Researchers from Northumbria University in England asked 39 women between the ages of 18–30 to dance to the beat of a drum while a motion-capture system recorded their movements sans any physical features (think stickman-style).
They then asked 57 men and 143 women to view the footage and rate the dancers on a scale of 1–7. After analyzing the ratings, two researchers trained in the bio-mechanical analysis of human movement were able to study the five most popular and five least popular, pinpointing the joint angles that defined them as either good or bad at dancing.
Their conclusions prove Shakira was on the money; judges of both genders appreciated mobile hips with plenty of swing. They also deemed asymmetric thigh movements—and, to a lesser degree, arm movements—more attractive. In other words, limbs that can move in opposition to one another, exemplified by the choreography in Run the World (Girls).
There’s an evolutionary explanation for why this is attractive. Dance has historically been used as a mating ritual, and hip-focused movements are traditionally an expression of femininity and (by extension) perceived fertility.
The appeal of asymmetric movements is that they’re tricky to perform—like rubbing your tummy and patting your head—and therefore indicate better motor control.
A 2006 study published in the Public Library of Science’s genetics journal suggested that, as dance was an ancient form of communication for our ancestors, people with a sense of rhythm have a social advantage. Their research found that dancers’ DNA contained genes associated with being adept communicators—genes the non-dancers didn’t have—which gave them the evolutionary upper hand.