The sun bear, already well-known online for its silly faces, is the first non-primate, non-domesticated animal found to mimic the facial expressions of its playmates. The new research adds complexity to our understanding of the ways animals communicate.
Sun bears are normally solitary animals, and are an elusive, difficult-to-study species. This new work from researchers in the United Kingdom, France, Germany, and Malaysia demonstrates evidence of a kind of social communication only seen previously in primates and domesticated animals.
“In the sun bear, we have an animal that, in the wild, has strong solitary tendencies, yet is showing social communication that outstrips other species in its complexity,” study first author Derry Taylor from the University of Portsmouth told Gizmodo.
The vulnerable sun bear lives in Southeast Asia and is threatened by habitat loss. The researchers chose them as a study subject mainly out of convenience, Taylor explained, as the Bornean Sun Bear Conservation Centre is located near an orangutan rehabilitation centre where the researchers also spend time. But they noticed that the bears would show a variety of facial expressions during play, just like the orangutans did, so they asked whether the bears were showing facial mimicry during their own play, too.
The team filmed 22 bears aged 2 to 12 years in the rehabilitation centre for two stints totalling two years. They captured 372 instances of play between the bears on film. They turned the video into data, noting whether the bears were facing one another and when during the play the bears showed one of two faces: the first, in which the bear’s upper lip and nose were raised, wrinkling its muzzle and exposing its upper teeth; and the second, in which the bear didn’t wrinkle its muzzle and show its teeth. It’s kind of like the difference between the face a human would make while yelling “ahh” versus just speaking “ah.”
An analysis of the data showed that the bears were more likely to make any open-mouth face if the other bear was also making an open-mouth face, according to the study published yesterday in Scientific Reports. They were also more likely to make open-mouth expressions if they were facing one another. And perhaps most importantly, the bears were more likely to make the teeth-bared, yelling-“ahh” face if the other bear did first, and were also more likely to make the teeth-not-bared, speaking-“ah” face if the other bear did first.
This kind of facial communication has only been observed before in domesticated dogs and some species of primates, said Taylor. “Complex communication is something more widespread than we typically think,” he said.
Two researchers Gizmodo spoke to were pleased with the results of the paper, and both praised the thorough work of the study’s lead author, Marina Davila-Ross, reader at the University of Portsmouth. “I think that the most important thing that she underlines is that the facial mimicry has been found in a solitary species,” Elisabetta Palagi, associate professor in the University of Pisa department of biology who was not involved with the study, told Gizmodo.
Palagi said the study highlights that though we normally consider how “social” a species is as underpinning its ability to communicate socially, what’s more important is instead the level of familiarity that the animals share when they interact with one another. She suggested a study paying further attention to the bonds among individuals‚ to examine whether facial mimicry changes between closely associated bears and less-closely associated bears.
Anne Burrows, a professor in health sciences at Duquesne University who studies biological anthropology, said it was “a really important piece of work” demonstrating social communication in a solitary and understudied species. Still, she questioned whether the team had unambiguously demonstrated exact facial mimicry, or whether these are just the facial expressions the bears make during play. She’d like to see the study further performed on the youngest possible bears when they’re only just learning to make these facial expressions.
Taylor told Gizmodo that he’d ultimately like to understand the purpose of these facial expressions and what they’re communicating. Perhaps they signal that it’s time for the bears to turn up the roughness dial on their play, for example.
Studying animals in this way gave Taylor a new perspective beyond just the study. “Once you spend some time, you realize that there are strong individual differences in the bears’ character,” he said. “The general process of getting to know one group over a long period of time is very insightful.”