14 DAY TRIAL // Scientists were surprised to discover that chimps are able to help somebody even when they don't expect any reward. Moreover, they are able to exhibit complex cooperative actions and even to go asking for help from a fellow chimp when such help is necessary.
Felix Warneken and Michael Tomasello from the Max Planck Institute did the following experiment. Warneken was hanging laundry as a young chimp was sitting nearby and was capable of observing him. At a certain moment, he "accidentally" dropped a clothes peg. The chimpanzee picked up the peg and retrieved it although he received no reward. All tested chimps manifested the same behavior.
However, when Warneken threw the peg on purpose the chimp did not react. Thus, they were capable of attributing goals - a type of mental action previously thought to be specific to humans only - and inferring from these goals whether Warneken really needed the peg on not. If he dropped the peg by accident the chimp thought he probably needs it; otherwise the chimp has understood Warneken didn't really need the peg. It is also striking not only that the chimps are capable of understanding other people's goals but also that they are willing to help without getting rewarded.
"This is the first experiment showing altruistic helping toward goals in any nonhuman primate," Warneken notes. "It's been claimed chimpanzees act mainly for their own ends, but in our experiment, there was no reward and they still helped."
The scientists did the same kind of experiment with human infants and found them responding twice as quickly in the same situation and that they were willing to help in a larger variety of situations. Warneken thinks that maybe some situations simply didn't make sense to the chimps - for example, the situation when they were supposed to help by opening a cabinet door because he had both hands occupied with a stack of magazines.
In another study, realized by Tomasello and colleagues Alicia Melis and Brian Hare, they have tested the chimps' ability to cooperate. Researchers placed outside the chimp's cage a food tray attached to two distant ropes. The food trey could have been brought within reach only by two chimps simultaneously pulling the ropes.
"The experiments show that chimpanzees spontaneously recognize that when they are faced with a problem they cannot solve on their own they need to recruit help," said Hare.
Not only did chimps go for help but also they selected more frequently the fellow chimp that proved more skill at maneuvering the rope - the so-called "expert".
"Not only did they need to know when they needed help, they had to go out and get it," Melis says. "Then they had to wait until their partner came in and pull on the rope at the same time. The chimps really had to understand why they needed their partner."
This experiment didn't test chimpanzees' generosity but their ability to cooperate and to choose a proper partner. While the first experiment has showed that chimps have an ability of attributing goals to others, this cooperative task involves the ability of choosing the best means for a particular goal.