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The Puppy Eye: Oxytocin Induced Bonding Between Dogs and Human

As any dog lover, owner or keen observer may have experienced, dogs have a tendency to gaze at us with their big, round, begging eyes… a phenomena referred to as “puppy eyes”. With this specific gazing behaviour, dogs have a way of melting our hearts and reeling in feelings of love and sympathy. Studies suggest that these bonding moments increase oxytocin levels in both dogs and humans.

Miho Nagasawa and her team from Azabu University believe that this gazing behaviour creates a positive oxytocin feedback loop between dogs and humans. From their 2015 study published in Science, Nagasawa and her team suggest that cohabitation and social relationships between humans and dogs eventually led to dogs exhibiting human-like social communication (ie. mutual gazing). They also hypothesized that the evolutionary development of dog and human relationships resulted in an interspecies bonding similar to mother-infant relationships.

Oxytocin-Mediated Bonding

Oxytocin is a neurological chemical related to social interactions and bonding, and is sometimes referred to as the “love hormone”. In particular, oxytocin is important for mother-infant bonds, where the level of attachment between mother and child can be seen with gaze, touch and vocalization. The study suggests that maternal oxytocin is positively affected by the duration of the mother to infant gaze.

Nagasawa and her team conducted a study to see how the gazing behaviours of dogs would change when given a nasal spray of oxytocin. For the experiment, dogs were given either a nasal spray with oxytocin or saline. They were put in the experiment room with their owner and two unfamiliar participants who were not allowed to talk or touch the dog. The team found that gazing behaviours increased more with female dogs than male dogs, and that owners who experienced the long gazing had higher concentrations of oxytocin in their urine afterwards. The idea of maternal oxytocin among female dogs can leave us with some food for thought. Which shows the need for further research on whether gender plays a role in oxytocin-mediated bonding between dogs and humans.

Overall, Nagasawa and her team suggest that mutual gazing behaviour elicits affection and attachment between humans and dogs similar to that of mothers and infants. So with this is mind, could dogs have picked up their puppy eye behaviour from observing humans?

Not-So-Wild Behaviour

Nagasawa and her team also tested urinary oxytocin concentrations of dogs, wolves and owners before and after a 30 minute interaction (gazing, talking and touching). The dogs and owners were divided into a long gaze group and a short gaze, and were then compared to the wolf group. They found that dogs and owners with longer gaze interactions experienced higher levels of oxytocin than the short gaze and wolf group.

However, Nagasawa’s study does not address whether or not they studied wolf-dogs breeds (and if so, the percentage of wolf in the mix). They work under the assumption that unlike dogs, wolves see eye contact more as a threat as opposed to social communication. Comparing the dogs with wolves, their closest living relative, the study suggests that the “puppy eyes” phenomena evolved with domestication and human-dog bonding. This gazing behaviour has moved from being an intraspecies bond between mother and child, to an interspecies bonding opportunity.

Throughout the long history between humans and dogs, our furry friends may have picked up on human mannerisms to elicit bonding moments. They gaze at us with their big, cute puppy eyes and before we know it our love hormones are being fired left and right. Not only do humans benefit, but dogs can also get a healthy dose of oxytocin as we mutually interact with them. So next time we fall into the puppy eyes trap, we can think about how far we’ve come to bond with this species we now call man’s best friend.

Image Credit: Bob/Flickr

Reference
Nagasawa, M., Mitsui, S., En, S., Ohtani, N., Ohta, M., Sakuma, Y.. . Kikusui, T. (2015). Oxytocin-gaze positive loop and the coevolution of human-dog bonds. Science,348(6232), 333-336. doi:10.1126/science.1261022

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