The Dancing Plague of the Middle Ages
For centuries, crowds of people danced to death

In 1237, something eerie happened in the German town of Erfurt. A large group of children spontaneously started dancing and, in a state of trance, jumped and danced their way to Arnstadt, a city 20km (12 miles) away.
Around the same time, a legend was born in the far-away town Hamelin. It was…