Scientists have identified evolutionary modifications in the voice box distinguishing people from other primates that may underpin a capability indispensable to humankind – speaking.
Researchers said on [August 11] an examination of the voice box, known as the 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.
Humans also lack balloon-like laryngeal structures called air sacs that may help some apes and monkeys produce loud and resonant calls, and avoid hyperventilating, they found.
“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 in Austria.
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Fitch said it is possible the laryngeal simplification arose in a human forerunner called Australopithecus, which combined ape-like and human-like traits and first appeared in Africa roughly 3.85 million years ago, or later in our genus Homo, which first appeared in Africa about 2.4 million years ago. Homo sapiens originated more than 300,000 years ago in Africa.
