Why is it that when a dog stares longingly into your eyes, you almost cannot help petting them and letting out a fond sigh? A new study shows that dogs may trick our biochemistry to get that effect. In a new study, researchers found that when you stare into a dogs puppy eyes eyes, your level of the hormone oxytocin goes up. Oxytocin (also known as the “love hormone”) is the hormone that contributes to feelings of happiness and bonding. Lead author, Miho Nagasawa of Azabu University and a team of researchers brought in 30 dogs and their owners, marking down all behaviors between the two for 30 minutes, such as touching, talking, and gazing. Afterward the team measured oxytocin levels in the owners’ urine and found that gazing into a dog’s puppy eyes out-shined all other actions in increasing oxytocin.
The interesting part of the study is that researchers measured the oxytocin levels of the dogs as well. They found that dogs have the same response to eye gazing, with oxytocin levels increased. The study suggests that there is a sort of feedback loop when you and a dog stare at each other: oxytocin levels increase in both parties, encouraging more eye gazing and bonding, which in turn further increases oxytocin levels.
Oxytocin is thought to have evolved as a way to bond a mother and her child in mammals; how did this interaction come to be across species? The researchers tested the interaction between humans playing with wolves that were familiar with one another, and found no oxytocin increase in the wolves. This led the researchers to believe that the oxytocin connection between mammal parents and their children was hijacked long ago during the domestication process of dogs. As humans and dogs lived together more and more, they co-evolved this oxytocin trait between species.
Further corroborating the hijacking theory, the researchers also shot oxytocin nasal spray into 27 male and female dogs and allowed them to walk around and freely interact with their owners and strangers. Female dogs showed an increase of gazing toward their owners, but not male dogs, suggesting the effect is at least in part due to the maternal bonding.
For more dogs in the world, enjoy the “puppy eyes” in this adorable, amazing dog sledding experience in Greenland: