We've all heard that a dog's bark can be worse than its bite, but what about its yawn?
It turns out that aspect of canine behavior may provide evidence that dogs really are man's best friend. A study out of Lund University in Sweden found that our canine companions often yawn in reaction to seeing a human do the same thing.
The phenomenon, known as contagious yawning, is prominent among many groups of animals, humans included. However, the process, which is believed to indicate empathy and help contribute to group mentality and social structure, has been less studied between species.
Elainie Madsen, a doctor of psychology at Lund University who co-authored the study, told ABC News dogs were chosen because "they spend so much time with us, and we spend so much time with them."
"For those of us who have dogs," she said, "we often feel this very close connection with them, and we feel that they must understand or sympathize with our emotions and our emotional states."
The study took 35 dogs between the ages of 4 and 14 months and exposed them to various yawning human beings. Madsen found the results fascinating.
"We showed that the dogs were yawning contagiously - not just yawning but they also took on the emotion that yawning usually signifies, which is usually sleepiness and tiredness," she said.
As with humans, age proved to be a significant factor in whether or not a dog exhibited contagious yawning.
"They go through what seems to be an empathy development that somehow mirrors humans' empathy development, so it's just obviously on a very different time scale," Madsen said. "Human children don't begin to yawn contagiously until they're about 4 years old. Below that age, they seem pretty immune to others yawning at them. In dogs, this happens when they're about 7 months old. Dogs below that age don't seem to yawn, either."
So what does this mean for dog owners?
According to Madsen, it's a reason to rest assured that your dog really does love you as much as you love it.
"Dogs really have a close emotional connection with people," she said, "with owners as well as with other people."