A group of Japanese scientists say they have found that dogs shed more tears when they are reunited with their owners. The new study says this is a possible trait developed during the animals' process of domestication, as they tried to strengthen their ties with humans.

Researchers at Azabu University published their findings in the magazine Current Biology on Tuesday.

The scientists compared the volume of dogs' tears before and after being reunited with their owners following more than five hours of separation.

They found the amount of tears increased significantly by an average of 15.9 percent after being with their owners. But there was no change when dogs were with someone they didn't know.

The scientists suggest that oxytocin, a kind of hormone released in dogs when interacting with people, also plays a role in tear production.

They also asked people to look at pictures of dogs with and without teary eyes, resulting in positive responses for teary-eyed dogs.

The scientists concluded that dogs may be shedding tears to forge positive relationships with their owners.

Assistant Professor Nagasawa Miho of Azabu University's Department of Veterinary Medicine said that shedding tears may be one of the strategies dogs use to make people take care of them.