There’s a chance that if you visited southern Italy during the Middle Ages, you might happen upon a port town where people were dancing uncontrollably in the streets. You’d find them frantically spinning, jumping…even crawling on the ground. But unlike the broader “ dancing mania ” that was taking place across Europe at the same time, this dance, dubbed the “tarantella,” was more than a sickness. It was also a cure.

“Some people say that the bite of a spider caused people to tremor and shake,” Anna Harsh , a professional dancer and founder of the Allegro Dance Company , which specializes in Italian folk dances, tells Popular Science .…