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 Researchers in Japan said on Thursday oxytocin, a hormone that
among other things helps reinforce bonds between parents and their
babies, increases in humans and their dogs when they interact,
particularly when looking into one another's eyes.
They described a series of experiments that suggest that people and
their canine companions have mutually developed this instinctual
bonding mechanism in the thousands of years since dogs were first
domesticated.
Sometimes called the "love hormone," oxytocin is made in a brain
structure called the hypothalamus and secreted from the pituitary
gland. It is involved in emotional bonding, maternal behavior, child
birth, breast-feeding, sexual arousal and other functions.
"Oxytocin has many positive impacts on human physiology and
psychology," said Takefumi Kikusui, a veterinary medicine professor
at Japan's Azabu University, whose research was published in the
journal Science.
In one experiment, dogs were put in a room with their owners. The
researchers tracked their interaction and measured oxytocin levels
through urine samples. People whose dogs had the most eye contact
with them - a mutual gaze - registered the largest increases in
oxytocin levels. The dogs also had an oxytocin spike correlating
with that of their owner.
The researchers conducted a similar experiment with wolves, close
relatives of dogs, and found that no such thing happened despite the
fact that the wolves had been raised by the people.
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In another experiment, the researchers sprayed oxytocin into dogs'
noses and put them in a room with their owners as well as people the
dogs did not know. With the female dogs, and not the males, this
increased the mutual gazing between dogs and their owners and also
led to an oxytocin increase in the owners.
"I personally believe that there is a tight bond between the owner
and dogs," Kikusui said.
"I have three standard poodles. I strongly feel the tight bonding
with these dogs. Actually, I participated in the experiment, and my
oxytocin boosted up after the eye gaze, like 300 percent," Kikusui
added.
The study involved dogs of various breeds and ages including the
miniature schnauzer, golden retriever, border collie, Labrador
retriever, Shiba Inu, standard poodle, beagle and others.
(Reporting by Will Dunham Editing by W Simon)
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