Rats Laugh When Tickled — You Just Can't Hear It

In the late 1990s, a neuroscientist named Jaak Panksepp made a strange discovery. When he tickled rats, they chirped — rapidly, repeatedly, at a frequency far too high for the human ear to detect. He could only hear it using special equipment. And when he looked at what the rats were doing alongside those sounds, the conclusion was difficult to avoid: they were having a wonderful time.

Rats communicate at multiple frequencies, but their laughter — if that is the right word — occurs at around 50 kilohertz, roughly two and a half times higher than the upper limit of human hearing. For most of history, nobody noticed these sounds because nobody was listening in that range. Panksepp's team began recording them and found that the 50kHz chirps appeared consistently during play — when rats chased each other, when they were tickled, and when they anticipated something enjoyable. The sounds were not random noise. They were expressions of something.

The more striking finding was what the rats did after a tickling session. Given a choice between moving toward or away from the researcher's hand, the rats consistently moved toward it. They were not simply tolerating the contact — they were actively seeking more of it. Young rats showed the strongest response; as rats age, their enthusiasm for tickling tends to decrease, much as human children find tickling funnier than adults do. The parallel was difficult to dismiss.

Panksepp's research sparked a wider conversation about emotion in non-human animals. For a long time, scientists were reluctant to describe animal behaviour in emotional terms — it was considered unscientific, too prone to anthropomorphism. But the consistency and predictability of the rat chirps suggested something genuine was happening. The rats were not merely reacting. They appeared to be experiencing something — and expressing it. Whether that experience is truly comparable to human joy remains an open question. But the chirps exist. The behaviour is real. And the rats keep running back toward the hand.

The next time you see a rat and assume a simple, instinct-driven creature, remember Jaak Panksepp and his recording equipment. Somewhere in that small, fast-moving animal, there may be laughter you simply cannot hear.