In July 1518, a woman in Strasbourg known as Frau Troffea began dancing in the street, seemingly unable to stop until she collapsed of exhaustion. Soon, more people were struck by this strange urge to dance. By August, some 400 people had been affected—and as a result, a few died of heart attacks and strokes, according to History.
Weirder still, there was no clear cause or explanation for the condition. John Waller, a historian who wrote The Dancing Plague, believes the phenomena might have been a result of the fact that the people of the time believed in a saint who had the power to make people dance. That belief, combined with the rampant disease and famine of the time, could have driven believers to dance to their graves.
