Baboons make five human-like vowel sounds

GRENOBLE, France, Jan. 12 (UPI) -- Researchers have previously suggested the low human larynx is essential to human language, as it allows humans to make vowel sounds. The high larynx, or voice box, of nonhuman primates, the thinking goes, prevents our closest relatives from making the vowel sounds necessary for language.

New research suggests, despite their high larynx, baboons can make at least five human-like vowel sounds.

"Theories of language evolution have developed based on the idea that full speech was only available to anatomically modern Homo sapiens," Thomas Sawallis, a linguist at the University of Alabama, told Scientific American. "We could have had the beginnings of speech 25 million years ago."

Sawallis is co-author of the new study on baboon vocalizations, published in the journal PLOS ONE. The research was led by a group of scientists from Grenoble Alpes University in France.

Researchers recorded and analyzed 1,335 spontaneous vocalizations produced by 15 Guinea baboons, three male and 12 female. An acoustic analysis using linear predictive coding allowed scientists to identify five sounds with a sequence of frequencies similar to human vowel sounds.

The analysis suggests baboons, like humans, use precise control of their tongue position to produce vowel sounds. When researchers dissected the vocal chords, voice box and tongue of two baboons who died of natural causes, they found the primates have tongue muscles comparable to humans.

Until recently, researchers believed the anatomical potential for speech was a relatively modern development, emerging between 70,000 and 100,000 years ago. The latest research suggests the physical capacity for speech has been around for 25 million years.

Another study, published in 2016, offered a similar conclusion. Its authors argued neural shortcomings, not physical limitations, prevent primates from using language.