Chimps Can Be Team Players, Selfless Helpers, Studies Show
for National Geographic News
|March 2, 2006|
Do you volunteer at your local food bank? Donate blood? Give to charity?
Providing help, without any benefit to yourself, is called altruism, and some scientists have proposed that it is a uniquely human behavior.
But in today's issue of the journal Science, two studies suggest that our closest relatives may also lend a hand in humanlike ways.
In the first study, researchers looked at altruistic behavior in both 18-month-old human infants and young chimpanzees (photo: young chimp).
Various scenes were acted out for the young in which an unknown adult had trouble achieving a goal, like reaching for an object or stacking books.
Ten different situations were presented to 24 infants and three human-reared chimpanzees.
As a control, the same tasks were also done with no indication from the adults that they were having problems.
The results showed that almost all of the children22 out of 24helped at least once and did so almost immediately.
The chimps demonstrated similar, though less robust motivation.
They helped in all five tasks involving reaching but not in more complex situations, like those involving physical obstacles.
The researchers believe both children and chimps are willing to help but that they differ in their abilities to interpret when help is needed.
"It's been claimed chimpanzees act mainly for their own ends, but in our experiment there was no reward, and they still helped," said Felix Warneken, study co-author.
Both studies were conducted by researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Signs of altruism in chimps may mean that the animals already had some rudimentary helping skills before humans split from them about six million years ago, the researchers note.
"Perhaps there was a tiny bit of altruism in our evolutionary ancestor and it's grown so much stronger in modern humans," Warneken said.
But in the wild, unrelated chimps rarely help one another, says Anne Pusey, director of the Jane Goodall Institute's Center for Primate Studies at the University of Minnesota.
As an example she points to a study that showed chimpanzee mothers did not help their infants learn how to fish for termites.
"You would think that mothers watching their kids failing to get termites out of a mound might help them, but in fact they did not," she said.
Chimps raised by humans are considered by some to be behaviorally different from those in the wild, Pusey said, which might explain why the study's chimps offered help.
Chimps Collaborate, Too
In the second study, researchers found that chimpanzees recognized when collaboration was necessary and chose effective partners.
"We've never seen this level of understanding during cooperation in any other animal except humans," study co-author Alicia Melis said.
In the experiment, which took place at a chimpanzee sanctuary in Africa, two chimps had to pull a rope at the same time in order to drag a tray of food toward them.
Melis found that the chimpanzees only let a partner into the room, by opening a door, when the rope ends were too far apart to pull on their own.
"Not only did they know when they needed help, they had to go out and get it," she said.
Just like people, some chimps were better cooperators than others.
For example, a dominant chimpanzee, named Mawa, was impatient and missed opportunities to get the food. But another, named Bwambale, was a team player and almost always successful.
At first the chimps chose Mawa and Bwambale equally for help.
But once they learned what a hopeless cooperator Mawa was, most chimps chose Bwambale on the next trial.
"Clearly chimps can remember who's a good and who's a bad collaborator," Melis said. "Bad collaborators suffer by not being chosen next time."
She points out that there is no evidence that chimpanzees communicate with each other about a common goal like children do, or that they can learn how good a partner is by watching him or her interact with others.
"It just suggests that when chimpanzees cooperate they understand a bit more than we thought," she said.
"Hopefully, future studies can show us what it is that makes human cooperation so unique."
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