The secret language of chimpanzees

When we think about the sounds that the chimpanzees comes to our mind succession of screeches, grunts, and gasps that can reveal the state of the animal’s arousal, but little else. However, a new paper published in the magazine Communications Biology suggests that perhaps these are not just jumbled sounds, but rather the succession of these noises in a certain order may have some kind of meaning.

The results obtained by Cedric Girard-Buttoz and his team lead them to conclude that chimpanzees combine vocal calls in ordered sequences and speculate that the combination of 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”, that the chimpanzees combined into a total of 390 unique vocal sequences.

The researchers found that the vocal sequences were organized in a hierarchical structure, in which the individual units were embedded in sequences of two units, which in turn were embedded in sequences of three units. A) Yes, a vocal sequence might consist of a scream, followed by a growl, a roar, and another scream.

A code among 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 within two-unit sequences, as well as vocalizations that consistently occurred in the same order within 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 would be expected if the vocalizations were randomly combined. A gasping “hoo” followed by a gasping cry was more likely to be preceded by a non-gasping “hoo” than any other vocalization within a three-unit sequence.

The authors suggest that the apparent rules they observed in the order of chimpanzee vocalizations offer the structural complexity required to generate new meanings, although more research is needed to investigate what meanings may be encoded by different sequences.

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Reference article: https://www.vozpopuli.com/next/chimpanzee-language-grunts.html