You and your dog share the same hormone
Oxytocin - the same hormone responsible for helping mothers bond to their infants - increases in both dogs and their owners when they maintain eye contact, the Japanese scientists found.
In a series of experiments, the researchers showed that a positive "biofeedback loop" appears to exist between dogs and humans, whereby a rise in oxytocin in one triggers a rise in the hormone for
the other The findings were published in the April 17 issue of the journal Science.
"Humans have evolved to use human-specific communicative tools, mainly the eye gaze," said study co-author Dr. Takefumi Kikusui, a veterinarian and researcher in the department of animal science and biotechnology at Azabu University in Kanagawa, Japan.
"Eye gaze may be functioning instead of physical touch or hugging. The point is that dogs can show the same communicative gazing toward humans," Kikusui said.
In the first experiment, dogs and their owners interacted for 30 minutes. Those who spent the most timing gazing into one another's eyes had higher concentrations of oxytocin in their urine afterward.
Dog-owner pairs without the lengthy eye gazing did not have the same increase in oxytocin. Owners also touched their dogs and spoke to their dogs more when they had more eye contact with them.
In the second experiment, researchers sprayed oxytocin into the nostrils of 27 dogs and released each into a room with their owner and two strangers. The female dogs spent more time looking at their owners, who also experienced an increase in oxytocin.
When the first experiment was conducted with hand-raised wolves who had bonded with their owners, however, no changes in oxytocin levels were seen from gazing. Wolves typically use eye contact as a threat and avoid human eye contact, the study noted.
The findings suggest that mutual gazing between dog and owner as a form of social communication likely co-evolved as dogs became domesticated and improved bonding between the two species, the authors said. ■