Dogs can copy each other's expressions in a split-second just like people, according to Italian researchers.

Mimicking each other's facial expressions is a human habit, which helps people to get along. Dogs do the same to bond with other dogs, scientists report in the journal, Royal Society Open Science. They think dogs may be showing a basic built-in form of empathy, enabling them to pick up on emotions. And the phenomenon may have emerged in our canine companions during the process of domestication, say scientists from the Natural History Museum, University of Pisa.Until now, the idea - involved in social bonding - has only been described in humans and non-human primates such as chimps and orangutans. It is why humans automatically mirror a smile or a laugh, enabling the sharing of emotions.

The team of three researchers - working with the Unit of Cognitive Primatology and Primate Center in Rome - videotaped dogs playing in a park in Palermo, Italy. They analysed the way the dogs were interacting, including signals used to show when a dog was being playful, such as:

• Crouching or "bowing" down on its front legs
• Relaxing its mouth to reveal some of its teeth

After analysing 50 hours of video, they found that dogs were able to mimic the facial expressions and movements of other dogs in a split-second.

This "rapid mimicry" is an automatic and involuntary response, rather than the result of training, they say.

But Dr John Bradshaw of the University of Bristol School of Veterinary Science said more research was required to establish if dogs are really able to sense what emotions are uppermost in the minds of other dogs. "Domestic dogs are exquisite readers of body-language, both that of other dogs, and, uniquely, our own - which is why they're so easy to train," he said. "They also love to play, so quickly learn that imitating the actions of their play-partner means that the game goes on for longer. "But science has yet to show that dogs have any understanding of other dogs' thought-processes, or emotions." Dogs are known to be able to respond to human emotions, such as copying a yawn, suggesting they show some basic aspects of empathy.

This capacity may have evolved in dogs as they were domesticated or could have been present in the wild ancestors of canines. The Italian researchers plan to study wolves to answer this question and shed more light on the complex relationship between humans and dogs.