This article is taken from the monthly journal Sciences et Avenir – La Recherche #905-906 July-August 2022.
It was ticklish at first… This is the oldest way to induce laughter, an archaic behavior that “goes back at least to the last common ancestor of great apes and humans, 10 to 16 million years ago,” according to British psychologist Marina Davila Ross. Ticklish orangutans, gorillas, bonobos, and chimpanzees do produce “vocalizations with acoustic signatures very similar to ours.”
While the laughter likely arose from labored, ragged breathing, tickling itself is an extension or variation of the courtship, hugging, fighting, playing, or sexual foreplay inherent in the group life of social species, Robert says. According to this American neuropsychologist, laughter, “unlike crying, is not innate in humans and appears only in infants at the age of 4 months.” This suggests that sobbing predates fun in evolution, probably because the former function as a vital signal of warning, fear, hunger. Laughing in response to a tickle will send a message like “everything is fine, my basic needs have been met, now is a good time to socialize, play, explore”, establishing communication between two people beyond language and promoting mutual learning.