学进去

“I like pigs,” Winston Churchill supposedly once said. “Dogs look up to us. Cats look down on us. Pigs treat us as equals.” Whether Churchill’s contemporary George Orwell also liked pigs is less clear. But he, too, surely saw something in them that was lacking in many domestic (驯养的) animals, for it was they who ended up running the show in his novel, Animal Farm. Pigs, then, are intelligent social creatures.

And, like all animals, they sometimes fight. Some pigs tend to be attackers; others tend to be victims. Who is what depends largely on weight. Among pigs, pounds mean power. The attacker might bite, kick or push the victim. Most conflicts end in seconds, but some last a minute or two.

In most animal species fights would be like that. However, many of the conflicts among pigs Dr Norscia, a biologist, observed had interested parties beyond the fighters. He therefore wanted to understand the role of these bystanders in solving conflicts—and what this says about pigs’ cognitive (认知的) abilities.

Since there was usually not enough time for a bystander pig to become involved in the heat of a conflict, though this did occur, Dr Norscia looked at what happened in the three minutes immediately following a fight. Sometimes, he found, the fighters reconciled with each other on their own. The more distantly related the fighters were, the more frequently this happened. Dr Norscia guessed that relations between close relatives are more secure to start with, so rebuilding friendly relations rapidly is less necessary for them.

On other occasions, however, a third pig stepped in. Sometimes this bystander interacted with the attacker, which reduced the number of attacks coming after. Sometimes, the bystander interacted with the victim. This appeared to calm the victim down, for it reduced anxiety-related behavior.

Social intelligence need not, though, be entirely selfless. Pigs are more likely to step in after a conflict if they are closely related to either the attacker or the victim. This is probably an example of kin selection (亲属选择), which favors the development of behavior.