Pigs rival dogs as 'man's best friend' in the way they engage with us but are more likely to try to solve problems on their own, a study has found.
Experts from Hungary compared the behaviour of young dogs and miniature pigs in experiments involving recovering food from a solvable or impossible puzzle.
They found that, like pooches, pet pigs will turn to humans for support — unless they have problem to solve, when their independent side shines through.
While swine may not be replacing working dogs any time soon — like 'Babe', the 1995 movie about a pig that dreams of herding sheep — they do make great pets.
Like dogs, they are social animals that enjoy living in groups — and the development of genetically-engineered micropigs has made the easier to keep in the home.
The petite porkers are both intelligent and — despite their reputation — fastidiously clean. They can live some 20 years as household pets and get along with cats.
Celebrities known to have kept pigs as pets include George Clooney, Miley Cyrus, David Beckham, Megan Fox, Mario Balotelli and Paris Hilton.
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'Dogs — already as puppies — are known to be uniquely skilful in communicating with us, even without any specific training,' said paper author and ethologist Linda Gerencsér of Eötvös Loránd University in Budapest, Hungary.
'We were curious whether family pigs also exhibit similar communicative signals as dogs, and whether they spontaneously rely on human cues.'
'In the presence of food, both pigs and dogs oriented more towards the experimenter, they touched her more often and looked at her face more frequently,' explained paper author and ethologist Paula Pérez Fraga, also of Eötvös Loránd.
'The similarities we found between the two species point to their similar capacities for engaging in communicative interactions with humans,' she added.
'As an interesting difference, though, only dogs and not pigs looked up at the human face when they did not expect to receive any food.'Dogs are known from an early age to look at humans in a problem-solving context to establish joint attention and initiate interactions, Ms Pérez Fraga added.
The researchers wanted to find out if this is a behaviour unique to 'man's best friend' — or whether other companion animals would do the same.
'Similarly socialised wolves and cats communicate less with humans than dogs in the same problem-solving context, but maybe it is because wolves are not domesticated and cats are not a social species,' said Ms Pérez Fraga.
'So we designed a study to compare dogs' behaviour with that of another domestic and social species, the pig.'
'We used the so called "unsolvable task paradigm", where the animal first faces a problem that he can solve, in our case an easy-to-open box with food inside,' explained Ms Pérez Fraga.
'After some trials, the problem becomes unsolvable because the box is securely closed.'
'When the box was first in the room, without food in it, pigs and dogs performed similar human-oriented behaviours,' said Dr Gerencsér.
'The differences appeared when we put food in the box — and opening it became an exciting challenge.'
'Pigs were faster than dogs already in solving the task and getting the reward, perhaps due to their better manipulative capacities.'
'Then, when the task became unsolvable, dogs turned to the humans more than before. In contrast, pigs performed less human-oriented behaviours.'
The pigs, she added, were more persistent than dogs in trying to solve the task — which may reflect their predisposition to solve problems independently.'
According to Ms Pérez Fraga, 'species-specific predispositions' might be responsible for the differences in behaviour identified in the study.
'Dogs are naturally more dependent on and co-operative with humans. This explains their unique success in interacting with us,' she added.
According to the researchers, the study by the Eötvös Loránd University's 'Family Pig Project' — which was launched in 2017 — is the first to analyse the similarities and differences between family dogs' and pigs' interactions with humans.
'The animals are raised in a similar environment as family dogs from as early as 6–8 weeks of age, which provides the basis for unique comparative investigations between these two species,' said principal investigator Attila Andics.
'We think the primary difference between pigs and dogs lies in the fact the natural salience of the human as a social stimulus for dogs can facilitate learning about communicative cues even without specific training,' she added.
'Furthermore, our results are also informative with regard to the potentials of involving miniature pigs in comparative [animal behaviour] research.'
The full findings of the study were published in the journal Animal Cognition.