Rob a bank and it won't be the teller[出纳员] who sentences you to jail, but rather a judge. This is known as third-party punishment, in which individuals punish violators even when the violation doesn’t directly affect them, and it’s critical to the maintenance of cooperation in human societies.
But dominant[占优势的] chimpanzees, who dish out[给予] punishment when stolen from, turn a blind eye unless the theft directly affects them, according to a new study. Researchers gave captive chimps the chance to punish those who stole food. In one experiment, the "actor" chimp watched as a "thief" pulled food away from a "victim." The actor could then push a button to release a trapdoor[活板门] in the cage, causing the food to fall out of reach of the thief.
Dominant actors punished thieves who stole from them, but not those who stole from others, even when they were related to the victim, the researchers report online today in the Proceedings of the National Academy of Sciences. The findings suggest that third-party punishment evolved in humans after we diverged from our closest living relatives.