Around the world in 5 points: The universal tickle map is revealed
A large-scale international study found that areas of sensitivity to tickling on the human body are identical across different cultures, shattering centuries-old theories. An artificial intelligence model predicted the most ticklish areas with an accuracy of nearly 100%. Researchers: "This is not just a reaction to touch, but an evolutionary mechanism for strengthening social bonds."
Tickling is not just an amusing child's game, but a universal evolutionary trait with a fixed and precise "body map" — this is the conclusion of a new study published in the scientific journal Nature Human Behaviour. The researchers found that the areas of the body most sensitive to tickling are surprisingly identical among humans from different cultures, a finding suggesting that this unique sensation is likely intended to strengthen social bonds and closeness.
The central discovery of the study relies on an advanced artificial intelligence model. After the model was "trained" on data from only one culture, it managed to predict with an accuracy of nearly 100% the areas sensitive to tickling among participants from different cultures. The findings, collected from about 450 adults from China, the Netherlands, and Greece, consistently showed that the main "tickle centers" on the human body are the neck, armpits, abdomen, sides of the body, and the soles of the feet.
Darwin was right, Aristotle was wrong
These findings support the theory proposed by Charles Darwin, according to which sensitivity to tickling is stronger precisely in areas that are not exposed to frequent daily touch. Surprisingly, areas with high nerve density that receive constant contact — such as the palms and lips — were ranked among the least ticklish places on the body. In doing so, the new study contradicts ancient historical theories, for example, that of Aristotle, who claimed that thin skin is the main factor for tickling, and refutes the belief that the trait originally evolved to protect vital organs.
The researchers who conducted the study are Ziliang Xiong and Konstantina Kilteni from Radboud University in the Netherlands. In answering the question of why we actually tickle, the researchers explain that it is a deep social behavior intended to create and strengthen bonds between humans. Laughter — the most common reaction to tickling — does not always indicate pure pleasure, but it serves as a reliable social signal that is almost impossible to fake. Touch directed at vulnerable areas temporarily disrupts a person's voluntary control, thereby providing immediate feedback that increases trust and closeness.
Ancient neural mechanism
"Ticklishness is a category in itself, physiological and psychological," declared study author Xiong, "and it is not just a byproduct of other body sensations."
The researchers define the phenomenon as a distinct sensation produced by the nervous system, and located at a unique junction between touch, emotion, and social interaction. The broad social context is also prominent in the data: about 98.4% of the participants in the study reported that they had been tickled in the past, and 95.8% admitted that they had tickled others.
The evolutionary explanation receives significant reinforcement from the animal world as well, with evidence of similar reactions to tickling among apes, rats, and even meerkats — something that points to an ancient source common to many mammals. The researchers emphasize that their study focused on the type of tickling that induces laughter (known as "gargalesis"), as opposed to light and very gentle touch (known as "knismesis"), which is more similar to the sensation of a fleeting itch.
