It’s something of a tragedy that we cannot converse with our primate cousins. With so much in common, there would surely be plenty to talk about It has long been pondered why our closest relatives are incapable of speech. And, according to new research, one fashionable possibility can now be ruled out. There are two broad explanations to account for non-human primates’ lack of conversational skills. One is that their vocal tracts cannot form the variety of sounds required. The other is that their brains and nervous systems are not wired up to control the sounds. The new study analyses the anatomy of the vocal tracts of rhesus macaques and finds that their larynx, vocal chords, mouth and tongue should be quite capable of producing the range of vowel and consonant sounds required to mimic human speech.
Tecumseh Fitch of the University of Vienna, who led the research, told BBC Wildlife that he would expect great apes to be even more suited to speech – anatomically, at least. “Apes have better and more voluntary control over their vocal tract – lips, tongue and jaws – than monkeys,” he explained. It remains far from clear, though, precisely what their nervous systems are lacking. Let’s suppose, for example, that if s possible to provide a primate with the wiring required to finely control its vocalisations. Would it then be able to speak?
“If you just gave it the wiring for vocal control, it could mimic words and imitate sounds, like a mynah bird or parrot – which no monkey has ever done – but not ‘speak its mind’,” said Fitch. That’s because language also requires other complex neurological circuitry before a real conversation is possible. “I’m sure monkeys would have lots to say if they had the full package of speech, syntax and semantics that underlies language,” said Fitch “All the cognitive work shows that monkeys know a lot about the world: about other monkeys, about food, about locations, etc. But that would require more than just vocal control.”