Unlike our primate cousins, humans change voices to communicate with babies. — AFP
Talking to babies in a high-pitched voice and using exaggerated pronunciation seems natural to most parents. This way of speaking, found in all human cultures, is thought to facilitate language learning in young children. But is this universal human practice shared by our closest cousins?
A study published in the journal Science Advances reveals that great apes communicate very little with their young, suggesting that our propensity for "baby talk” is a distinctive feature of the human species.
Previous research has shown that this "baby talk” promotes vocabulary and language skills, but its evolutionary origins remained a mystery.
To find out more, a team of biologists and linguists from the University of Zurich and the University of Neuchatel teamed up with colleagues from France, Germany and the United States.
Together, they studied five species of great apes (humans, bonobos, chimpanzees, gorillas and orangutans) to observe how they communicate with their young in their natural environment.
They found that humans stand out significantly for their use of "baby talk,” unlike their primate cousins. "We were surprised by how little of this type of communication we actually observed in our closest living relatives," explains Franziska Wegdell, one of the three first authors of the study, quoted in a news release.
Vocal and gestures
This raises the question: how do the young of these great ape species learn to communicate?
Researchers believe that the answer lies in indirect listening. In humans, infants acquire new words simply by listening to conversations around them.
The team therefore compared this "infant-surrounding communication” in the five species studied and found that all infants are exposed to it in a similar way, except for orangutans.
It may therefore be that, like humans, great apes acquire certain aspects of their communication system socially, but by relying on communication in the surrounding environment rather than direct exchanges.
This study nevertheless has limitations. The researchers focused solely on vocal communication, whereas great apes also communicate with their young through gestures.
"We know that non-human great apes direct gestures at their infants, and that some of these gestures even exhibit features also found in human infant-directed communication," says study co-first author, Caroline Fryns, of the University of Neuchatel.
Understanding the evolution of language requires studying our closest living relatives, because language does not remain static over time.
This study reveals that "baby talk” has developed particularly in humans, even though other species – monkeys, bats, cats and dolphins – also communicate directly with their young. This unique feature could partly explain why humans excel in the art of speech. – dpa
