How quirk of primate evolution gave humans the voice apes lack - The Guardian

Simplification of larynx let humans have excellent pitch control with long and stable speech sounds.

Researchers said on Thursday that an examination of the voice box, or larynx, in 43 species of primates showed that humans differ from apes and monkeys in lacking an anatomical structure called a vocal membrane: small, ribbon-like extensions of the vocal cords.

This simplification of the larynx enabled humans to have excellent pitch control with long and stable speech sounds, they said.

“We argue that the more complicated vocal structures in nonhuman primates can make it difficult to control vibrations with precision,” said primatologist Takeshi Nishimura of Kyoto University’s Centre for the Evolutionary Origins of Human Behaviour in Japan, lead author of the research published in the journal Science.

“Vocal membranes allow other primates to make louder, higher-pitched calls than humans – but they make voice breaks and noisy vocal irregularity more common,” said evolutionary biologist and study co-author W Tecumseh Fitch of the University of Vienna.