"When your dog is staring at you, she may not just be after your sandwich." That's how evolutionary anthropologists frame a new study that describes just how powerful a bond humans and dogs share.

 

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In two experiments, described inScience, both dogs and their owners saw an increase in oxytocin, also known as the "love hormone," just by staring into each other's eyes — the same reaction that occurs when a mother looks at her newborn baby. It's a surprising find considering that domesticated dogs and wolves usually only make eye contact amongst themselves to establish dominance, and the researchers believe it may explain how humans managed to domesticate dogs in the first place. It's possible, they say, that a group of friendly canines looked into the eyes of humans and "unwittingly tapped into the natural human system designed for parent-child bonding," as LiveScience puts it.

Researchers first observed 30 dog owners and their pets and found that after 30 minutes of play, more eye contact between the two during that interaction translated into higher oxytocin levels in both human and canine urine, the Los Angeles Times reports. Such a response was missing in a similar experiment involving wolves and the handlers who'd raised and played with them. 

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In another experiment, researchers sprayed oxytocin into dogs' noses before a play session. Though there wasn't much response in male dogs, female dogs, afterward, made more eye contact with their owners, whose own oxytocin levels spiked. "These results suggest that humans may feel affection for their companion dogs similar to that felt toward human family members," a researcher explains, per the Telegraph