Tickling is one of the strangest things the human body does. A few light touches can trigger laughter, squirming, and an overwhelming urge to escape, even though nothing is actually causing harm.

Researchers think ticklishness may be linked to the body's sensitivity around vulnerable areas such as the neck, ribs, armpits, and feet. Exactly why humans evolved this response remains uncertain.

The really surprising part is that most people cannot tickle themselves.

Whenever you move, your nervous system predicts what that movement should feel like. If the sensation matches the prediction, the response is dialed down. Because your body knows exactly where and when your fingers will touch, the sensation loses much of its impact.

Someone else's touch is different. It is harder to predict, so the response remains strong. That unexpected contact can trigger the familiar combination of laughter, wriggling, and an urgent desire for the tickling to stop.

In other words, ticklishness is not just about being touched. It is also about being surprised.