June 14, 2024

New Research Suggests Chimpanzees and Humans Share Similarities in Language Development

A recent study has provided compelling evidence that young chimpanzees possess vocal functional flexibility, a key building block in the development of human language skills.

The ability to produce sounds with multiple functions is crucial to the acquisition of speech in humans. However, it has long been believed that this skill is unique to humans, and not shared by non-human primates.

When human babies vocalize, their sounds serve distinct purposes. For instance, screams, laughter, and cries are all tightly linked to specific emotions and intentions. On the other hand, pre-babbling sounds are more flexible in their function.

New research has discovered that infant and juvenile chimpanzees display similar vocal flexibility, indicating that the foundations for language are deeply rooted in our primate evolutionary heritage.

Dr. Derry Taylor, the lead author from the University of Portsmouth’s Department of Psychology, stated, “All living beings communicate, but only humans communicate using language. How this ability emerged remains a mystery within the scientific community. Until now, we didn’t have any evidence of vocal functional flexibility in non-human primates at an early age. This discovery has profound implications for our understanding of the origins of human language.”

The study, published in iScience, is one of the first systematic examinations of early chimpanzee vocal production and function. Researchers from the University of Portsmouth (England), the University of Neuchâtel (Switzerland), and Université Clermont Auvergne (France) recorded 768 vocalizations from 28 young chimpanzees at a sanctuary in Zambia. These vocalizations included grunts, whimpers, laughter, screams, hoos, barks, squeaks, and pant hoots.

Upon reviewing and categorizing the sounds, the researchers noticed that, similar to human infants, the chimpanzees produced calls with varying affective states—positive, neutral, or negative—accompanied by a range of facial expressions and body movements.

The flexible expression of these call types, particularly grunts, also elicited different responses from their social partners depending on how they were expressed. These findings highlight a clear parallel with existing research on human infants.

Co-author Marina Davila-Ross, Associate Professor in Comparative Psychology at the University of Portsmouth, explained, “Many studies that compare apes with human children have tested them at different ages to uncover differences in language development between the two species. We modeled our research after a study conducted in the United States, which examined vocal functional flexibility in human infants. This enabled us to adopt a comparable methodology, facilitating a meaningful comparison of results.”

These findings contribute to a growing body of evidence challenging traditional beliefs about primate vocal production and underscore the importance of conducting further comparative developmental studies to deepen our understanding of the evolutionary origins of language.

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