[LUM#6] The origins of speech
Baboons make sounds that are very similar to human vowels, despite their vocal tract being different from ours. This discovery breaks with conventional wisdom and suggests that the emergence of speech may be much older than previously thought.
How did our distant ancestors begin to speak? This is a difficult question to answer, as we only have fossils to go on, with no recordings available. Until now, the theory widely taught for decades was clear. Only Homo sapiens could speak, from an anatomical point of view. Their low larynx played a crucial role in enabling them to articulate distinct sounds. However, this low larynx is unique to humans, as all our primate cousins have a high larynx. It was only after acquiring bipedalism that our ancestors' larynx began to descend over hundreds of thousands of years. According to the theory, this enabled them to begin articulating once they had acquired the necessary cognitive abilities. The anatomical ability to speak was thus perceived as yet another unique feature of Homo sapiens in the animal kingdom.
Five proto-vowels
In recent decades, this widely accepted theory has come under attack. Human babies, for example, can pronounce vowels despite their high larynx. Neanderthals, who disappeared around 30,000 to 40,000 years ago, were not hindered by their larynx when it came to articulation, especially since it was probably located in the same position as that of modern humans. But now, this theory on the emergence of speech has been definitively disproved, following a study conducted by several teams of researchers.
In recordings of 1,400 vocalizations produced by baboons, many sounds are comparable to human vowels. Analyses of their acoustic properties and the way baboons articulate them are conclusive. These primates emit proto-vowels, i.e., sounds that have the properties of vowels, and they can articulate five distinct ones: "a," "e," "o," "ou," and one close to "i." These correspond to the basic vowels around which most human languages are organized.
Building blocks of speech
Our primate cousins can even combine two proto-vowels to form "waou," for example, with the "w" constituting an early form of a consonant. Why is this so important? Because these sounds are fundamental to articulated speech. Present in all human languages, they provide a framework for syllables, essentially a consonant followed by a vowel. Baboons therefore possess the basic building blocks of speech.
"This is the first time that primates have been shown to have the anatomical elements necessary for speech," explains Guillaume Captier, surgeon and professor of anatomy at the University of Montpellier. "In other words, if we humans had the vocal tract of baboons, with our brains and neurological control, we would be able to pronounce vowels and therefore speak." These monkeys, incidentally, have exactly the same tongue muscles and vocal cords as humans. However, it is the position of the tongue in relation to the palate that is central to speech.
Continuous process
The history of the emergence of speech is therefore much older than we thought. The basic elements required probably date back to our last common ancestor with the baboon, 25 million years ago. The first human to begin using spoken communication may therefore not have been Homo sapiens, who appeared around 200,000 years ago, but an earlier representative of the human genus such as Homo habilis ( Evidence of a proto-vocal system in baboons suggests pre-hominine precursors to speech, in PlosOne, 2017).
Speech, therefore, is no longer reserved for modern humans."Of course, this is not language. But it is a system of speech, which baboons have, in the sense that they are differentiated sounds," says Guillaume Captier. "It was not anatomical limitations that constrained the emergence of speech and language, but coordination and brain development." This therefore undoubtedly took place as a continuous process over hundreds of thousands of years (What path to the dawn of speech?: Reanalyzing half a century of debates and data in light of speech science, ScienceAdvances, 2019). A major step has thus been taken towards better understanding and, one day, reconstructing the incredible epic of the emergence of human speech and language...
What is a vowel?
When we pronounce a vowel, air flows freely through the mouth and nasal passages, encountering no obstacles. This results in a clear, harmonious sound. With a consonant, however, the air encounters an obstruction. The consonant results in a noise: a click, a hiss, a whistle, a roll, etc. What exactly happens when we produce a vowel? The sound comes from the vibration of our vocal cords. At the same time, the tongue, soft palate, teeth, and lips come into play to modulate the sound. Nasal vowels (as in "pain," "blanc," "mont"), for example, are pronounced with the soft palate lowered: air passes through the mouth and nose. Vowels can also be studied from an acoustic point of view by performing a spectral analysis of the sounds. They can thus be recognized by their frequency and amplitude—which was done for the study on baboon vocalizations.
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