The one thing you probably think you understand about how cats communicate — purring means they’re happy! — isn’t exactly right. Cats do indeed purr when they’re happy, but that’s not the most accurate translation of the sound’s meaning, Cromwell-Davis explained. “You can have cats that are happy and content purring, but also a cat that’s injured or sick will purr,” she said.

Instead, purring means something more like, don’t go anywhere, please. It’s more likely a solicitation for care, in other words, than purely an expression of contentedness. “They haven’t got a good way of asking for help — it’s not in their language — so they do the next best thing, they do the purring thing,” said John Bradshaw, a University of Bristol anthrozoologist and the author of Cat Sense: How the New Feline Science Can Make You a Better Friend to Your Pet. “The meaning is not exactly right, but it’s the closest they can get to it.”