Why humans and great apes giggle alike when tickled

Chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla) and children laugh in similar rhythms when tickled. Researchers found that kids and apes left evenly spaced intervals between laughing sounds during a tickle attack, though children had a faster laughter rhythm compared with apes. Laughter might have picked up pace during the course of human evolution, the team suggests, which could reveal “something about laughter itself, but also, in a way, about the evolution of human speech”, says primatologist and study co-author Chiara De Gregorio.