Study: Evolutionary Changes in Voice Box May Have Led to Human Speech
2022-08-15
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1Scientists say changes in the voice box of nonhuman primates over time may have led to human speech.
2The researchers said they examined the voice box, also known as the larynx, in 43 different species of primates.
3Their study showed that humans differ from apes and monkeys because humans lack a structure called a vocal membrane.
4This contains small, muscular attachments to the vocal cords.
5The researchers said humans also lack balloon-like structures called air sacs that may help some apes and monkeys produce loud, deep calls.
6The air sacs also help the primates avoid hyperventilating, which means to breathe an unusually fast rate.
7The scientists said the loss of these tissues resulted in a stable vocal system in humans that was critical to the development, or evolution, of human speech.
8Such speech permits humans to express thoughts and feelings using clear and complex sounds, the team said.
9Humans are primates, as are monkeys and apes.
10The evolutionary lineage that led to our species, Homo sapiens, split from the one that led to our closest living relatives, chimpanzees, about 6-7 million years ago.
11The researchers say the voice box changes are believed to have happened after that.
12Takeshi Nishimura is with Kyoto University's Center for the Evolutionary Origins of Human Behavior in Japan.
13He was a lead writer of the study, which recently appeared in the publication Science.
14Nishimura said the research suggested that complex vocal structures in nonhuman primates can make it difficult to effectively control vibrations.
15Another lead researcher, Tecumseh Fitch of Austria's University of Vienna, added that vocal membranes permit other primates to make louder, higher calls than humans.
16"But they make voice breaks and noisy vocal irregularity more common," he said.
17The larynx is a tube in the throat that is connected to the top of the windpipe and contains the vocal cords. It is used for talking, breathing and swallowing.
18"The larynx is the organ of voice, which creates the signal we use to sing and speak," Fitch said.
19Only living species were included in the study because these soft tissues are not likely to appear in fossils, the remains of ancient life.
20This means that it is unclear exactly when the changes took place.
21Fitch said it is possible the simplified development happened in a human ancestor called Australopithecus, which combined ape-like and human-like elements.
22Scientists believe Australopithecus first appeared in Africa about 3.85 million years ago.
23The research team said the changes could have happened later in our ancestor grouping Homo, which first appeared in Africa 2.4 million years ago.
24Homo sapiens - the primate species human beings belong to - appeared more than 300,000 years ago in Africa.
25Fitch noted, however, that while the evolutionary simplification of the larynx was important, it "did not give us speech by itself."
26He noted that other body developments also mattered for speech over time, including a change in the position of the larynx.
27"Speech and language are critically related, but not synonymous," said Harold Gouzoules. He is a primatologist and psychologist at Emory University in Atlanta, Georgia.
28"Speech is the audible sound-based manner of language expression - and humans, alone among the primates, can produce it," he wrote in a related commentary in Science.
29The researchers noted that the increased complexity of human spoken language came as a result of evolutionary simplification.
30"I think it's pretty interesting that sometimes in evolution 'less is more,'" Fitch said.
31He added, "By losing a trait, you might open the door to some new adaptations."
32I'm Bryan Lynn.
1Scientists say changes in the voice box of nonhuman primates over time may have led to human speech. 2The researchers said they examined the voice box, also known as the larynx, in 43 different species of primates. Their study showed that humans differ from apes and monkeys because humans lack a structure called a vocal membrane. This contains small, muscular attachments to the vocal cords. 3The researchers said humans also lack balloon-like structures called air sacs that may help some apes and monkeys produce loud, deep calls. The air sacs also help the primates avoid hyperventilating, which means to breathe an unusually fast rate. 4The scientists said the loss of these tissues resulted in a stable vocal system in humans that was critical to the development, or evolution, of human speech. Such speech permits humans to express thoughts and feelings using clear and complex sounds, the team said. 5Humans are primates, as are monkeys and apes. The evolutionary lineage that led to our species, Homo sapiens, split from the one that led to our closest living relatives, chimpanzees, about 6-7 million years ago. The researchers say the voice box changes are believed to have happened after that. 6Takeshi Nishimura is with Kyoto University's Center for the Evolutionary Origins of Human Behavior in Japan. He was a lead writer of the study, which recently appeared in the publication Science. Nishimura said the research suggested that complex vocal structures in nonhuman primates can make it difficult to effectively control vibrations. 7Another lead researcher, Tecumseh Fitch of Austria's University of Vienna, added that vocal membranes permit other primates to make louder, higher calls than humans. "But they make voice breaks and noisy vocal irregularity more common," he said. 8The larynx is a tube in the throat that is connected to the top of the windpipe and contains the vocal cords. It is used for talking, breathing and swallowing. "The larynx is the organ of voice, which creates the signal we use to sing and speak," Fitch said. 9Only living species were included in the study because these soft tissues are not likely to appear in fossils, the remains of ancient life. This means that it is unclear exactly when the changes took place. 10Fitch said it is possible the simplified development happened in a human ancestor called Australopithecus, which combined ape-like and human-like elements. Scientists believe Australopithecus first appeared in Africa about 3.85 million years ago. 11The research team said the changes could have happened later in our ancestor grouping Homo, which first appeared in Africa 2.4 million years ago. Homo sapiens - the primate species human beings belong to - appeared more than 300,000 years ago in Africa. 12Fitch noted, however, that while the evolutionary simplification of the larynx was important, it "did not give us speech by itself." He noted that other body developments also mattered for speech over time, including a change in the position of the larynx. 13"Speech and language are critically related, but not synonymous," said Harold Gouzoules. He is a primatologist and psychologist at Emory University in Atlanta, Georgia. "Speech is the audible sound-based manner of language expression - and humans, alone among the primates, can produce it," he wrote in a related commentary in Science. 14The researchers noted that the increased complexity of human spoken language came as a result of evolutionary simplification. 15"I think it's pretty interesting that sometimes in evolution 'less is more,'" Fitch said. He added, "By losing a trait, you might open the door to some new adaptations." 16I'm Bryan Lynn. 17Reuters reported this story. Bryan Lynn adapted the report for VOA Learning English. 18_____________________________________________________________ 19Words in This Story 20primate - n. a member of the group of animals that includes monkeys and people 21vocal cord - n. folds of skin at the top of your throat that make sounds when air from your lungs moves over them 22stable - adj. not likely to change or end suddenly 23vibration - n. to shake with small, quick movements 24fossil - n. part of an animal or plant that lived a long time ago that has been preserved in rock 25synonymous - adj. closely related or connected to something else 26audible - adj. able to be heard 27adaptation - n. the process or act of changing something to fit a new situation 28__________________________________________________________________ 29What do you think of this story? We want to hear from you. We have a new comment system. Here is how it works: 30Each time you return to comment on the Learning English site, you can use your account and see your comments and replies to them. Our comment policy is here.