Young chimpanzees have a vocal ability that is also seen in human babies—one that is considered to be a key building block in language development—a study has revealed.
The research, published in the journal iScience, has "profound implications" for our understanding of the mysterious origins of human language, indicating that it is rooted in our primate ancestry.
All living things communicate, but only humans communicate using language. How this came to be the case is a question that modern science has yet to resolve.
In an attempt to provide new insights into this mystery, a team of researchers decided to investigate vocal development in chimpanzees, one of our closest living relatives. Understanding chimp vocal development is essential to unraveling the evolutionary roots of human language, according to the study's authors.
"While we know a lot about adult chimpanzee vocal communication, we knew very little until recently about their vocal development," Derry Taylor, the study's lead author, told Newsweek.
"This is striking because within a human lifetime language acquisition is a developmental process. So we decided to look at early vocal development in chimpanzees and find out to what extent it mirrors early human vocal development," said Taylor, who works at the Department of Psychology at the U.K.'s University of Portsmouth.
In human development, the ability to communicate with language is directly built upon the early capacity of infants for "vocal functional flexibility." This is the ability to express the same vocalizations in different ways to fulfill a variety of functions or achieve different aims.
Human babies make noises that have specific functions. Screams, laughs and cries, for example, all have a rigid purpose and clear emotions attached to them. However, there are other sounds, such as pre-babbling, that are more flexible in their function.
Vocal functional flexibility is fundamental to how humans learn to speak, although it has long been believed that nonhuman primates, such as chimps, do not share this ability.
In the new paper, researchers provide evidence that challenges this view in one of the first systematic studies of early chimpanzee vocal production and function.
For their study, the team of scientists filmed 768 vocalizations in 28 young chimps living in a sanctuary in Zambia, Africa. The vocalizations included grunts, whimpers, laughter, screams, barks, squeaks and hoots.
They then reviewed and classified the sounds. They found that some of the vocalizations the chimps produced, particularly grunts, displayed evidence of vocal functional flexibility and were associated with different affective states—positive, neutral or negative.
"What we found was that the early chimpanzee vocal repertoire shows some interesting similarities with early human vocal behavior," Taylor said. "In particular, we found that, like human infants, the infant chimpanzees showed vocalizations like screams, cries and laughs, each communicating a specific emotion which mothers responded to in stereotyped ways."
He went on: "But most interestingly, we found their grunt vocalizations expressed a full range of emotional states, and mothers' responses were dependent on how grunts were expressed. This is something that is known to be characteristic of the direct developmental precursors to speech vocalizations in human infants and provides an indispensable foundation for language development."
For a long time, researchers have believed that primate vocalizations expressed simple emotional states with little flexibility in their function. But the latest study contributes to a growing body of evidence that challenges these conventional beliefs.
"Our findings undermine this long-held view and bring us closer to explaining why all living things communicate yet only humans communicate using language, because the essential foundations that language is built upon take root in our primate ancestry," Taylor said.
Uncommon Knowledge
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
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Aristos is a Newsweek science reporter with the London, U.K., bureau. He reports on science and health topics, including; animal, ... Read more
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