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The latest research into pigs may leave some reluctant to tuck into a plate of sausages again.

Scientists have discovered that the creatures may be capable of empathy – a characteristic thought to be almost uniquely human.

In an elaborate experiment, experts discovered that pigs shared the stress and happiness of their penmates.

Emotional: In an elaborate experiment involving training some pigs to anticipate a reward or punishment, scientists discovered that untrained pigs shared the stress and happiness of their penmates

This findings suggest that swine respond to each other's feelings, and adds weight to the argument that the practice of separating the animals in farms is especially cruel.

Scientists at Wageningen University in the Netherlands set out to investigate whether pigs can show empathy to one another, defined by renowned primatologist Frans de Waal as 'the capacity to be affected by and share the emotional state of another, assess the reasons for the other's state and identify with the other, adopting his or her perspective'.

They housed pigs in 16 groups of six, training two of the animals in each of the groups, Scientific American reported.

Scientists at Wageningen University in the Netherlands set out to investigate whether pigs can show empathy to one another (illustrated witha  stock image) just like humans and other animals that comfort each other

The pigs were trained either to anticipate happiness or distress, by playing them music and either rewarding them with a pleasant treat such as chocolate raisins and a roomy house filled with peat, or putting them in a stressful situation, such as keeping them in isolation in a small pen.

Untrained, 'naïve' pigs were placed in a pen with a pig conditioned to expect happiness, or one that expected discomfort.

All the pigs were then played the same music – a piece by Bach - used in training.

PIGS AREN'T THE ONLY ANIMALS THAT SHOW EMPATHY

Asian elephants show concern for others when they are stressed, using their trunks to caress the suffering elephant and emit a soft 'chirp,' Discovery recently reported. 

Consoling elephants put their trunk into another elephant's mouth so they are vulnerable, perhaps showing they are there to help.

Crows and ravens are also known to be emotionally intelligent, with researchers at the Konrad Lorenz Research Station in Austria finding that the birds comfort others that are stressed after a fight. Ravens sit next to the distressed bird so their bodies are touching and sometimes preen it.

University of Portsmouth research has shown that orangutans (stock image) can be so full of empathy that they take on the moods of others. When one orangutan laughs, others often join in

Scrub jays - another member of the Corvid family - have 'funerals' for deceased friends, according to research by the University of California, Davis. They fly over the dead body, wailing and screeching, which may be a sign of grief.

Mice have been shown to detect pain among others but only appear to console their family and friends. Garet Lahvis, an assistant professor at Oregon Health and Science University, said: 'Mice are capable of a more complex form of empathy than we ever believed possible.'

Similarly, rats are believed to be able to respond to excitement, fear and anger. They even help each other out with no prospect of a reward, according to Washington State University. The rodents also show that they enjoy being tickled and playing by giggling.

Gorillas not only care for each other but have even been seen to care for dolls.

University of Portsmouth research has shown that orangutans can be so full of empathy that they take on the moods of others. When one orangutan laughs, others often join in.

Some of the trained pigs showed that they anticipated what may happen to them, either by displaying happy behaviours - such as wagging their tails and barking - or signs of stress, such as keeping their ears back, urinating and defecating.

Despite most of the trained pigs failing to react at all, they were still taken to another pen, leaving the naïve pigs behind, and were either rewarded or punished, depending on their training.

The naïve pigs, which could not have known what lay in store for their penmates, reacted to the trained pigs' behaviour anyway.

For example, when a trained pig showed it was stressed, a naïve pig acted in the same way, by becoming more alert and keeping its ears back.

The behaviour was even more noticeable when the untrained animals noticed the behaviour of trained 'happy' pigs, with the animals becoming more playful and wagging their tails.

To test that the animals were responding to each other's behaviour and not simply the music, the scientists played the naïve pigs the tune.

They showed no signs of changing their behaviour, indicating they were showing empathy with the trained animals. 

The findings were published in the journal Animal Cognition.