Captive Chimpanzees Help Others

If you're looking for help from a chimp, don't forget to say please. Captive chimpanzees readily help others obtain an out-of-reach snack, but only if they beg for it, a new study shows.

Researchers have long debated whether chimpanzees act altruistically. In the wild, the great apes exchange grooming duties, and occasionally food such as meat, but whether these transactions fit the definition of altruism is controversial.

"It is difficult to evaluate the cost and benefit of behaviours in the wild and actually impossible to control the situations, and therefore it is disputable to say that it is altruistic behaviour," says Shinya Yamamoto, a primatologist at the Kyoto University in Japan, who led the new study.

Studies of captive chimps, meanwhile, found little consistent evidence for altruism, though one report showed that chimpanzees will lend humans a helping hand.

Enter the chamber

One problem with many of these studies is that they rely on sharing food – – something chimps do with reluctance.

To get around this, Yamamoto's team designed a special chamber with two booths, connected by a small, open window. In one test, one booth contained a large stick, the other an out-of-reach carton of juice. In another, one booth held a straw, the other a carton of juice with a tiny opening. The only way to obtain the juice was to use the tool from the other booth.

In dozens of trials involving six pairs of chimpanzees, one of the chimps consistently offered the tool to the other. But help often came only after the chimp in need reached out its hands or made a ruckus.

Theory of mind?

The relationship between the pairs also made a difference. Three mother-offspring pairs helped each other more frequently than unrelated pairs did – even when the favour was not reciprocated in future trials. Among three pairs of unrelated chimps, the dominant chimpanzee was most likely to request and receive the tool.

Such requests may be necessary because chimpanzees don't fully understand the desires of others, Yamamoto says.

"This is a great illustration of helping behaviour in chimpanzees," says Frans de Waal, a primatologist at Yerkes National Primate Research Center at Emory University. "Until now most research in this area was guided by the question whether the behaviour is selfish or altruistic, but a more interesting question is when is help provided and how intentional does it seem."

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