Why do we laugh when we get tickled?

When someone touches a sensitive spot on our body, our brain gets a sudden surprise. If we trust the person touching us, that surprise turns into laughter. The part of our brain that handles feelings and danger deals with tickling in a mixed-up way, like it is both danger and a game. That is why we want to get away and laugh at the same time.

Here is something interesting: we cannot tickle ourselves! Our brain already knows about our own touch, so there is no surprise. Tickling only works when someone else does it, because then our brain cannot guess what is about to happen.

Scientists think tickling is a kind of social game. Animals get tickled too! Monkeys, and even mice, make their own kind of laughing sound when they are tickled. This shows that laughing might be a very old behaviour linked to friendship and play.