Human ticklishness is a widespread, culturally shared and bodily organized sensory experience

Human ticklishness is one of the oldest yet unresolved scientific puzzles. As early as the time of Aristotle and Socrates, scholars have speculated on its origins and function, but fundamental questions remain. Is ticklishness culturally shared or specific? Does it follow a structured bodily topography, and how does it relate to other bodily sensations? Here we analysed data from three cultural groups (Chinese, Dutch and Greek) and reveal consistent behavioural patterns and social dynamics. We extracted a high-resolution bodily map of ticklishness and show that it generalizes across cultures and individuals, and is distinct from maps of touch sensitivity, pain and pleasure. When tested against predictions from five historical and contemporary theories, we show that no single theory can fully explain the ticklishness topography. Although ticklishness is stronger in rarely touched regions, supporting Darwin's hypothesis, its topography relies on a psychophysiological mechanism that is more complex than previously assumed.