Eye contact between a mother and her baby strengthens their attachment by activating the so-called 'love hormone' – oxytocin – in the mother’s brain.

This drives emotional bonding between parent and offspring by encouraging both nurturing and interactive behaviours.

Studies have shown that stroking or making eye contact with a dog can trigger a similar release of oxytocin in a human’s brain.

Now a team of Japanese scientists have found that the “mutual gaze” between dogs and their owners can lead to a bond that is similar to that between a mother and child, with humans experiencing the same feelings of affection for their dogs as they might do for their family, therefore helping to bring the species closer.

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The findings are reported in the journal Science and also note that wolves do not show the same response. Authors suggest this means that the bonding process probably co-evolved in both species as dogs became domesticated.

“It can be said that dogs successfully cohabit with humans because they have been successful in adapting the bonding mechanism to relations with humans,” said lead author Dr Miho Nagasawa, from the School of Veterinary Medicine, Azabu University, Japan.

“Dogs originally had this mechanism with the same species, but humans also went through some sort of evolution that allowed them to bond with other species, that is dogs.”

Dogs were observed for 30 minutes in a room with their owners, the amount of time the dogs made eye contact with their owners was used to put the dogs into two groups: long gaze and short gaze.

Wolves differ

The dogs that gazed at their owners the most saw a significant increase in their oxytocin levels after the experiment, the increased eye contact had also driven up levels of the hormone in their owners’ brains.

In a second experiment oxytocin was sprayed onto the nose of some dogs before they were put into a room with their owner and two strangers for 30 minutes without any interaction from the humans.

They discovered that female dogs looked at their owners for longer, and that the owners of these dogs released more oxytocin.

The lack of an effect on male dogs could be down to sex differences in the function of oxytocin, according to the authors.

The researchers suggest that these results show the existence of a continuous bonding loop between humans and dogs, driven by oxytocin.

A dog’s eye contact with its owner sparks the release of the hormone in the human’s brain, which leads to the owner wanting to interact more with their dog. This in turn sees an oxytocin spike in the dog.

When the first experiment was repeated on wolves that had been raised by humans, the authors found no evidence of a similar bonding loop, suggesting they do not use the same communication skills with humans as dogs.

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