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WASHINGTON, Dec. 13 (Xinhua) -- A recent study shows that monkeys have the vocal tracts required to talk like humans, but the limitations that keep nonhuman primates from speaking are in their brains.
For decades, the inability of nonhuman primates to produce human speech sounds has been claimed to stem from limitations in their vocal tract anatomy, but the study published in the December issue of the journal Science Advances suggested otherwise.
Using x-ray videos, the team of scientists led by Tecumseh Fitch at the University of Vienna and Asif Ghazanfar at Princeton University, analyzed the mouth and throat of macaque monkeys while they vocalize, consume food and create facial expressions.
The researchers find that the macaque vocal tract could easily produce an adequate range of speech sounds to support spoken language and is more flexible than what scientists previously thought.
Based on observed vocal tract configurations of macaque monkeys, the researchers computed a synthesized monkey version of the phrase "Will you marry me?" and other human speech utterances.
Although this effect is audible and sounds like a slight indistinctness or foreign accent, the monkey version of such phrases is still clearly understandable, the study said.
"No one can say now that there's a vocal anatomy problem with monkey speech. They have a speech-ready vocal anatomy, but not a speech-ready brain. Now we need to find out why the human but not the monkey brain can produce language," Ghazanfar told New Scientist.
However, the researchers admitted that they do not claim macaque speech would sound precisely like human speech.
Rather, the results definitively show that the phonetic range inherent in a macaque vocal tract, based on actual observed vocal tract configurations, would itself pose no impediment to linguistic communication if macaques had human-like neural control systems, the study said.
In short, primates have a speech-ready vocal tract but lack a speech-ready brain to take advantage of its latent operating range, it concluded.
