[LUM#6] The Origins of Speech
Baboons produce sounds that are quite similar to human vowels. And this is despite the fact that their vocal tract differs from ours. This discovery challenges a long-held belief and suggests that the emergence of speech may be much older than previously thought.
How did our distant ancestors first begin to speak? It’s a tricky question, since we have only fossils to go on, with no audio recordings available. Until now, the theory widely taught for decades was clear: only Homo sapiens could speak, from an anatomical standpoint. Its low-set larynx is thought to have played a crucial role in the ability to articulate distinct sounds. However, this low-set larynx is unique to humans, as all our primate cousins have a high-set larynx. It was only after the acquisition of bipedalism that our ancestors’ larynx began to descend over the course of hundreds of thousands of years. This allowed them, according to the theory, to begin articulating sounds once the necessary cognitive abilities had been acquired. The anatomical ability to speak was thus seen as yet another unique trait of Homo sapiens within the animal kingdom.
Five proto-vowels
Over the past few decades, this widely accepted theory has come under some attack. Human babies, for example, can produce vowels despite having a high larynx. Neanderthals, too—who went extinct about 30,000 to 40,000 years ago—were not hindered by their larynx when articulating sounds… especially since it was likely located in the same position as that of modern humans. But now, this theory on the emergence of speech is finally collapsing, 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 baboons’ articulation patterns are conclusive. These primates produce proto-vowels—that is, sounds with vowel-like properties—and can articulate five distinct ones: “a,” “e,” “o,” “ou,” and one similar to “i.” These correspond to the basic vowels around which the majority of human languages are organized.
The building blocks of speech
Our primate cousins can even combine two proto-vowels to form sounds like “waou,” for example, with the “w” serving as a rudimentary consonant. Why is this so important? Because these sounds are fundamental to articulate speech. Found in all human languages, they provide the framework for syllables, which essentially consist of a consonant followed by a vowel. Baboons therefore possess the building blocks of speech.
“This is the first time it has been demonstrated that primates possess the necessary anatomical features to speak,” explains Guillaume Captier, a surgeon and professor of anatomy at the University of Montpellier.“In other words, if we humans had the vocal tract of baboons, combined with our brains and our neurological control, we would be able to pronounce vowels and thus speak.” These monkeys, incidentally, have exactly the same tongue muscles and vocal cords as humans. However, it is the positioning of the tongue relative to the palate that is central to speech.
Continuous process
The history of the emergence of speech is therefore much older than previously thought. The necessary building blocks likely 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 about 200,000 years ago, but an earlier member of the human genus such as Homo habilis ( Evidence of a proto-vocal system in baboons suggests pre-hominin precursors of speech, in PlosOne, 2017).
Speech, therefore, is no longer the exclusive domain of modern humans.“Of course, this isn’t language. But it is indeed a system of speech that baboons possess, in the sense that these are distinct sounds,” notes Guillaume Captier.“It wasn’t anatomical limitations that constrained the emergence of speech and language, but rather coordination and brain development.” This therefore likely occurred as a continuous process over hundreds of thousands of years (What Path to the Dawn of Speech?: A Reanalysis of Half a Century of Debates and Data in Light of Speech Sciences, Science Advances, 2019). A major milestone has thus been reached in better understanding and, one day, reconstructing the remarkable 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 obstruction. This results in a clear, harmonious sound. With a consonant, however, the air encounters an obstruction. The consonant results in a sound: 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 help modulate the sound. Nasal vowels (as in “pain,” “blanc,” “mont”), for example, are pronounced with the soft palate lowered: air passes through both the mouth and the nose. We can also study vowels from an acoustic perspective by performing a spectral analysis of the sounds. We can thus identify them by their frequency and amplitude—which is what was done for the study on baboon vocalizations.
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