You may want to think twice about tucking into that bacon roll.

Scientists have found that pigs are smarter than dogs, and can solve problems just as well chimpanzees.

The study's authors are hoping the results will make people think differently about animals that are traditionally seen as meat.

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Scientists have found that pigs are smarter than dogs, and can solve problems just as well chimpanzees. The study's authors are hoping the results will make people think differently about animals that are seen as meat

'We have shown that pigs share a number of cognitive capacities with other highly intelligent species such as dogs, chimpanzees, elephants, dolphins, and even humans,' said neuroscientist Lori Marino of Emory University.

'There is good scientific evidence to suggest we need to rethink our overall relationship to them.'

The researchers came to the conclusion after looking at dozens of studies conducted on pigs and other animals, and collating the results.

Overall, research suggests pigs have excellent long-term memories, and are skilled at mazes and other tests requiring location of objects.

They can also comprehend a simple symbolic language and learn complex combinations of symbols for actions and objects.

This was shown earlier this year when a video recorded by Nicolle von Eberkopf, who lives in Berlin, Germany, revealed her pet pig doing amazing tricks.

In the video, Moritz the pig places coloured pig-shaped blocks in corresponding coloured holes on a wooden board.

The pig does this using its mouth, without any help.

The researchers of the latest study also believe pigs love to play and are often involved in mock fighting with each other, in the same way as dogs.

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. Advertisement

They have complex social lives, with pigs often learning from one another and cooperating together, according to a report in Discovery News.

A study earlier this year also found pigs have empathy. Researchers in the Netherlands housed pigs in 16 groups of six, training two of the animals in each of the groups.

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.

The study's authors say while we tend to place pigs in a lower category to animals such as dogs and cats, they are in fact, just as smart and empathic – and should be treated as such

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.

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.