Captive Gorillas Have Developed A Special Profession To Communicate With Human Zoos

Gorillas may be capable of vocal learning and innovation

Gorillas may be capable of vocal learning and innovation. Image: Patrick Rolands/Shutterstock.com

“Love!” Apparently, that gorilla is talking about “tell me, old boy, chuck us a few grapes would you?”. What is particularly remarkable about this particular voice, however, is that it appears to have been developed by captive gorillas for the specific purpose of communicating with human zookeepers, and is never used in interaction with other gorillas. According to a new study, the invention of such a call shows that gorillas are able to learn voice and innovate, the smart sausages.

Previous research on other great apes has shown that both chimpanzees and orangutans encounter new sounds when they encounter new settings in captivity. For example, chimps have been known to blow raspberries at human handlers, while orangutans prefer to whistle.

In the new study published in PLOS ONE, the researchers devised an experiment to determine if this ability is shared by the western gorillas housed at the Atlanta Zoo. Six female and two male monkeys were observed in three experimental situations, the first of which placed the apes within a meter of a known zookeeper, the second of which involved a solitary bucket of grapes, and the third of which involved the zookeeper holding the bucket of food by him.

According to the study’s authors, “gorillas sang frequently during the human food condition, and the most frequently used vocal signal was a species-atypical sound somewhere between a sneeze and a cough… which we named the attention-demanding sound (AG) or ‘snough’.”

This call, which has never been described in the species vocal repertoire, was used by four of the eight gorillas involved in the study, and accounted for 85 percent of all vocalizations observed during the experiments. The researchers explain that the sound is acoustically different from all the other calls that gorillas usually produce during feeding, such as grunts or hums.

“In our study, captive gorillas never used the AG call when communicating with each other, supporting the idea that it is a novel sound that is not part of the typical gorilla-gorilla communication repertoire and that it emerged to address the communication need to attract people. human attention in captive settings,” the authors wrote.

Expanding their investigation, the researchers contacted handlers at other facilities across the US and Canada. They found confirmation that the same call is being used by 33 different gorillas housed in 11 different zoos. However, after examining video footage of 15 of these gorillas, the study authors observed only six “snoughing”, suggesting that about 40 percent of western gorillas may under forced to use the voice.

“The AG call is probably less common than the more prominent raspberry call used by captive chimpanzees, which may indicate that zoo gorillas only recently adopted this sound to get human attention,” they write. Furthermore, the fact that the call is often used by gorillas that are directly related to each other – such as siblings or parents and children – suggests that it may be passed on by social learning.

Previously, sounds like this “snough” were attributed to the famous but controversial “talking” gorilla Koko, who used a variety of novel sounds when interacting with human caregivers. “These included a fake cough/sneeze, which was accompanied by a hand gesture and open mouth and strongly resembled the AG sound of our study,” say the study authors.

“It is not yet known whether the AG (or snough) call has evolved randomly or whether it has been learned/modeled by observation, as seems to be the case with Koko’s fake cough and the orangutans’ whistle.”

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