Why Are Humans Ticklish? Hint: Scientists Still Can’t Agree On An Answer

Scientists still don’t know why humans are ticklish, despite centuries of curiosity from Socrates, Aristotle, and Darwin.

Ticklishness has two forms: light-touch sensitivity (knismesis) and laughter-inducing tickling (gargalesis).

New rat studies link the laughter-like response to play, social context, anxiety, and activity in brain regions such as the somatosensory cortex and periaqueductal gray.

The work suggests tickling may shed light on social touch, emotion, self-awareness, and survival-related brain responses, but the human explanation remains unresolved.