Why humans have more voice control than any other primates
A crying baby, a screaming adult, a teenager whose voice cracks — people could have sounded this shrill all the time, a new study suggests, if not for a crucial step in human evolution.
It’s what we’re missing that makes the difference. Humans have vocal cords, muscles in our larynx, or voice box, that vibrate to produce sound. But unlike all other studied primates, humans don’t have small bits of tissue above the vocal cords called vocal membranes. That uniquely human trait helps people control their voices well enough to produce the sounds that are the building blocks of spoken language, researchers report in the Aug. 12 Science.
Vocal membranes act like a reed in a clarinet, making it easier for some animals to shout loud and shrill. Think of the piercing calls of howler monkeys. When researchers used MRI and CT scans to look for vocal membranes in 43 different primate species, the scientists were surprised by what they saw: All primates except humans had the tissue.
That loss of vocal membranes would have been a “very major, very revolutionary event in human evolution,” says Takeshi Nishimura, a paleontologist at Kyoto University in Japan. [Continue reading…]