As you're developing, all sorts of things come at you, like diseases and injury. If you're able to develop symmetry despite all of that, then that would indicate to others that you have what it takes to make a go of it in that environment.
At least since Darwin, scientists have suspected that dance so often plays a role in courtship because dance quality tracks with mate quality. By using motion-capture technology ... we can confidently peg dancing ability to desirability.
With motion capture, we can do that and get just pure dance movements.
