Dr [Nick] Neave [of Northumbria University] asked young men who were not professional dancers, to dance in a laboratory to a very basic drum rhythm and their movements with 12 cameras.
These movements were then converted into a computer-generated cartoon - an avatar - which women rated on a scale of one to seven. He was surprised by the results.
"We thought that people's arms and legs would be really important. The kind of expressive gestures the hands [make], for example. But in fact this was not the case," he said.
"We found that (women paid more attention to) the core body region: the torso, the neck, the head. It was not just the speed of the movements, it was also the variability of the movement. So someone who is twisting, bending, moving, nodding."
Movements that went down terribly were twitchy and repetitive - so called "Dad dancing".
In the video at that link, Dr. Neave adds:
"The head and the neck and the torso can move around three different angles - forwards and backwards, side to side, turn around - and somebody who's putting all those moves together, in a different way, and making them sometimes big and sometimes small, and showing variability, and flexibility, and creativity in the way that they move their head and their neck and their body, they will be percieved as a good dancer. A bad dancer is someone who engages in very rigid, stereotypical movements. A head nod - a headbanger, for example, is a bad dancer."Makes sense to me, huh. In so many ways.
I know that science reporting is often pretty dodgy. But in in this case they do tell us what journal the article is in, the Royal Society Biology Letters, which allows me to check the abstract and say that the news article doesn't go much beyond the abstract itself, which (in part) says this:
Linear regression subsequently revealed that three movement measures were key predictors of dance quality; these were variability and amplitude of movements of the neck and trunk, and speed of movements of the right knee. In summary, we have identified specific movements within men's dance that influence women's perceptions of dancing ability. We suggest that such movements may form honest signals of male quality in terms of health, vigour or strength, though this remains to be confirmed.
Indeed, it's possible that moving the core body region in a controlled, varied, creative and twisty way is just genuinely quite difficult, which I think is what they're saying with the technical sense of "honest", and certainly doesn't contradict my personal experience (hello, confirmation bias).
In fact I have several questions about this, such as how the subjects rated their own dancing, how other males rated the dancing, whether there was any definition of dancing, and whether the researchers went beyond the distinction between 'professional' and otherwise. Part of the abstract I didn't quote also implies that the dance of men was found to be more informative than the dance of women, and it would be interesting to know if that was true, or if they didn't measure any female subjects for some reason, or if there just wasn't enough difference between female subjects they measured to be able to tell. I also wonder what the overall goal of the study was and whether it's part of a wider programme of research. The article will be available for free in a year's time; at the moment it costs a rather eye-popping £27, which I don't think I can justify.
And also, why the right knee? Did it matter if they were left-handed? In fact, can you tell from someone's dancing if he's left-handed or not? I know you can with at least some beginner tangueros, who (I remember noticing) if not given definite instruction or obstruction sometimes start with a motion to the right instead of the stereotypical leftward weight-change.
A little bit more digging finds two videos from the study.
There's a lot more in the Letters about animal locomotion, although I don't think any of it changes the lots-of-data-and-no-theory situation.