When we think of the sounds that the chimpanzees comes to mind succession of cries, grunts and gasps which may reveal the animal’s arousal state, but nothing else. However, a new article published in the journal Communications Biology suggests that these may not just be confusing sounds, but rather the succession of these noises in a certain order can have a certain meaning.
The results obtained by Cedric Girard-Buttoz and his team led them to conclude that chimpanzees combine vocal calls in ordered sequences and to speculate that combining vocal sequences could potentially convey a range of meanings considerably wider than is possible with individual calls alone.
For the study, the authors analyzed 4,862 vocalizations produced by 46 chimpanzees wild adults from Taï National Park, Ivory Coast. They identified 12 different vocalizations, including growls, screams, roars and “hoos”, which the chimpanzees combined into a total of 390 unique vocal sequences.
The researchers found that the vocal sequences were organized according to a hierarchical structure, in which the individual units were integrated into sequences of two units, which in turn were integrated into sequences of three units. A) Yes, a vocal sequence may consist of a scream, followed by a growl, a roar, and another scream.
A code in chimpanzees?
The authors constructed networks of vocal sequences to examine whether individual vocalizations were combined randomly or in predictable orders. identified combinations of individual vocalizations that tended to occur together in two-unit sequences, as well as vocalizations that consistently occurred in the same order in two-unit sequences and could recombine into three-unit sequences.
For example, a gasping “hoo” reliably occurred in the first position of a two-unit sequence and was 12 times more likely to be followed by a gasping cry than you might expect. if the vocalizations were randomly combined. A panting “hoo” followed by a panting cry was more likely to be preceded by a non-gasping “hoo” than any other vocalization in a three-unit sequence.
The authors suggest that the apparent rules they observed in chimpanzee vocalization order provide the structural complexity needed to generate new meanings, although further research is needed to determine what meanings may be encoded by different sequences.
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Reference article: https://www.vozpopuli.com/next/chimpanzee-language-grunts.html