Why can't monkeys talk? Their anatomy is 'speech-ready' but their brains aren't wired for it: neuroscientist (2024)

Why can’t monkeys talk?

For decades it has been a textbook fact that monkeys cannot speak because their throats and mouths are not set up for it. Their very anatomy prevents them from synchronizing diaphragm, tongue, cheeks and vocal cords in the way humans do when they talk. New research suggests this is precisely wrong, and the history of human language may look different as a result.

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Any visit to the zoo will demonstrate monkeys can coo and grunt. They can make simple, single utterances. But the elaborate phonetics of human speech — everything from the basic plosives (sudden shots of breath, like “p” and “t”) and fricatives (interrupted breath like “f” and “sh”) to the grandly trilled “r” sounds of Scotland or the clicks of Southern Africa —seem far beyond their physical abilities.

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I think people were pretty surprised that, in this speech-rich, language-rich environment, a chimpanzee couldn’t utter a single word. Like nothing

Talking, according to neuroscientist Asif Ghazanfar of Princeton University, is an “exquisite biomechanical coordination problem,” and the traditional view is that nonhuman primates do not have the muscles to solve it. Even if they knew language, on this view, monkeys and chimpanzees could not speak it out loud.

There are even experiments that purport to prove this, especially a 1969 paper by Phil Lieberman, based on cadaver research, which concluded the vocal apparatus of nonhuman primates is “inherently incapable of producing the range of human speech.”

A lot of evidence fits this view. No non-human primates have been able to produce speech, and not for lack of eager humans trying to teach them. Even chimpanzees raised from birth in human homes, just like human babies, fail miserably at what nearly every human baby manages with ease, from “goo-goo gaga” all the way to “Dad, you’re so embarrassing.”

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“I think people were pretty surprised that, in this speech-rich, language-rich environment, a chimpanzee couldn’t utter a single word. Like nothing,” said Ghazanfar. “They could do symbolic communication, but why weren’t they speaking?”

This question has relevance for humans, for whom language is a defining species-wide trait, credited for most if not all of civilization. If anatomy is what sets humans apart from other primates, then the evolution of modern speech must have required major anatomical changes. But if the difference is cognitive, the natural history of spoken language would suddenly look quite different.

To get at this problem, Ghazanfar and colleagues studied three monkeys. One, in particular, called Emiliano, was scanned in great detail using x-ray video, and a computer model created that could produce a variety of sounds based on his anatomy. Human participants helped the researchers by listening to the vowel sounds and confirming they spanned the human range. They even had the computerized monkey model speak a sentence, “Will you marry me?” which sounds odd but is clearly intelligible.

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Monkey anatomy, they claim to prove, is no obstacle to speech. The dominant view has been wrong, maybe even backwards. For nonhuman primates like monkeys and chimps, speaking is a problem of cognitive software, not muscular hardware.

“We conclude that if a macaque monkey had a brain capable of vocal learning and combinatoric operations over speech sounds, its vocal tract would be able to produce clearly intelligible speech,” they write in the paper, “Monkey vocal tracts are speech-ready” in the journal Science Advances. The lead author is W. Tec*mseh Fitch, an evolutionary cognitive biologist at the University of Vienna whose great-great-great grandfather, incidentally, was the American Civil War Union General William Tec*mseh Sherman.

There is an important comparison to parrots. Parrots speak without knowing the meaning of what they say. They learn vocalizations without grasping concepts. Monkeys seem to grasp some of the concepts, but lack virtually all the vocalizations.

“I’m just floored, basically, by the parrot stuff. I have no way of explaining it,” Ghazanfar said. Birds and primates are hard to compare because they are on a different evolutionary tracks, with different brain anatomy, and it is hard to find structural similarities between bird and mammal brains, let alone primates.

“It’s absolutely incredible what birds can do with their vocal anatomy,” he said.

Monkeys, less so. Science has always known they would talk if they could but they can’t so they won’t. According to this latest research, it just knew this for the wrong reason.

• Email: jbrean@nationalpost.com | Twitter: JosephBrean

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