"Huh-ha-huh!" Instead of "ha ha ha!". As the great primates, human babies laugh basically inspiring the air, before evolving towards an adult laugh, more communicative, expanding the air, according to a study.
The idea of comparing the man and the animal in the matter of laughter emerged during a conference of a primatologist in Sicily, who attended a young researcher and a friend of his.
That teacher showed how the mechanism of laughter worked among the great primates (gorillas, orangutans, chimpanzés ...). The sounds of these animals, caused by tickling, were emitted at the same time inspiring and exposing the air, something similar to a "huh-hah-ha".
"My friend told me: 'For my baby laughs like a monkey'" recalls the researcher Marishka Kret, professor of cognitive psychology.
"He taught me videos of his son, and the similarity was evident! I proposed him immediately to a vocalization expert colleague who made a study together," he explains to AFP.
A team of experts in cognitive neuroscience, which Kret directs with Diane Venneker at the University of Leyde in Holland, carried out various experiences, whose results were published on Wednesday in Royal Society Biology Letters.
The researchers heard recordings of human babies between 3 and 18 months to a first group of 15 expert phonetists and 102 novices (previously trained).
The participants had to measure the proportion of inspirations and expirations contained in the sounds, and then evaluate, on a scale of notation, to what extent they seemed like these pleasant and contagious laughter.
Among human adults, on the other hand, according to Mariska Kret, the laughter is a product in 74% expiration: they take air and then proffer some "ha ha" who are gradually losing force.
The experience showed that as babies grew, the proportion of expired air increased and with it the positive perception by the adult. "It is what surprised us more: to discover that a more 'mature laugh was perceived as more pleasant and contagious," said the researcher.
Two supplementary experiences with new recordings and groups confirmed the finding: the "ha ha ha" adults are more communicative.
"With the expiration, the signal seems clearer. The sound is not only stronger, but also more controlled, which allows you to indicate to the interlocutor: 'Hey, this is fun, continue!", Create Professor Kret.
Now you have to elucidate why babies pass from "Hu-Ha-Hu" to "ha ha ha". One of the explanations would be that they mislead their vocal capabilities, which are progressively developed, to adapt to complex faculties such as language.
And then there is sociability. As it is built, the child understands that he has to learn to "laugh better" to get to understand by his parents. When there are laughter in between, social interactions last longer. And that also applies to primates.
"When the monkeys laugh at an unexpected event, like a somerrette, they show their hilarity, which is quickly imitated," he explains.
But his vocal organs do not evolve as that of human beings, since they do not speak. And so its laughter stays eternally in a primary state, like that of a baby.Updated Date: 05 September 2021, 01:12