Have you ever seen someone wiggle one ear? How about both at the same time? How do they do that?

Ear movement is common in many mammals, including cats, dogs and horses, and usually serves to swivel the ear towards the direction of a sound. A group of muscles called the auriculares are responsible for this movement. This group includes: the auricularis anterior, which draws the ear up and forward; the auricularis superior, which raises it; and the auricularis posterior, which pulls it backwards.

In humans, ear wiggling is a vestigial feature, which means it is a trait that was useful in ancestral creatures but that eventually became functionless. There aren’t any studies that say for sure how common ear wiggling is in humans, but anecdotal reports suggest that around 10 to 20 of the population are ear wigglers.

Other reports suggest that ear wiggling is teachable, and that people who are able to raise one eyebrow or otherwise carefully control their facial muscles are most apt at learning how to do it.

But, some people can’t stop wiggling their ears. Moving ear syndrome is a type of dyskinesia, in which voluntary muscle movements diminish or involuntary movements, including tics and spasms, occur. In some cases, the muscles involved in moving ear syndrome are paralyzed with injections of botulinum toxin, the same type of bacteria that is used in Botox.

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