A new study published in the journal Scientific Reports provides evidence that sun bears (Helarctos malayanus), a typically solitary species, have the ability to mimic the expressions of their conspecifics and that they do so by matching the exact facial variants they interact with. It is the first time exact facial mimicry has been seen outside of humans and gorillas.
The sun bear (Helarctos malayanus) at Alma Park Zoo, Brisbane, Australia. Image credit: Andrew Napier / CC BY 2.0.
Facial mimicry is when an animal responds to another’s facial expression with the same or similar expression.
“Mimicking the facial expressions of others in exact ways is one of the pillars of human communication. Other primates and dogs are known to mimic each other, but only great apes and humans, and now sun bears, were previously known to show such complexity in their facial mimicry,” said Dr. Marina Davila-Ross, a researcher at the University of Portsmouth.
Dr. Davila-Ross and her colleagues studied sun bears for more than two years.
They found bears can use facial expressions to communicate with others in a similar way to humans and apes, strongly suggesting other mammals might also be masters of this complex social skill and, in addition, have a degree of social sensitivity.
“Because sun bears appear to have facial communication of such complexity and because they have no special evolutionary link to humans like monkeys are apes, nor are they domesticated animals like dogs, we are confident that this more advanced form of mimicry is present in various other species. This, however, needs to be further investigated,” Dr. Davila-Ross said.
“What’s most surprising is the sun bear is not a social animal. In the wild, it’s a relatively solitary animal, so this suggests the ability to communicate via complex facial expressions could be a pervasive trait in mammals, allowing them to navigate their societies.”
The scientists coded the facial expressions of 22 sun bears (aged 2-12) in spontaneous social play sessions.
The animals were housed in Bornean Sun Bear Conservation Centre in Malaysia in which enclosures were large enough to allow bears to choose whether to interact or not.
Despite the bears’ preference in the wild for a solitary life, the bears in this study took part in hundreds of play bouts, with more than twice as many gentle play sessions compared to rough play.
During these encounters, the team coded two distinct expressions — one involving a display of the upper incisor teeth, and one without.
The bears were most likely to show precise facial mimicry during gentle play.
“Such subtle mimicking could be to help two bears signal that they are ready to play more roughly, or to strengthen social bonds,” explained first author Derry Taylor, a PhD candidate at the University of Portsmouth.
“It is widely believed that we only find complex forms of communication in species with complex social systems. As sun bears are a largely solitary species, our study of their facial communication questions this belief, because it shows a complex form of facial communication that until now was known only in more social species.”
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Derry Taylor et al. Facial Complexity in Sun Bears: Exact Facial Mimicry and Social Sensitivity. Scientific Reports 9, article number: 4961; doi: 10.1038/s41598-019-39932-6
