The speech of ancient hominids might have originated thanks to living in trees, suggests study
(Kabir Bakie / Wikimedia Commons https://bit.ly/3QG5SO5)
A comparison of the calls of gorillas, chimpanzees and orangutans showed that there are much more consonant sounds in the vocal repertoire of orangutans living in trees.
According to the researchers lead by Adriano Lameira from the University of Warwick, this is no accident.
The team believes that the arboreal lifestyle helped develop the speech of our ancient ancestors.
All languages in the world are made up of vowels and consonants, but animals more often make sounds similar to vowels.
We still don't know how and when consonants (or something similar), and then speech, arose.
But in the vocal repertoire of hominids, a family of primates that includes humans and great apes, consonants do occur.
Therefore, in order to understand the evolution of consonants, scientists study the calls of such apes.
Lameira’s team has been observing orangutans for many years and studying their calls and other forms of vocalization.
Now, relying on his work and the research of other scientists, they offer a version of the origin of consonants… and subsequently human speech.
In a new article, he compares the vocal repertoire of orangutans, chimpanzees and gorillas.
In captivity, all great apes can invent new sounds (including those similar to consonants) by observing relatives or people.
But in nature, the sound repertoire of monkeys from different genera can vary greatly.
So, wild orangutans make sounds resembling consonants in completely different contexts, from building a nest to communicating with cubs.
In general, the consonant-like calls of orangutans are social, cultural, and occur in a variety of contexts, just as they do in human speech.
Wild gorillas, chimpanzees, and bonobos have lower consonant repertoires.
Only some populations of gorillas have a single supposedly cultural consonant, while others do not.
Individual populations of wild chimpanzees make one or two consonant-like sounds during social grooming.
The way of life of great apes is different.
Orangutans live in the rainforests of the islands of Sumatra and Kalimantan and spend most of their lives in trees.
This is different from most terrestrial African gorillas and chimpanzees, which combine both.
It is the way of life and the associated food ecology that can explain the ubiquity of their consonant-like cries.
According to Lameira, it's all about the handling of the food.
All hominids are skilled foragers, their cognitive and motor abilities allow them to extract and crack nuts, peel fruits, and so on.
To do this, monkeys sometimes use tools; chimpanzees, for example, can hit nuts on the ground or knock stones on them, but this requires a solid support like the ground.
It is not very convenient for orangutans in trees to manipulate food: at least one of their limbs is probably busy holding on to a branch.
Therefore, they began to use the mouth as a "fifth hand" to hold or process food.
Because of this, the neuromotor control of the lips, lower jaw and tongue is very well developed in orangutans.
They can peel an orange with their lips alone, and in captivity pass objects that a person gives them by mouth, although their lifestyle there is more terrestrial.
Apparently, it was the improved oral motor skills that allowed the orangutans to reproduce deaf consonant sounds: clicks, crackles, hisses, the sound of kisses.
Vowel sounds are almost always voiced, and when we pronounce them, the larynx and vocal folds are involved.
But for consonants, supraglottic articulators are needed: lips, tongue, and lower jaw.
The appearance of consonant sounds in ancient hominids eventually led to the formation of speech - instead of the previous monkey cries.
And it can be assumed that this happened due to the arboreal way of life of human ancestors.
This is consistent with the hypothesis that bipedalism also arose in trees as an adaptation to moving along flexible branches.
At the same time, non-human great apes living in captivity, despite the earthly way of life, still invent and imitate consonant sounds.
This suggests that the vocal repertoire is formed, among other things, through training and practice.
And, most likely, the formation of speech in our ancestors was influenced by all factors at once: innate and epigenetic, environmental and social.
- Trends in Cognitive Sciences: https://linkinghub.elsevier.com/retrieve/pii/S1364661322002972
- Eureka Alert: https://www.eurekalert.org/news-releases/974268
- New Scientist: https://www.newscientist.com/article/2352503-living-in-trees-may-have-given-great-apes-vocal-skills-for-consonants/
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