Friendly Eyes

dogeyesAnyone with a dog or who has spent time around a dog knows the power of the ‘puppy eyes’ well. It’s that piercing look, topped with expressive eyebrows that make you say, “Sure Fido, you can have some of my filet mignon, most of the bed space, and half of the couch.” It’s a look that takes some serious resolve to resist and if it’s accompanied by a mournful sigh, all bets are off. But now research shows that we’re not just slaves to our pets, and are actually experiencing a hormonal response when we make prolonged eye contact with our dogs.

Japanese animal behaviorist Takefumi Kikusui performed a small study on owners and their dogs. The resulting data showed that when dogs and owners interacted with each other and spent time gazing into each other’s eyes, both parties experienced a significant increase in oxytocin hormones. According to urine samples taken before interaction and 30 minutes after interaction, dog owners increased their oxytocin levels by 300 percent and the dog oxytocin levels rose by 130 percent. No effect was seen in the dog/owner pairs that did not spend significant time looking at each other, emphasizing the importance of gaze. The outcome is not entirely surprising, given that oxytocin is frequently referred to as the ‘cuddle’ or ‘trust’ hormone; its release is triggered when mothers gaze into the eyes of their newborn baby.

But what was perhaps slightly unexpected was the mutual response observed, demonstrating how our relationship with household pets is not one-sided. The hormonal response to dog-human interaction could provide valuable insight into canine domestication, and also provide a bit of validation for dog owners (it turns out we’re not completely insane to treat our pets as children after all). Kikusui and his group then performed a second experiment in which they administered oxytocin via nasal spray to the dogs. They saw that the female dogs spent a longer period of time gazing at their owners, while the male dogs remained unaffected. This indicates that the same oxytocin-mediated positive feedback loop observed in mothers and children is also initiated between owners and dogs.

But how does it actually work? Oxytocin falls into a category of molecules called hormones, which are involved in helping cells signal to each other. Its most prominent role in human biology is the stimulation of childbirth, but more recent studies have shown that it heavily affects our trust and bonding capabilities as well. As previously mentioned, it was found that it is released from the brain when mothers look into their baby’s eyes, and further studies demonstrated that it may be responsible for a number of social behaviors. It was also tested as a ‘trust’ hormone when researchers gave it to subjects in the form of a nasal spray. From these experiments they found that after receiving oxytocin, subjects were much more likely to entrust money to a stranger. Neuroeconomist and oxytocin researcher Paul Zak claims that oxytocin is “the ultimate moral molecule,” though other studies have indicated that it can induce deceit in the interest in the greater good. So while the oxytocin field has many compelling research applications that go beyond love and cuddling, it is comforting to know that the key to an oxytocin boost lies in the eyes of our best friends.

Susan Gelman

Susan Gelman is a graduate student in the chemistry department at Washington University in St. Louis, with an emphasis on biological chemistry. Her research focuses on metabolomics and cancer metabolism.

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