According to new research, eye contact between humans and dogs promotes the production of oxytocin, the tenderness hormone.
"The tongue may conceal the truth, but the eyes never can," wrote Mikhail Bulgakov; indeed, anyone who has a dog knows it — from the animal's gaze an boundless love shines through, and this may well be one of the secrets behind the profound bond that has linked these two species for millennia.
This is the claim of a new study conducted by biologists at Azabu University, led by Miho Nagasawa. According to the research, prolonged eye contact between a dog and its owner increases oxytocin levels in the brains of both. Oxytocin is a hormone associated with happiness and love — the same one that, for example, strengthens the bond between a mother and her newborn through eye contact.
The study, published in Science, argues that the profound relationship between humans and dogs was born when the latter learned to look humans in the eye. The researchers conducted two experiments; in the first, urine samples were collected from twenty-one dog-owner pairs before and after they interacted with each other.
The results showed that oxytocin levels were higher after owners had played with their dogs or spoken to them, but were particularly elevated when they had gazed at their animals for a prolonged period.
The experiment was then repeated with eleven wolves raised by humans, but none displayed behaviour similar to that observed in dogs. "The duration of eye contact between dog and owner is closely correlated with an increase in oxytocin," the study states.
In the second experiment, the researchers sprayed oxytocin into the dogs' noses before releasing them into a room with their owner and two strangers. In this case the results were more pronounced in female dogs, who immediately recognised their owners and increased the time spent gazing at them, prolonging their own happiness and generating it in the human.
Perhaps, in the end, it is not even that important to know why humans and dogs cannot do without each other. We know that it has worked for over 14,000 years, and that whenever we need love, all we have to do is look into our dog's eyes.