Scientists have known for decades that yawns are infectious among people, so much so that simply reading or thinking about them can trigger a chain reaction of gaping mouths in what they call "contagious yawning".
Yawns can spread in a similar way among chimpanzees and macaques too, though not among people with autism, and is thought to be linked with empathy and the ability to read the thoughts of another individual.
Now the first ever study to report that human yawns induce yawning in dogs is published today in the journal Biology Letters by a team led by Dr Atsushi Senju of Birkbeck College, University of London.
They presented 29 dogs with yawning humans and also with a control movement, where people just opened their mouths.
Even though a wide variety of breed was represented, such as Dobermans, Yorkshire Terriers, Dachshund, Spaniels, Labradors and more besides, they found that 21 of the dogs yawned in response, showing that "dogs possess the capacity for a rudimentary form of empathy."
This supports recent research, said Dr Senju. "Other studies also demonstrated that dogs follow human pointing, more likely to tell humans the location of hidden objects when they didn't see the object being hidden, and tend to steal food when the humans are looking away or closing their eyes."The reason that dog and man are best friends is that they were domesticated 15,000 or more years ago when our ancestors started to produce more food than they could consume and befriended wolves, probably animals that liked to spend time in human company.
Fido's great-great-grandmother was a grey wolf who took more interest in humans than her peers did. Subsequent selection of those dogs that were more communicative and aware of human emotions probably helped them to be so empathic.
"As the dog's amazing skills to read human communication cues are thought to have been selected by human over last 15,000 years, it is also possible that the same evolutionary process affected their skills to empathise with humans," he said.
But he said more work must be done to prove this conjecture. "Another possibility is that contagious yawning (and possibly empathy) could be a more widespread characteristics among mammals."
The former explanation, that they are empathic, would back other work that shows that ill and elderly people do better with pets. "It is possible that such contagion coordinate the mood status between the dogs and humans. We may even feel like that "(my) dog understand my feelings" based on their contagious behaviour."
But surprisingly little is known about the mechanisms underlying this common expression of tedium, with some arguing it is a mere reflex and others that it shows we empathise with another person.
The yawn is primal, being present in a vast range of creatures: mammals and most other animals with backbones yawn as well as fish, turtles, crocodiles and birds. But the fundamental reason we yawn remains mysterious.
It does not always mean an individual is tired - it could help increase the state of alertness, may help keep the brain cool and is linked with being nervous too.Found this Post interesting? Discover more Curious Reads.