Researchers have been studying the vocal tracts of the macaque monkey and have found that they are more than capable of speaking. However, it seems their brains just aren’t up to the task.

This means how humans evolved to speak languages is down to cognitive abilities rather than physical.

The researchers involved in the study used X-ray equipment to analyze the inner workings of the macaque monkey’s mouth specifically the movements of the tongue, lips and larynx while the monkeys were vocalizing. From this information, they then created possible vocal simulations using a model which showed that the monkeys are actually capable of making sounds and sentences if they had the cognitive ability to do so.

“Now nobody can say that it’s something about the vocal anatomy that keeps monkeys from being able to speak — it has to be something in the brain,” stated Asif Ghazanfar, a professor of psychology at Princeton University. “Even if this finding only applies to macaque monkeys, it would still debunk the idea that it’s the anatomy that limits speech in nonhumans.”

The study into vocalization in monkeys will help towards understanding the role cognition plays in developing language and comparing the brains of chimps to macaques could pinpoint the emergence of language itself.

“The paper opens whole new doors for finding the key to the uniqueness of humans’ unparalleled language ability,” said Laurie Santos, a psychology professor at Yale University who did not participate in the study. “If a species as old as a macaque has a vocal tract capable of speech, then we really need to find the reason that this didn’t translate for later primates into the kind of speech sounds that humans produce. I think that means we’re in for some exciting new answers soon.”

Details of the study were published in the journal Science Advances.