Pigs can be optimists too, British researchers say
We're not the only ones who can wear rose-coloured glasses. Little pink pigs can as well.
So said researchers at the University of Lincoln in England, who wrote a new study concluding that pigs' personalities combine with their moods - yes, swine have both of those things - to make them optimists or pessimists. Scientists already knew this was true for humans, but the authors said this is the first time it has been demonstrated in an animal.
Pigs' personalities combine with their moods - yes, swine have both of those things - to make them optimists or pessimists. Credit:Katherine Griffiths
To determine the influences on pigs' outlooks, researchers first administered personality tests to 36 pigs younger than two months, said Lisa Collins, a co-author of the study, which was published in Biology Letters. The pigs were presented with something they'd never seen before and might be a bit scared or wary of: an orange traffic cone. Those that rushed up to explore it were labelled "proactive" pigs (the kind of pigs that, in other studies, have been shown to be more dominant and aggressive, Collins said). Those that were more cautious about the cone were deemed "reactive" - and reactive pigs are more likely to be victimised in porcine groups.
Next, the pigs were divided into two kinds of lodging. Half got quarters typical to a British commercial pig farm, with concrete floors and a slatted "toilet" area. The other half got a "really cushy-plus version," Collins said, which in pig terms means more space and lots of straw in which to root and lounge. Previous research has found that such differences can affect pigs' moods, which is judged based on behaviour, body condition and other factors. The video below shows some of the pigs and explores the idea of animal mood.
Each pig was trained to associate a bowl in one corner of its room with something the animals love (M&Ms, Collins said) and a bowl in another corner of the room with something they don't (coffee beans). Once the pigs learned to eagerly run to what was always the M&M corner, the researchers presented them with bowls placed in "ambiguous" places - between the corners where they were used to seeing bowls. The ambiguous ones were empty, Collins said, to ensure the pigs didn't rely on smell to make their decision.
And that decision was the optimist/pessimist test: Would the pigs rush to the bowl, optimistically expecting chocolate even when it was in a new spot? Or would they pessimistically figure it wasn't worth the effort?
It turned out that the reactive pigs "on the whole tended to be more optimistic," Collins said, and the reactive pigs that were in the cushy conditions - and presumably in a good mood - were the most likely to run for M&Ms. Proactive pigs were always more pessimistic.
"Their personality type really affected the way they responded" to the test, Collins said.
Collins and her colleagues are interested in this from a farm-animal perspective (sorry, vegetarians). Proactive animals on pig farms tend to pick on others and be seen as "the naughty kid in the class," but this finding indicates their personality means "they see the world in a much more pessimistic light. They're not able to cope with change," she said.
That's important from an animal welfare perspective. Conditions matter, but farmers need to take individual animals into account, too, she said.
"With commercial animals being raised in huge numbers, the tendency is to look at them as a member of a group - not like clones, but like they're all very similar and they'll all respond in very similar ways," Collins said. "And what this research shows us is that absolutely isn't the case."
The Washington Post
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