for National Geographic News
The recent outpouring of support for victims of natural disasters may be the sign of a uniquely human trait: Chimpanzeesour closest living relativesare apparently indifferent to the needs of others, according to a new study.
The research probes the question of why humans have altruistic tendencies.
"This is a very hard question and [is] bound to be very complicated," said Joan Silk, an anthropologist at the University of California, Los Angeles. "We are trying to converge towards an answer by using different methods."
With her colleagues, Silk, who studies the evolution of primate behavior, tested two groups of captive-raised chimpanzees for signs of empathy and concern for others.
The team found chimpanzees are indifferent about doing their neighbor a good deed, even if it causes them no inconvenience. Sometimes they'll do it, sometimes they won't.
Craig Stanford, an anthropologist at the University of Southern California in Los Angeles, said the study is "intriguing" but cautioned against drawing firm conclusions from the results.
"My feeling is insight gained from [captive] raised chimps that have to do with bonding and human-chimpanzee interactions are limited," he said. The behavior of wild chimps may be different, he suggested.
John Mitani, an anthropologist at the University of Michigan in Ann Arbor who studies apes in the wild, said this is "a lovely experiment" that points to a behavioral difference between humans and chimpanzees.
"There are some things you can't examine in the wild, which is why you bring the problem into the lab," he said. "One of the strong points of this experiment is they are looking at a question that is very hard to address in the wild."
Silk's team reports its findings in tomorrow's issue of the journal Nature.
In the study Silk and colleagues presented chimpanzees with an apparatus that gave them two options: They could pull a rope to serve food only to themselves or they could serve themselves and another chimpanzee in an adjacent cage.
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