New Delhi: Acoustics of chimpanzees’ laughs, grunts and whimpers have revealed that young ones may go on to develop distinct vocal patterns or ‘dialects’, according to a study.
Researchers said findings published in the journal PLOS One provide a new way of understanding how distinct vocal patterns between varied populations of chimps originated and developed, and challenge the assumption that calls of the primate are inflexible and determined solely by genetics.
They compared the vocalisations of infant and juvenile chimpanzees from two geographically separated populations at Chimfunshi Wildlife Orphanage in Zambia and Gombe National Park in Tanzania.
The authors “found that we could discriminate between sites for all call types, indicating the presence of dialects across the chimpanzee vocal repertoire”.
They also discovered that differences between the groups became more pronounced as the animals grew older, suggesting that vocal behaviour continues to develop throughout early life.
“Understanding how communication develops during early life is fundamental to understanding animal behaviour. Our findings show that chimpanzee vocalisations are not simply fixed from birth but continue to develop as young animals interact with their social and ecological environments,” lead researcher Kassandra Giragosian, a doctoral researcher at Queen Mary University of London, said.
Early in the human evolution, acoustics of vocal behaviour is largely similar across populations. However, as evolution progressed, acoustic differences between populations grew bigger, the researchers said.
Similar to humans, who develop accents specific to a region, the team found that young chimpanzees from different communities produced subtly different vocal patterns too.
Further, population-specific vocal characteristics were found to be already present in infancy, while others emerged during the juvenile years.
The developmental pattern suggested that social interactions, environmental conditions and other non-genetic influences may all contribute to shaping how young chimpanzees communicate, the researchers said.
The study provides the first evidence that chimps develop population-specific, distinct vocal differences or dialects as they develop, and contributes to a growing body of evidence that primate communication is more flexible and dynamic than previously recognised, they said.
The research also offers a new perspective on the processes that shape vocal behaviour in other species as it focussed on how communication changed with time, instead of comparing adults from different populations.
The researchers also provide a framework for investigating how communication systems emerge and diversify within animal populations, they said.