The study of language development in non-human primates, notably chimps, has long been a topic of interest for understanding the evolutionary roots of human language. Chimpanzees are one of our closest living relatives, sharing 98.7% of our DNA.
A study found that juvenile chimps are capable of vocal functional flexibility, a known building block in human language development. The ability to make sounds that can serve a range of tasks is crucial to how we learn to speak, but it has long been assumed that non-human primates do not share this ability.
Human newborns produce noises for certain reasons. Screams, chuckles, and cries, for example, each have a specific purpose and convey a distinct feeling. However, some free speech sounds, such as pre-babbling, are more adaptable in their function. According to new research, infant and juvenile chimps have similar vocal flexibility, implying that the foundations for speaking are based in our primate evolutionary background.
These findings add to a growing body of material contradicting conventional assumptions about monkey voice output and highlight the importance of additional comparative developmental investigations to improve our knowledge of the evolutionary origins of language.
Marina Davila-Ross
Dr. Derry Taylor of the University of Portsmouth’s Department of Psychology, the study’s lead author, stated, “All living things communicate, but only humans communicate using language.” Science has yet to uncover the puzzle of how this happened.
“Until now we didn’t have evidence of vocal functional flexibility in non-human primates early on. This discovery holds profound implications for our understanding of the origins of human language.”
The paper, published in iScience, is one of the first systematic studies of early chimp vocal production and function. A team from the University of Portsmouth in England, the University of Neuchâtel in Switzerland, and Université Clermont Auvergne in France, filmed 768 vocalisations in 28 young chimpanzees at a sanctuary in Zambia. These included grunts, whimpers, laughter, screams, hoos, barks, squeaks, and pant hoots.
When scientists reviewed and classified the sounds, they discovered that the chimps, like human newborns, generated calls with diverse affective states – happy, neutral, or negative – as well as a variety of facial expressions and motions.
These dynamically articulated call types, particularly grunts, elicited different responses from social partners depending on how they were combined with specific behaviors. The findings revealed a significant similarity with previous human newborn study.
Co-author Marina Davila-Ross, Associate Professor in Comparative Psychology at the University of Portsmouth, said: “Many studies comparing apes with human children have tested them at different ages in order to discuss differences in language development between both species.
“We mirrored another piece of research carried out in America, which looked at vocal functional flexibility in human infants, to ensure that our research followed a similar methodology and the results could easily be compared. These findings add to a growing body of material contradicting conventional assumptions about monkey voice output and highlight the importance of additional comparative developmental investigations to improve our knowledge of the evolutionary origins of language.”
