Like a case of chickenpox or an ice bucket challenge, a yawn can be pretty contagious. Humans have caught yawns by looking at each other, seeing pictures of people in the midst of yawning and even by thinking about yawning long enough. Research also points to chimpanzees, bonobos and dogs as other species who catch yawns. And a recent report in the journal PLOS One adds wolves to the list, too.
"In wolves, as well as in primates and dogs, yawning is contagious between individuals, especially those that are close associates," says Teresa Romero, a behavioral and cognitive scientist at the University of Tokyo, in a statement.
In a study of 12 gray wolves at Tama Zoological Park in Tokyo, Japan, Romero and her colleagues observed the animals' actions over a period of five months. (None of the wolves showed signs of stereotypic behavior that affect captive species, the authors write; the researchers did not address impacts captivity had on this research, however, beyond calling for future studies in wild populations.) An individual wolf was much more likely to yawn if he or she had spotted another wolf yawning, the scientists report.