produce bright spots that allow the movement of every limb and joint to be tracked and studied in detail.

The researchers used software to transfer each man's dance routine to an avatar on a computer screen. This ensured that the judges ranked the dancers according to their moves and not their height, looks or other physical features.

The dancers were judged by 37 straight women, also aged 18 to 35, who watched the avatar perform 15 seconds of each man's routine before ranking them on a scale of one to seven, where one was very bad dancing.

"The head, neck and upper body come out as the key features that are important for good dancing and that surprised us," said Neave, whose study is published in the journal Biology Letters. "When you see brilliant dancers, you'll see their bodies, heads and necks are all doing ever so slightly different things in time to the music."

Will Brown, a psychologist at the University of East London, said more work was needed to disentangle why dancing is attractive and its biological significance.

"When you have so much movement data from a relatively small sample of dancers, you might get chance associations between certain moves and dance attractiveness," he said.

"Flexing the trunk while dancing may be attractive, but we need to show it is indicative of a better quality male using an independent measure of biological quality."

Neave said his group is working through the results of blood tests on the men, which appear to show that the better dancers are healthier.