Rats Laugh When You Tickle Them, But You Cant Hear It

In the late 1990s, neuroscientist Jaak Panksepp made one of the more delightful discoveries in animal behavior research: rats laugh. Not in a way you would recognize at first — their giggles happen at ultrasonic frequencies around 50 kHz, well above the range of human hearing. But to the rats, it is very much a laugh, and they enjoy it immensely.

Panksepp and his team confirmed this by tickling rats the same rough-and-tumble way young rats play with each other. The tickled rats produced far more ultrasonic chirps than rats that were simply touched normally — and they actively sought out the tickling hand afterward, scurrying back for another round. The most-tickled rats also tended to be the most upbeat in their daily rat activities.

Later research found that tickled rats release dopamine — the brain's reward chemical — during the sessions. Even anticipating a tickle session triggered measurable responses in their brains. And just like humans, rats have ticklish hot spots: the belly is especially effective, which honestly tracks.

So the next time someone insists that laughter is a uniquely human thing, you can gently point out that a rat has probably been giggling at frequencies you cannot hear while you were busy being serious about something. This information should bring you either great comfort or mild existential amusement, ideally both.