Why do we laugh when tickled?

Tickling that produces laughter, known as gargalesis, targets sensitive areas such as the ribs, underarms, and feet, and the laughter it triggers is largely a reflex rather than genuine amusement. Brain-imaging studies show tickling activates not only the region that processes touch but also the hypothalamus, which governs the fight-or-flight response, hinting that the body reacts partly as if to a threat on vulnerable spots. Crucially, you cannot tickle yourself because the cerebellum predicts the sensation of your own movements and cancels it out; the surprise is essential, which is why tickling requires another person. Scientists think ticklishness evolved as a social and defensive mechanism: it strengthens bonds between parents and children through play and teaches us to protect vulnerable parts of the body. Even so, being tickled too much can become genuinely unpleasant despite the laughter.