For the first time, researchers have demonstrated that non-human primates possess a tongue and a larynx that enables them to produce a series of vowel-like sounds similar to humans, indicating that they may have had the physical capability for language for several million years.
Writing in the journal PLOS One, a group of French researchers explained that by studying the vocalizations of 12 female and three male baboons living in an outdoor enclosure, they managed to pinpoint sounds comparable to the human vowels A, E, I, O and U in some of their calls.
“This is the first time we have shown this in a non-human primate,” said co-author Joel Fagot, a researcher at France’s National Center for Scientific Research, explained to AFP. He added that the discovery “suggests that human speech has a very long evolutionary history” and most likely had already begun long before the evolution of the modern human.
While many experts believe that language began within the last 70,000 to 100,000 years, Fagot and his colleagues report that the articulation skills required for speech could be up to 25 million years old and might date back to the Cercopithecoidae, the last common ancestor of humans and non-human primates such as baboons.
Tongue control, not larynx placement, most important factor
Previously, scientists believed that nonhuman primates were incapable of producing vowel-like sounds because their larynxes were located far higher in the neck than the human voice box, the Los Angeles Times noted. Recently, however, that theory has come under fire, as scientists have found lowered larynxes in other species incapable of producing vowel sounds.
The larynx-placement theory was typically used to support “the theoretical claim of a recent date for language origin, e.g. 70,000-100,000 years ago,” the study authors wrote. “It also diverted scientists’ interests away from articulated sound in nonhuman primates as a potential homolog of human speech, and thus lent support to less direct explanations of language evolution, involving communicative gestures, complex cognitive or neural functions, or genetics.”
Thanks to recent developments in computer modeling, experts have discovered that controlling and moving the tongue’s position is more important than voice box placement when it comes to producing vowels, and by an analyzing five types of vocalizations produced by baboons, Fagot’s team found that the primates appear to be capable of producing “vowel-like segments.”
Specifically, the Times said, the researchers analyzed the baboons’ grunts, wahoos, barks, yaks and mating calls – types of vocalizations which appeared to feature “formants” or concentrations of acoustic energy found in a vowel that can review the configuration of the mouth that produced it. They studied 1,335 spontaneous vocalizations and, after splitting the wahoos into the wa- and hoo- subunits, they identified 1,404 vowel-like vocalizations produced by the primates.
Furthermore, the newspaper added, the researchers verified that the creatures had the physical capacity to produce these sounds by dissecting and studying the tongues of two already deceased baboons. The findings suggest that the ability to produce vowel-like vocalizations are as much as 25 million years old, and that the ability to create distinct vowels improved over time, explaining why only humans are currently capable of producing full spoken language.
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