Monkey Say, Monkey Do: Baboons Can Make Humanlike Speech Sounds
New research suggests our last common ancestor with these monkeys possessed the vocal machinery needed to speak
By Tanya Lewis on January 11, 2017
Credit: Derek Keats Flickr (CC BY 2.0)
To the untrained listener, a bunch of babbling baboons may not sound like much. But sharp-eared experts have now found that our primate cousins can actually produce humanlike vowel sounds. The finding suggests the last common ancestor of humans and baboons may have possessed the vocal machinery for speech—hinting at a much earlier origin for language than previously thought.
Researchers from the National Center for Scientific Research (CNRS) and Grenoble Alpes University, both in France, and their colleagues recorded baboons in captivity, finding the animals were capable of producing five distinct sounds that have the same characteristic frequencies as human vowels. As reported today in PLoS ONE, the animals could make these sounds despite the fact that, as dissections later revealed, they possess high voice boxes, or larynxes, an anatomical feature long thought to be an impediment to speech. “This breaks a serious logjam” in the study of language, says study co-author Thomas Sawallis, a linguist at the University of Alabama. “Theories of language evolution have developed based on the idea that full speech was only available to anatomically modern Homo sapiens,” approximately 70,000 to 100,000 years ago, he says, but in fact, “we could have had the beginnings of speech 25 million years ago.”
The evolution of language is considered one of the hardest problems in science, because the process left no fossil evidence behind. One practical approach, however, is to study the mechanics of speech. Language consists roughly of different combinations of vowels and consonants. Notably, humans possess low larynxes, which makes it easier to produce a wide range of vowel sounds (and as Darwin observed, also makes it easier for us to choke on food). A foundational theory of speech production, developed by Brown University cognitive scientist Philip Lieberman in the 1960s, states the high larynxes and thus shorter vocal tracts of most nonhuman primates prevents them from producing vowel-like sounds. Yet recent research calls Lieberman’s hypothesis into question.
For one thing, scientists have discovered that a number of other species besides humans, including chimpanzees and some types of deer, possess low larynxes. In addition, babies can produce vowel sounds despite the fact their larynxes have not yet descended, and studies of Neandertals, who also have high larynxes, have suggested these ancient humans may have had the ability to produce such sounds as well. Moreover, scientists now think that the way the tongue muscle and lips constrict the airway is more important for producing speech than the position of the larynx.AlreadyInUse, PADemD, broiles and 2 othersKauaiK, tularetom like this
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