Contagious yawning is a behavior shared by chimpanzees, baboons, dogs and humans, and researchers said Wednesday that wolves can do it too, suggesting that empathy among animals is a common trait.
The research in the journal PLOS ONE focused on a pack of 12 captive wolves at the Tama Zoological Park in Tokyo, Japan.
Scientists observed the wolves' behavior for 254 hours over the course of five months, watching to see what happened when one of the wolves yawned and others were nearby.
"Yawning occurred significantly more often when the subjects were exposed to" the yawn of another in the pack, the study said.
"Wolves' susceptibility to yawn contagiously was affected by the strength of the social bond with the initial yawner, with wolves yawning more frequently to close social partners' yawns than to other individuals' yawns."
Even though the study involved a small number of wolves, researchers said the findings offer initial evidence that contagious yawning is linked to wolves' capacity for empathy.
Perhaps empathy is present in more species than previously thought, said lead author Teresa Romero, a researcher from The University of Tokyo.
"In wolves, as well as in primates and dogs, yawning is contagious between individuals, especially those that are close associates," she said.
"These results suggest that contagious yawning is a common ancestral trait shared by other mammals and that such ability reveals an emotional connection between individuals."