LONDON (Reuters) - An angry chimpanzee will take revenge but -- unlike a human -- it will not do so out of spite, according to a study published on Monday that offers insights into how people perceive what is fair.
The study showed chimpanzees would seek retribution when wronged but did not punish others out of spite, for instance if another chimpanzee was better off, said Keith Jensen, an evolutionary biologist at the Max Planck Institute in Germany, who led the study.
Scientists had debated whether a sense of fairness and social comparison applied only to humans and the study was an attempt to answer some of the questions, Jensen said in a telephone interview.
“Like humans, chimpanzees retaliate against personally harmful actions, but unlike humans, they are indifferent to simply personally disadvantageous outcomes and are therefore not spiteful,” he and colleagues wrote in a study published on Monday in the Proceedings of the Natural Academy of Sciences.
The study suggests that anger is an important motivational force but what causes it differs greatly between chimpanzees and humans, Jensen said.
“Humans and apes both get upset at theft but humans are more likely to get upset at unfairness,” he said.
The researchers explored how chimpanzees responded to loss and theft by putting them one at a time in a small room with access to food on a sliding table in a booth outside.
Each animal held a rope allowing it to collapse the table and send the food out of reach. Unsurprisingly, the chimpanzees chose not to collapse the table while eating, researchers said.
When the researchers made the food on the table viewable but out of reach to the first chimpanzee or when a second animal could eat in plain view of the first, the chimpanzees did not seem to care.
When the second animal was able to take the food away from the first, the chimpanzee without food often collapsed the table to take revenge, the researchers said.
“The final situation was punishment where theft was involved,” Jensen said in a telephone interview. “The only option for the victim in this situation was to collapse the table and nobody eats.”