Q. Why can some people wiggle their ears, but not others?

A. People cannot swivel their ears to point at a sound source, while many animals, like cats and dogs, can do so with ease. Humans do have weak vestigial muscles attached to the shell of the ear, called the auricle or pinna, as well as evidence of a vestigial nervous system, which could have functioned to orient the ears.

Some people can control their auricular muscles to move the ear slightly but to a noticeable extent, an ability that seems to have a genetic basis.

A 2015 study in the journal Psychophysiology reviewed past research on the auricular nerves and found indications that the system could have been adapted to respond to sounds. For example, shifting the eyes from side to side produces weak electrical activity in ear muscles and a minuscule curling of the outer edge of the ear, and a sudden noise behind one ear elicits weak electrical activity in the muscles behind that ear.

As for the familial nature of wiggling, the inheritance pattern is unclear and does not appear to have a simple dominant-gene mechanism.