Captive chimpanzees use specific vocalizations to communicate with humans according to new research published in the current issue of the journal Animal Behaviour. The researchers, lead by Dr. William Hopkins of Yerkes National Primate Research Center at Emory University, say these sounds are not used in other contexts -- only to elicit attention from humans. The researchers say the findings may help explain the evolution of language in primates.
Studying chimp behavior at the Yerkes National Primate Research Center the researchers found that chimps commonly produce a vocal signal, dubbed the ‘raspberry’ or 'Bronx cheer', to function as an attention-getting device. The researchers compare the vocal signal to tool use among great apes.
"Wild and captive chimpanzees are well known for their tool-using abilities... Within this framework, the chimpanzees have a goal, to obtain a food item that they cannot otherwise attain. In this context, the chimpanzees use their communicative behaviours to manipulate a human (the tool) to attain a food item (goal)," write the researchers. "Moreover, their communicative behaviour is flexible in this context because the chimpanzees alter the modality of their communicative signals in accordance with the attentional state of the human. Specifically, when a human is facing them, they are more likely to use visual signals such as manual gestures, but when a human is facing away from them, they are more likely to use auditory signals, including vocalizations... Thus, both chimpanzees and humans can tactically deploy their communicative signals towards immediate ends, presumably using homologous problem-solving capacities."
The researchers say the findings may be significant in furthering the understand of the language evolutionin that chimps generate "novel communicative signals" depending on their circumstances.
"What may distinguish the great apes from other anthropoids is the motivation for this creative or generative signal development. Chimpanzee signals lack the recursive qualities that truly set human languages apart, nevertheless, as far as we know, few other primates invent as wide a range of signals in such diverse modalities as do chimpanzees... the capacity not merely to discriminate but to generate novel communicative signals, which is a hallmark of human linguistic communication, may have relatively ancient roots in the signalling characteristics of our ape ancestors."