An international team of researchers has found that both chimpanzees and human children are willing to pay to see the punishment of someone who has behaved badly. In their paper published in the journal Nature Human Behavior, the group describes two series of experiments they carried out, one with chimpanzees in a zoo, the other with children aged four to six in a laboratory, and what they learned from them.

Most people know that humans derive some degree of pleasure when watching the punishment of those deemed bad. In this new effort, the researchers sought to learn more about this behavior by testing it in children and comparing what they found to reactions by chimpanzees.

In the first experiment, the researchers enlisted the assistance of several adult chimpanzees. Each was brought alone into a room where they interacted with a human researcher. In some scenarios, the human showed kindness by offering the chimp some food. In other scenarios, the human acted mean by not sharing a food snack. After each scenario, another human entered the scene carrying a stick which was used to (pretend) beat the first human as the chimp watched for a few seconds. Then, both actors moved to another room where the chimp could only follow the action if he worked hard to pull back a door. The researchers found that the chimps were quite eager to see the "bad" human beaten further, as evidenced by the effort to push open the door. Conversely, they did not even try to open the door to watch the action as the "good" human received more punishment.

In the second series of experiments, the researchers enlisted the assistance of 72 children between the ages of two and six—each was asked individually to watch a puppet show in which a puppet offered the child a favorite toy—in some scenarios, the toy was given, in others, it was withdrawn. Then, another puppet appeared and began beating the first puppet. Shortly thereafter, the action moved behind a screen. If the child wanted to continue watching what happened between the puppets, they had to offer up coveted stickers. In watching the action, the researchers found that the older children were willing to give up stickers to watch the "bad" puppet receive more abuse, but not to see the good puppets get beat more. Children younger than six, however, were willing to give up stickers in either scenario, suggesting they did not understand what was occurring.

The researchers suggest the behavior similarities between the chimps and children offers evidence of a shared trait that came about during a time before our ancestors split on the evolutionary tree.

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