The ancestors of homo sapiens were perhaps also endowed with speech. This is explained by a team of scientists in an article published in the journal Science Advance, Wednesday, December 11, to dismantle a theory that dominates the debates around the origin of speech for fifty years.

"The dawn of the word could go back to about 20 million years and not 200 000 years [date of appearance of homo sapiens, Editor's note]", write the authors, a team made up of French and Canadian researchers .

A story of larynx and pharynx

How could one have been mistaken for more than 19 million years to date the beginnings of such an important characteristic of the human race? The fault is Philip Lieberman, one of the American pioneers of the study of the emergence of speech. In analyzing the corpse of a monkey in the late 1960s, he found that the larynx is higher than the adult man in the vocal tract, so that he also has a smaller pharynx. Idem in infants and, according to these analyzes, it would be the same for the Neanderthal man. According to him, if monkeys can not talk, it's because they do not have the larynx in the right place. This anatomical lock would prevent them from producing the vowels i / a / or that are present in all the languages ​​of the world.

This discovery gave birth in 1971 to the theory of the descent of the larynx, which would make this small physical detail the key to understanding the origin of speech. Since the larynx has found its current place with homo sapiens, primatologists have made it the year 0 of spoken language.

Since the 1980s, this explanation has been questioned, but it has had a hard skin and it remained the dominant theory until the years 2010. "This is a very attractive theory because it is easy to understand and, with very little - an anatomical detail - Philip Lieberman explained a lot ", summarizes Louis-Jean Boë, one of the authors of the article Science Advance and researcher at the University of Grenoble Alpes, contacted by France 24.

Baboons and vowels

It was also difficult to disassemble. The counter-offensive of the linguists has taken place in three stages in recent years. They first managed to prove that a child of one year was able to produce these famous vowels even if his larynx was not yet in the "right place", according to Lieberman's theory.

Everything depends, in fact, on the position of the language. This was the second step: to demonstrate "the importance of the control of articulators [as the language, Ed] rather than the position of the larynx," says Louis-Jean Boë. By proving that by mastering the position of the language, we can produce the i / a / or [/ i /, / a /, / u /], the turn is played, "because these vowels are like the primary colors, if we can pronounce them, we can master all the others, "notes this engineer and linguist.

The baboons of Joël Fagot's Laboratory of Cognitive Psychology (AMU, CNRS) Caralyn Kemp and Julie Gullstrand

There was still the problem of the monkey. The solution came from the observation of baboons in a laboratory in Marseille. "For a year, their vocalizations were recorded while they were evolving in different communication situations," says the French researcher. The analysis of these data, using new techniques of signal processing and normalization to better decipher these vocalizations, enabled them to see that they did indeed produce that they did indeed produce similar sounds. to vowels.

The interest of this discovery is twofold: not only does it help to defeat the theory of Philip Lieberman, but most importantly, the baboons belong to the family of primates who, about 20 million years ago, separated from their cousins, the great apes, from which humans descend. The vocal apparatus of the baboons has evolved very little, which suggests that in these very remote times the great family of primates already had all the necessary to be gifted with speech.

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