Have you ever tried to tickle an orangutan? No? Damage. Fortunately, researchers have done it for you. And the results are fascinating: great apes laugh like us, and not just a little. A discovery which allows us to better understand the evolution of human language.
The study included four orangutans, three bonobos, two gorillas and four chimpanzees. By analyzing their tickle-induced laughter, researchers discovered that all great apes laugh with a regular rhythm: their vocalizations are evenly spaced, like metronome beats, reports IFL Science. A characteristic found in human laughter.
Universal laughter
This common trait probably already existed in our common ancestor who lived around 15 million years ago. “Before conducting this study, I thought there would be more irregularity in the laughter of our more distant cousinsconfides researcher Chiara De Gregorio. Instead, the regularity of laughter rhythm appears remarkably conserved across all great apes. This suggests that we have been laughing this way for around 15 million years.”
If the starting point is the same, humans have developed a capacity that other great apes do not possess: adapting our laughter to the social context. We laugh more quickly when we are tickled than during a game, for example. Chimpanzees, bonobos, orangutans and gorillas maintain approximately the same laughter whatever the situation.
“In great apes, laughter appears to have begun as a stereotypical rhythmic signal, used primarily in a limited number of social contexts such as play or tickling.explains De Gregorio. In humans, on the other hand, laughter has become extraordinarily varied. We can produce a polite, discreet little laugh as well as an uncontrollable burst of laughter, or even an ironic or “forced” laugh to signal something other than genuine amusement.” This flexibility could indicate our ability to control our intonations: a mastery that was fundamental to the emergence of speech and language.
“Laughter is not language, of course, but both rely on the ability to control and modulate the sounds produced”underlines De Gregorio. The researchers also noted that this modulation capacity exists in the form of a continuum: it is all the more developed the closer the species is to human beings. This suggests that the control of vocalizations has been gradually established since we started laughing millions of years ago.
This discovery opens an unexpected window on our extinct cousins, the Neanderthals. “Our results suggest that they probably produced rhythmically regular laughter.says De Gregorio. Their laughter would probably be more variable than that of apes but less than that of humans. In other words: the Neanderthals laughed, just a little less well than us.
