Waa huu! Chimps combine calls to communicate new meaning

Chimpanzees emit “huu” calls when they are afraid or surprised and “waa” barks when recruiting other chimps Keystone / Hugh Kinsella Cunningham

Like humans, chimpanzees communicate in sentences. They link individual calls in certain situations to create a new meaning, according to scientists at the University of Zurich (UZH).

“Language is considered a distinguishing feature between humans and animals. The fact that animals are also able to speak in sentences turns this notion on its head,” said lead author Maël Leroux.

To study the apes’ language, the researchers placed a stuffed python in the path of wild chimpanzees in Uganda. They used a thin thread to move the snake as soon as a chimpanzee approached. The resultsExternal link were published on Thursday in the journal Nature Communications.

It was known that chimpanzees emit “huu” calls when they are afraid or surprised and “waa” barks when recruiting other chimps, for example when hunting or fighting. When the apes were surprised by the snake, they combined the two calls.

“While the individual calls are used in a variety of situations, the combination of ‘huu’ and ‘waa’ is used in a very specific context,” Leroux said.

Greater urgency

In addition, the scientists found that more apes rushed to help after hearing a combination of the two calls. Further experiments with sound recordings of the calls confirmed this. When the researchers played recordings of individual calls to the chimpanzees, the reactions were significantly weaker than when the calls were combined.

“So the chimpanzees seem to get more information from a combination of calls than from individual calls,” Leroux said. This indicates that they derive meaning from the sentence and understand its meaning, he concluded.