Why did humans develop the ability to speak and speak without other primates? The answer is unexpected
Until now, researchers had not found logical explanations for what happened during our evolution and distinguished us from monkeys, although the composition of the structures of the vocal apparatus in humans is almost identical to that of other primates
A new study published Thursday in the journal Science claims to have found the most unexpected answer.
Scientists have always baffled the issue of speech and speech in humans without all other creatures. Why did humans develop the ability to talk while monkeys, for example, continued to communicate with their own shouts and sounds? Unable to reproduce the sounds of human speech?
Until now, researchers had not found logical explanations for what happened during our evolution and distinguished us from monkeys, although the composition of the structures of the vocal apparatus in humans is almost identical to that of other primates.
But a new study published Thursday in the journal Science claims to have found the most unexpected answer.
When analyzing the vocal tract — the larynx — of 43 primate species, a team of researchers in Japan found that all non-human primates — from orangutans to chimpanzees — had an extra feature in their throats that humans didn't.
While both humans and non-human primates produce sounds by forcing air through their larynxes, causing folds of tissue to vibrate, monkeys have an additional feature, a thin tissue known as the vocal cords, or vocal lips.
Compared to apes, humans have been found to lack this anatomical vocal cord - a small muscle above the vocal cords - as well as the balloon-like laryngeal structures called air sacs, which apes use to emit shrill calls and shrieks that we humans are unable to produce.
According to the researchers, humans lost this extra vocal tissue over time, which somehow simplified and stabilized the sounds coming from our throats, allowing us, in time, to develop the ability to speak and eventually to develop very complex languages.
On the other hand, monkeys have preserved these vocal membranes, which do not allow them to control the reflex, register their voice and produce stable and clear vocal fold vibrations.
"Ironically, the increasing complexity of spoken human language follows the simplification of the anatomy of our larynx," the study says.
It is unclear when humans lost this extra tissue, which is still found in apes, and when they became able to speak. The soft tissues of the larynx have not been preserved in fossils, and researchers can only study living species.
But what we do know is that this may have happened sometime after the Homo sapiens line separated from other primates, about 6 or 7 million years ago.
But does the fact that apes have not developed the ability to speak like humans mean that they are unable to communicate clearly with each other? Yes, they are able.
Although their vocal anatomy does not allow them to form vowel sounds and appropriate words, non-human primates have a complex communication system that relies primarily on body language rather than oral sounds.
But monkeys have also proven their ability to communicate with humans.
The gorilla Koko, for example, was famous for its ability to use over 1,000 hand signs in sign language, while the bonobo Kanzi was able to communicate using a keyboard.
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