CIA agents in Havana complaining of mental fog, dizziness and ear pain in 2016. Children in Miami in 1974, hyperventilating and wracked with abdominal pain. A medieval outbreak of the “dancing plague”. A chorus of meowing nuns.

These mysterious and seemingly disparate events may have a simple explanation — and one that’s often overlooked when it comes to understanding strange new syndromes.

For a full list of sources used in this episode visit Tim Harford.com.