Scientists: dogs can cry with joy at the sight of the owner

New studyIncrease of tear volume in dogs after reunion with owners is mediated by oxytocin / Current Biology Japanese scientists have scientifically confirmed that dogs miss their owners. It turned out that when meeting with their owner after separation, dogs literally cry with happiness: their eyes produce more tears than when meeting other people or the owner who was previously at home.

This behavior is explained by increased production of oxytocin, a hormone that plays a key role in forming emotional bonds in both humans and dogs. The author of the study, Takefumi Kikusui, was inspired by his own dog for this idea. 6 years earlier, she had puppies, and Kikusui noticed that her eyes were constantly shining with tears.

The scientist knew that the pet should have increased levels of oxytocin, which has a reputation as a hormone of love and motherhood: it helps stimulate childbirth and breastfeeding. In humans, its levels are also known to rise during pleasurable emotional interactions. That's why some people cry after sex or simple hugs.

Early research is already assumedOxytocin-gaze positive loop and the coevolution of human-dog bonds / Sciencethat the mechanisms of emotion formation in humans and dogs are quite similar, so the Kikusui team hypothesized that dogs produce oxytocin when interacting with other animals and people. But it needed to be checked.

For the experiments, 20 volunteer owners of dogs were invited. Scientists observed the behavior of animals in different situations and measured the volume of liquid in their eyes. (unlike humans, dogs' tears do not immediately flow in streams, but first accumulate on the surface eyes).

In one scenario, the owners simply stayed around and interacted with the dog as usual; in the second, they left and returned five to seven hours later; and in the third, the dogs were left in a zoo hotel, where they interacted both with the owners and with other familiar people. It turned out that after reunion with the owner, the tears were much more abundant, while the animals did not react in this way to other people.

To confirm that it was oxytocin, a second experiment was conducted. The researchers gave the dogs eye drops containing oxytocin or a placebo. Dogs given oxytocin actually produced more tears.

As a result, scientists came to the conclusion that dogs can indeed shed tears of joy when reunited with the owner, and oxytocin is responsible for this reaction.