Empathy

When the animals are confronted with a human displaying strong feelings, they themselves produce a similar emotional response, the researchers found.

The discovery could cast light on how dogs' pack behaviour has been translated into the modern world.

Biomedical scientist Dr Karine Silva, of the University of Porto, says that dogs even possess certain human-like social skills that chimpanzees, our closest relatives, do not.

Writing in the Royal Society journal Biology Letters, she says the animals' response goes beyond simply mimicing their owners' - a reaction known as "emotional contagion".

Dr Silva said: "A study showing that pets, namely dogs, behave as 'upset' as children when exposed to familiar people faking distress, strongly suggests 'sympathetic concern'.

"Also, it has been reported that untrained dogs may be sensitive to human emergencies and may act appropriately to summon help, which, if true, suggests empathic perspective taking."

The researchers believe there are three main reasons for dogs empathising with human.

Modern pets originated from wolves which are highly social animals that engage in co-operative activities and have developed empathy towards other animal species.

Furthermore, biological chances as dogs were domesticated mean their empathy towards man has been fine-tuned over generations.

And breed diversification and selection for increasingly difficult working tasks, such as herding animals or hunting, have led to more complex understanding of human emotional communication.

The researchers said despite limited research they consider dogs' capacity for emotional contagion and perhaps for some mental processing of humans' emotional states is supported by both anecdotal and experimental data.

One study published 18 months ago found pet dogs tend to yawn when they see people doing the same while another reported five years ago showed pet pooches' stress hormones rose or fell in direct relation to their owner's.

Dr Silva and colleagues said: "Curiously, contagious yawning has been connected to higher levels of empathy in humans, with studies suggesting that it probably shares a developmental basis with self-awareness and perspective taking."

They said research on the empathic abilities of dogs is of special importance for decisions about our obligations towards them.

The researchers went on: "Clearly, there is a need for additional investigations to analyse the emotional and cognitive components that may be involved in dogs' seemingly empathic behaviour towards humans."

They added: "Dogs have been increasingly involved with human activities and further studies are crucial if specific needs are to be met.

"For instance, it would be important to conduct rigorous tests on therapeutic dogs that seem to 'take on' the emotions of patients, needing massages and calming measures after the sessions.