press trust of india
WASHINGTON, 7 JUNE: Scientists have found remarkable similarities in the way a human infant, a baby chimpanzee and a baby bonobo use gestures to communicate. Psychologists, who analysed video footage of a female chimpanzee, a female bonobo and a female human infant in a study to compare different types of gestures at comparable stages of communicative development, found remarkable similarities among the three species.
“The similarity in the form and function of the gestures in a human infant, a baby chimpanzee and a baby bonobo was remarkable,” said Prof Patricia Greenfield, a distinguished teacher of Psychology at the University of California, Los Angeles and co-author of the study. Gestures made by all three species included reaching, pointing with fingers or the head, and raising the arms to ask to be picked up. The researchers called “striking” the finding that the gestures of all three species were “predominantly communicative,” Prof Greenfield said.
To be classified as communicative, a gesture had to include eye contact with the conversational partner, be accompanied by vocalisation (non-speech sounds) or include a visible behavioural effort to elicit a response.
The same standard was used for all three species. For all three, gestures were usually accompanied by one or more behavioural signs of an intention to communicate. The apes included in the study were named Panpanzee, a female chimpanzee (Pan troglodytes), and Panbanisha, a female bonobo (Pan paniscus). They were raised together at the Language Research Center in Atlanta, which is co-directed by Sue Savage-Rumbaugh, a co-author of the study. There, the apes learned to communicate with caregivers using gestures, vocalisations and visual symbols (mainly geometric shapes) called lexigrams.
“Lexigrams were learned, as human language is, during meaningful social interactions, not from behavioural training,” said the study&’s lead author, Kristen Gillespie-Lynch.
The findings support the “gestures first” theory of the evolution of language. During the first half of the study, communicating with gestures was dominant in all three species.