Hormones Show Dogs Don’t Just Think of Us As Providers of Food

When dogs and humans share long looks, a chemical involved in social bonding surges through their bodies

dog and owner
Big Cheese Photo/Corbis

When dog owners share long, seemingly soulful gazes with their canines, the thought might cross their minds: Do those quirked eyebrows, perked ears and tilted head mean their pets are trying to communicate a recipricol affection? Or are they just looking for a treat? 

Well, rejoice, dog lovers: scientists have come up with a quantifiable measure that indicates dogs aren’t just hoping for food, reports a study published in Science.

During your typical canine-human gaze session, we get a surge of oxytocin, the hormone associated with social bonding and a few other behaviors. Turns out the same hormone starts coursing through the doggy system as well. 

"It's really cool that there's actually some science to back this up now," Evan MacLean, an evolutionary anthropologist and co-director of Duke University's Canine Cognition Center, told NPR.

The shared oxytocin dosing may have arisen in both humans and dogs as the latter were domesticated, reports Arielle Duhaime-Ross for the Verge. She writes:

[Researchers] compared oxytocin levels in urine belonging to 30 dogs and their owners before and after a 30-minute interaction. They also measured how long dogs and owners stared at each other, and how often they touched. Then, they did the same things with pairs of wolves and their owners; the wolves has been raised by humans their entire lives. The idea here was to see if undomesticated animals that are closely related to dogs would lead to the same result.

The researchers found that the dogs and their owners had increased levels of oxytocin in their urine after gazing into each other’s eyes. This didn’t occur in the wolves, or the humans who own them, however. Moreover, the owners whose dogs looked at them the most experienced the largest increase in oxytocin — an increase that their dogs mirrored.

A second experiment involved a dab of the hormone on dogs’ noses. The artificially oxytocined female dogs gazed longer at their owners, and the owners subsequently felt the effects of an answering surge of their own oxytocin levels. Male dogs didn’t change their behavior, however. Since unfamiliar people were also in the room for this experiment, the researchers write that increased vigilance could have kept the male dogs from demonstrating the effects of the extra oxytocin.

However attractive the findings might be, there is a complication. Oxytocin isn’t only involved in loving behaviors, but also in aggression and feelings of isolation. That fact gives some researchers pause. "There is a fashion in science at the moment, to identify changes in hormone levels with changes in emotional and feeling states," Clive Wynne, a psychologist at Arizona State University who studies how dogs and people interact, told NPR.

But even if oxytocin is just part of the picture, dog owners didn’t really need science to tell them that their puppies feel affection toward them. "I think the best evidence that any dog lover has that their dog loves them is what the dog does was when it's around them," Wynne says. "We're entitled to trust the evidence of our own senses."

And, sorry, cat owners, it still appears that feline companions really don’t get what you mean by those social cues. No oxytocin feedback loop there.