A little membrane makes a big difference

A little membrane makes a big difference

Why, unlike other primates, are we able to produce such a wide variety of sounds? According to a new study in the journal Sciences The simpler architecture of our larynx has something to do with it.

Like other primates, we make sounds by making air from the lungs vibrate the vocal cords in the larynx. But these vibrations are much more stable and controlled in us than in many other mammals, allowing us to produce a wide range of sounds that form the basis of our language.

A lot of noise

In the new study, the scientists examined the throats of 43 species of primates, including gibbons, macaques and baboons, and great apes such as chimpanzees and gorillas. In all species of monkeys, they found a missing membrane in the larynx in humans.

To see the effect, they filmed tiny cameras in the throats of the calling monkeys, and pumped air through three throats removed from the dead chimpanzees. Finally, using a computer model, they simulated what would happen if we had such a membrane.

“This shows that the membrane allows for a lot of noise, but without improved tone,” says Bart de Boer, who studies speech development at Vrije Universiteit Brussel. “The disappearance of this thin membrane made it easier to control the heavy vocal cords, as well as the development of speech.”

least is more

About 6 to 7 million years ago, the ancestors of Homo sapiens and the ancestors of our closest relatives, chimpanzees, went their evolutionary way. The membrane fluttering in a chaotic manner should then be gone, but when exactly is not clear.

Of course, to make speech possible, other modifications were also necessary, such as lowering the larynx and conscious control of the vocal apparatus from the brain. “It appears that the loss of this membrane was an important step toward more complex communications,” says de Boer.

Somewhat ironically, our complicated speech also appears to be the result of a less complex larynx. Researcher Tecumseh Fitch (University of Vienna) concludes, “Our research shows that in evolution, less is sometimes more.”

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