Tickling makes great apes crackle with laughter, according to a study from the University of Portsmouth (UK) published in the journal Current Biology . Indeed, like human children, younger chimpanzees, bonobos, orangutans, and gorillas squeal and yell when tickled. And although the sound that these primates produce when they exhale is different from the human "ha-ha", scientists have just shown that it can be defined as laughter.
To reach this conclusion, Marina Davila Ross and her colleagues analyzed sound recordings of vocalizations caused by tickling in babies and young orangutans, chimpanzees, gorillas and bonobos, as well as in humans. Subsequently, a phylogenetic analysis of the acoustic data showed that the expressions caused by tickling in the five species have their origin in a common ancestor of more than 10 million years ago . The data also suggest that, although the origin of laughter is shared, when the evolution of humans separated from that of primates, human laughter also evolved, exaggerating its acoustic features.
