Sukari the gorilla can growl. She can hum. She can complain. Now, scientists report, the gorilla has a new way of expressing itself. Sukari can “sniff”.
She and other zoo gorillas make the noise, a cross between a sneeze and a cough, when zookeepers with food are nearby. The unusual expression, which has not been observed in the wild and has never before been described in this species, may help gorillas grab people’s attention, says primatologist Roberta Salmi of the University of Georgia in Athens. The snough adds to the small but growing pile of evidence that captive apes can produce new vocal soundsSalmi and his colleagues report August 10 in PLUS ONE.
Salmi first encountered the snough years ago at Zoo Atlanta, when she and a zookeeper noticed gorillas making a strange sound. “We actually laughed,” she remembers. Gorillas make a variety of calls, but the snough stood out. As the animals pant, they open their mouths wide, almost as if preparing to sing. “It’s very theatrical,” says Salmi. And it seemed to come up only in one specific situation: when keepers showed up with food.
Salmi and her colleagues wondered if the animals would also snort at other times. So they videotaped eight western lowland gorillas at Zoo Atlanta in three different scenarios: when a bucket of fresh grapes, a keeper or a keeper holding the grapes sat outside the enclosure. The gorillas sniffed more when both the keeper and the food sat nearby, the team found. And they made other noises that can draw human attention, such as clapping, chest pounding, or room pounding. When the gorillas saw only grapes or only the keeper, they were mostly silent.
“That’s pretty decent evidence of the animals’ intention to ask the keeper for something,” says Zanna Clay, a primatologist at Durham University in England who was not involved in the work.
And snoughing wasn’t limited to the gorillas at Zoo Atlanta. Surveys of 19 zoos in the United States and Canada revealed that other gorillas make the same snorting sound. Those animals probably didn’t learn to sniff from the gorillas at Zoo Atlanta, because they’ve never been exposed to each other, says Salmi.
At this point, her team can only speculate how the cough originated, though she notes that a sneezing cough might work particularly well to get the caregiver’s attention. “Coughing and sneezing are signs of a cold, which are signs that caregivers pay specific attention to,” she says.
If gorillas want something they can’t physically reach, they may be “trying to use communicative cues to manipulate humans” to help, says Jared Taglialatela, an evolutionary biologist at Kennesaw State University in Georgia who was not involved in the study.
To date, most research on great ape vocal repertoires has been limited to the charismatic cousins of gorillas. Captive chimpanzees can blow “raspberries” and orangutans can whistle, but gorilla calls are not as well studied. “There is a small gap in our understanding,” says Taglialatela. If chimpanzees, orangutans and now gorillas can create novel vocalizations, an ability present in humans but rare in the animal kingdom, it’s possible that the ancestor of these animals and humans did too, she says.
Clay thinks that studying gorillas could offer new clues about what drives language development. A snort isn’t the same as talking, he points out, but it could be a sign that there’s more to gorillas than meets the eye.