Living in trees may have given great apes vocal skills for consonants

A comparability of consonant-like sounds in nice apes suggests an arboreal life-style might have been a step in the direction of advanced speech in our ancestors

By Richard Kemeny

Our advanced speech might have originated from life within the bushes. The first evaluation of the evolution of consonants suggests their roots could also be linked to an arboreal life-style, hinting that our ancestors spent extra time in bushes than presently thought.

All human language makes use of a mix of vowels and consonants to switch info. Most primates talk virtually solely utilizing vowel-like calls, however non-human nice apes produce consonant-like sounds to various levels.

This raises the query of the place consonants come from, says Adriano Lameira on the University of Warwick within the UK. To discover out, Lameira combed by means of present literature to see how widespread consonants are among the many nice apes and if this might make clear their evolutionary origin.

He discovered that wild orangutans, which spend most of their time within the forest cover, produce a higher quantity and number of consonant sounds than wild gorillas, chimpanzees and bonobos, which reside on the bottom. Only in orangutans are these sounds common.

“Orangutans have this rich repertoire of kiss sounds, scrapes and clicks and raspberries and smacks,” says Lameira. They usually use these sounds whereas constructing nests, or speaking with their younger, or as alarm calls.

Lameira thinks that dwelling within the bushes might clarify why orangutans have advanced this broad vocal repertoire. Great apes are adept at extracting hidden or protected meals, like nuts, a talent that usually requires using instruments. While foraging up within the cover, nevertheless, orangutans should at all times use not less than one arm to take care of stability. They have due to this fact developed extra advanced management of their lips, tongue and jaws to make use of their mouths as a “fifth limb” — orangutans can peel an orange simply by utilizing their lips, for instance.

As an evolutionary aspect impact, this superior motor talent gave orangutans an elevated skill to provide consonant-like sounds, argues Lameira. This may imply that our early ancestors developed consonant sounds whereas hanging round within the bushes, too.

“There’s a growing sense that our dependency on trees was much larger and deeper than we think,” says Lameira, which works in opposition to the concept that people began strolling upright as they moved into the savannah. “Within that mosaic that was emerging, we might actually have stayed where the trees were and crossed from one patch to the other as quickly as we could.”

The hyperlink between feeding and vocal communication doesn’t apply to smaller tree-dwelling primates akin to monkeys, says Lameira, as a result of they’re extra secure on tree branches and don’t forage in the identical method.

“The arboreal origin of consonants is an interesting hypothesis worth testing,” says Chris Petkov at Newcastle University, UK, although he questions some points. He says many monkeys use grunts, that are akin to consonants. And as people aren’t tree-dwelling, there should be different the reason why consonants persevered, akin to rising social networks driving an enlargement of name sorts. These hypotheses may very well be examined by characterising consonant-like vocalisations extra systematically throughout species.

“Given that we do not know what led to the evolution of consonants, I think testing this hypothesis can potentially provide some insights,” says Serge Wich at Liverpool John Moores University within the UK. “Of course, we have to remain very cautious that even if there would be a relationship that this does not mean causality as there could be other factors involved.”

Journal reference: Trends in Cognitive Sciences, DOI: 10.1016/j.tics.2022.11.012

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