Yawn next to your dog, and she may do the same. This is quite remarkable: Only a few animals exhibit such contagious behavior, and only dogs cross the species barrier. Now a study finds that dogs yawn even when they merely hear the sound of humans yawning; this constitutes the strongest evidence yet that canines may be able to empathize with us.
Besides people and dogs, contagious yawning has been observed in gelada baboons, stump-tail macaques and chimpanzees. Humans tend to yawn more with friends and acquaintances, suggesting that “catching” someone’s yawn may be tied to feelings of empathy. Similarly, some studies have found that dogs tend to yawn more after watching familiar people yawning. But it is unclear whether the canine behavior is linked to empathy. One clue might be if even the mere sound of a human yawn elicited yawning in dogs.
To explore that prospect, scientists at the University of Porto in Portugal recruited 29 dogs, all of whom had lived with their owners for at least six months. To reduce anxiety, the study was performed in familiar rooms in the dogs’ homes and in the presence of a known person but with no visual contact with their owners.
The team, led by behavioral biologist Karine Silva, recorded yawning sounds of the dogs’ owners and of an unfamiliar woman, as well as a control sound consisting of a computer-reversed yawn. Each dog heard all of the sounds in two sessions carried out seven days apart. During the sessions, the researchers measured the number of elicited yawns in dogs in response to sounds from known and unknown people.
As the team will report in the July issue of Animal Cognition, 12 of the 29 dogs yawned during the experiment. On average, canines yawned five times more often when they heard humans they knew yawning as opposed to control sounds. “These results suggest that dogs have the capacity to empathize with humans,” says Silva.
That’s not surprising, she says. People began domesticating dogs at least 15,000 years ago, and since then humans have bred them to perform increasingly complex tasks, from hunting to guiding the blind. This close relationship may have fostered cross-species empathy over the millennia.
“This study tells us something new about the mechanisms underlying contagious yawning in dogs,” says Evan McLean, a doctoral student at Duke University’s Canine Cognition Center, who was not part of the study. “As in humans, dogs can catch this behavior using their ears alone.” Still, he notes, the experiments don’t tell us much about the nature of empathy in dogs. “Do they think about our emotions and internal states the way we do as humans?”
Adam Miklosi, who practices ethology — the study of the behavior patterns of animals — in Budapest, agrees. “Using behaviors as indicators will only show some similarity in behavior,” he says, “but it will never tell us whether canine empathy, whatever this is, matches human empathy.” Previous work has shown, for example, that when dogs look guilty, they may not actually be feeling guilty.
“Dogs can simulate very well different forms of social interest that could mislead people to think they are controlled by the same mental processes,” says Miklosi, “but they may not always understand the complexity of human behavior.”
This article was produced by ScienceNOW, the daily online news service of the journal Science.