Why we love dogs like babies

Paris Hilton with her 'baby'. Photo / Getty

Dog owners love their pets in the same way as they do their children, and the feeling is mutual, scientists have found.

Researchers found that the levels of the hormone oxytocin increases in both human and canine brains when a dog is gazing at its owner.

Oxytocin is known to play a strong role in triggering feelings of unconditional love and protection when parents and children look into each other's eyes or embrace.

The findings suggest owners love their pets in the same way as family members, and dogs return their devoted affection.

"These results suggest that humans may feel affection for their companion dogs similar to that felt toward human family members," said Dr Miho Nagasawa, from the department of animal science at Azabu University in Sagamihara, Japan.

"Oxytocin plays a primary role in regulating social bonding between mother and infants and between sexual partners."

The researchers from the University of Tokyo and Duke University in the United States believe that oxytocin creates a "neural feedback loop" that has strengthened the bond between humans and dogs for millennia.

To test the theory, researchers put dogs in a room with their owners and documented every interaction between them, such as talking, touching and gazing.

They then measured levels of oxytocin in urine and discovered increased eye contact between dogs and humans had driven up levels of the hormone in both species.

However, when they performed the same experiments on wolves raised by humans there was no increase in oxytocin, suggesting it evolved during the domestication of dogs that began 34,000 years ago.

Dr Evan MacLean, a senior research scientist at Duke University, said that dogs had learnt to "hijack" the bonding pathway between parents and their children.

"It's really only in the last couple of thousand years that we have kept dogs as pets, and dogs began to be able to relate to humans in meaningful social ways," he said.

"They became attuned to our social cues in the way that young children are. For example, when dogs are presented with an impossible task they quickly turn to humans to see what to do, just like children do. Wolves don't do that.

"Our relationships with dogs are very much like parent-child relationships.

"We respond to our dogs quite a bit like human children. Brain imaging studies have shown that brain networks of mothers respond in the same way to pictures of their own dog to their own children.

"One evolutionary scenario might be that dogs found a way to hijack these parenting responses and dogs over time may have taken on more childlike and juvenile characteristics to further embed themselves into our lives."

The researchers say that the paper, published in the journal Science, shows that dogs feel like a child of the family.

In a second experiment, the researchers sprayed oxytocin into the noses of dogs and put them in a room with their owners and some strangers.

Female dogs responded to the treatment by increasing the amount of time that they gazed at their owners.

After 30 minutes, in further evidence of the feedback loop, oxytocin had also increased in owners of the treated dogs.

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