Yawning can be contagious – just ask your dog.
It’s two in the afternoon. You’re sitting in a meeting room listening to a presentation that is proving to be about as interesting as reading the instruction manual of a toaster. Your eye-lids are doing battle with gravity, and your head threatens to loll forward, but you figure you’ll probably make it through the meeting, so long as you find something else to distract yourself.
But glancing around the room, your efforts are suddenly thwarted. You see your colleague noticeably stifling a yawn. In your post-lunch under-caffeinated state you are defenceless – a yawn is soon welling up within you and there’s little you can do to stop it.
Infectious yawning is a curious phenomenon.
Simply seeing, or even hearing, another person yawn is enough to trigger 45–60% of adults to yawn in response. Contagious yawning isn’t just a human quirk – chimpanzees, bonobos, baboons, budgerigars and our humble domestic companion, the dog, also succumb to the contagion.
So, why is yawning contagious?
In humans, recent theories have suggested that contagious yawning is an indicator of empathy. When we yawn in response to someone else’s yawn, we are communicating that we empathise with them. Being the social creatures that we are, empathy is an important social emotion that can strengthen the bonds between people.
The theory is not without evidence. Brain imaging studies have revealed that neural networks associated with empathy and social skills are activated during contagious yawning. And the more empathic you are, the more susceptible you are to contagious yawning.
But what about when a dog yawns after seeing a human yawn? Is the dog being empathic, or is there some other explanation?
To investigate why dogs suffer from contagious yawning, a team of researchers from the University of Tokyo and the Japan Society for the Promotion of Sciences filmed more than 8 hours of footage of humans trying to make dogs yawn.
Twenty-five dogs – from Siberian huskies and Labradors to Chihuahuas, Pekingese and mixed breeds – were involved in the study, which involved placing them in four different experimental situations.
The dogs were tested for their response to a person –the dog’s owner or a researcher unfamiliar to the dog – either acting out an audible yawn, or simply stretching their arms while opening and closing their mouth as a ‘control’ movement.
For five minutes at a time, a person sat in front of a dog, repeatedly gained the dog’s attention by calling its name, then yawned or performed the ‘control’ movements. All resulting dog yawns were then tallied to see which circumstances produced the most contagious yawning in the pooches.
Thirteen of the dogs yawned during the experiment. Dogs were more likely to yawn when they observed their owner yawn than when they saw someone unfamiliar yawn. An emotional connection with the person yawning seemed to be increasing the dogs’ susceptibility to contagious yawning.
Contagious yawning was also more likely if a dog’s owner acted out a yawn, rather than simply opening and closing their mouth. There is no consensus among yawn researchers about what constitutes the perfect experimental control for a yawn, but the dogs seemed to be less affected by the control used in this study – they weren’t as interested if the yawn wasn’t a yawn.
The empathy argument for dogs was looking good. But just to be sure, the researchers also strapped a heart rate monitor to 21 of the dogs, to rule out the yawning being an anxiety response in the dogs, as has been hypothesised. The dogs’ heart rates remained essentially constant no matter which situation they were placed in, effectively ruling out stress as a potential cause of the yawning.
Domesticated dogs form special bonds with their owners, and are keenly attuned to their owners’ behaviours. While watching dogs yawn for more than 8 hours might seem, well, yawn-inducing, it does give us an insight into whether man’s best friend feels empathy towards us.
Apparently, they do. Not that any dog owner was in any doubt.
Reference: Romero T, Konno A & Hasegawa T. (2013). Familiarity bias and physiological responses in contagious yawning by dogs support link to empathy. PLoS ONE DOI: 10.1371/journal.pone.0071365