Published: Sun, January 15, 2017
Science | By Boyd Webster

Guinea Baboons Can Produce Sounds Comparable To Human Speech

Guinea Baboons Can Produce Sounds Comparable To Human Speech

"It also diverted scientists' interests away from articulated sound in nonhuman primates as a potential homolog of human speech, and thus lent support to less direct explanations of language evolution, involving communicative gestures, complex cognitive or neural functions, or genetics".

Writing in the journal PLOS One, a group of French researchers explained that by studying the vocalizations of 12 female and three male baboons living in an outdoor enclosure, they managed to pinpoint sounds comparable to the human vowels A, E, I, O and U in some of their calls. The findings bolster a recent study showing that Japanese macaques are also anatomically capable of speech.

While many experts believe that language began within the last 70,000 to 100,000 years, Fagot and his colleagues report that the articulation skills required for speech could be up to 25 million years old and might date back to the Cercopithecoidae, the last common ancestor of humans and non-human primates such as baboons.

The scientists analyzed the recordings looking for "formants" - concentrations of acoustic energy around key frequencies in human speech, and whose distribution is defined by the shape of our vocal tract. Fitch was also the lead author of the Macaque study. "It was thought that in order to pronounce vowels, you had to have a low larynx [voice box], as humans do", he says. Other primate species, such as monkeys and great apes, have lower larynxes that have been thought incapable of producing the full range of vowels. "You can't have language without them".

So why couldn't other primates do the same?

The detailed findings were published online January 11 in the journal PLOS ONE.

The scientists ended up analyzing five types of vocalizations that also appeared to feature formants - grunts, wahoos, barks, yaks and mating calls.

A recent study conducted by Louis-Jean Boë of Grenoble Alpes University, France, and colleagues, published on Jan.11, 2017 concluded that baboons can make five vowel-like sounds similar to the ones spoken by humans.

This research resolves a kind of paradox in baboon vocalization, Dr. Fagot says, in a phone interview with The Christian Science Monitor. This suggests that these monkeys likewise use tongue movements to form each of the vowel-like sounds. That doesn't mean they have a language, which requires a structure with rules for combining those sounds, but, says Fagot, they have some of the building blocks for it.

Vowels are produced by manipulating the vocal tract and are thought to be particularly hard to produce for animals with vocal tracts distinct from ours, explains Thore Jon Bergman, an evolutionary biopsychologist at the University of MI who was not part of the baboon study. And for a long time, many researchers assumed that nonhuman primates couldn't make vowel-like sounds because their larynxes (or voice boxes) sat much higher in the neck than human larynxes do. It is this ability to control the tongue, rather than the position of the larynx, that is key to producing vowellike sounds, the researchers note.

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