BioEd Online

Chimpanzees may be more eager to help than we thought. Research suggests that the apes can understand when a person is in need, and are unexpectedly willing to give aid.

Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have shown that young chimpanzees (Pan troglodytes) will pick up a marker pen and hand it back after their keeper has 'accidentally' dropped it.

The study shows that chimpanzees understand when another is in need, and can help out if they are in a position to do so, according to Felix Warneken and Michael Tomasello, who publish the research in Science¹.

The results are surprising because chimpanzees, although intelligent, are not regarded as being very cooperative unless they get a clear benefit. Last year, anthropologist Joan Silk of the University of California, Los Angeles, found that chimpanzees showed no preference for getting food for the group over eating solo, even when it cost them nothing (see " Chimps fall short on friendship").

Just a game

So are chimps helpful or not? It is unclear, says Silk. She points out that her experiment looked at interactions between chimps, whereas the new study looked at chimps and humans. Things are further complicated by the fact that the new experiment involved interactions between young chimps, aged between three and five years, and their caregivers, who are more like parental figures.

Warneken and Tomasello's study compared the chimps' behaviour with that of 18-month-old humans. The infants helped out adults in more ways than the young chimps, they found, not only handing back dropped items but also spotting when an adult had stacked books clumsily or pointing out the existence of a trap-door that could help the adult retrieve keys dropped into a box.

Such behaviour relies on knowing what the adult is thinking or trying to achieve, claims Silk. But many human-development experts think that this sort of awareness does not develop until around three years of age.

It is difficult to say what motivates the helpfulness of the chimps, although the experiment does suggest that they are aware of the human adult's state of mind, Silk adds.[ok?] "It's hard to know what the kids or the apes were actually thinking - whether they saw it as a game or a chore," she says.

If the youngsters are treating it as a game then their actions might be motivated by enjoyment gained rather than true empathy. "But it seems they do understand the process," says Silk.

Playing favourites

Another study published this week by the Leipzig lab2 looks at how good chimps are at cooperating when they choose to do so. A team led by Alicia Melis showed that chimps living at Uganda's Ngamba Island sanctuary recruit the most expert helpers to give them a hand with tasks they cannot accomplish by themselves.

The researchers placed a food-laden platform outside the chimps' cage that was accessible by pulling a pair of ropes. Pulling just one rope unthreaded it and made the food unobtainable.

Melis and her team taught chimps how to use a simple lock on the door to an adjoining cage, and gave them the option of unlocking the door to let another chimp in to help pull the rope. They discovered that, when they repeated the trial the next day with a choice of collaborators in separate cages, the chimps enlisted the help of the chimp that had been more adept at the task the previous day.

"It's clever and effective," Silk says.

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