iStock

Dance like no one is watching—or so they say. But people often are watching. Truth be told, they’re judging your moves. A study published last week in Scientific Reports used video of a variety of dancing women to pinpoint how observers distinguish good dancers from bad. If you care about such things, there’s one big takeaway: Swing those hips. And if you guessed all this has something to do with sex, you guessed right.

The researchers, from the laboratory of psychologist Nick Neave at the University of Northumbria in the United Kingdom, filmed 39 women between the ages of 18 and 30 dancing for 30 seconds to a basic drum rhythm. They used a stop motion camera, which allowed the team to break down and analyze specific patterns of movement. Video clips were converted into 3-D avatars so that the appearance of all the dancers was the same. Then observers (57 men and 143 women) rated each dancer on a scale from “extremely bad” to “extremely good.” (See links to video clip below.) Finally, the ratings were evaluated against measurements of the women’s movement patterns.

S1_BadDancer_Example

S1_GoodDancer_Example

Three types of movement most impressed the judges: wider hip swings, more asymmetric movements of the thighs, and a certain amount of asymmetry in the arm movements as well. Too much asymmetry though and a dancer risked verging into “uncontrolled pathological movement,” which is never a good idea on the dance floor or anywhere else probably.

Why hip swings? Fertility, of course. The hips are regarded as abundantly female. According to Neave and his colleagues, previous research has shown that women’s dance is rated more attractive during times of high-fertility, and lap dancers get bigger tips when they’re ovulating. As for the appeal of asymmetrical movements, the researchers suggest that may have something to do signaling “well-developed motor control.”

What about men?

Lest you think it’s not fair to focus only on women’s attractiveness, Neave’s team reported on men first, in a 2011 paper they called, “Male dance moves that catch a woman’s eye.” (You don’t see titles like that every day in the science literature.) The key moves for men were larger and more varied movements of the neck and trunk, and faster movements in the right knee (a finding that probably reflects that 80 percent of the population is right-footed). The results suggested to the researchers that the finest male dance moves serve as “honest signals of male quality in terms of health, vigor or strength.” No wonder we speak of those who can’t dance as having “two left feet.”

Studies like these are fun, but they also tell us something significant about the social signals we are sending and receiving at any point in time, often without quite realizing how much we are saying, so to speak. From an evolutionary point of view, dancing is a courtship display. The way we dance conveys a lot of information to potential partners. Anyone looking for a mate might be wise to do some practicing in front of the mirror before you hit the dance floor.