*Chimps' Sense of Justice Found Similar to Humans'*
Inequities big and small can lead people to believe that life is indeed
not fair. But how humans respond to unfair situations depends on the
social circumstances: inequality among friends and family, for instance,
is less disturbing than it is among strangers. The results of a new
study indicate that the same is true for chimpanzees, a finding that
sheds light on how our sense of fairness evolved.
In the fall of 2003 Sarah Brosnan and Frans de Waal of the Yerkes
National Primate Research Center in Atlanta determined that capuchin
monkeys don't like being subjected to treatment they deem unjust. In the
new work, the researchers tested the reactions of pairs of chimpanzees
to exchanges of food that varied in quality. The animals received either
a grape, which they coveted, or a less appealing cucumber, and they
could see what their partner obtained. In pairs of chimps that had lived
together since birth, the individual given the cucumber was less likely
to react negatively to the situation than was the short-changed member
of a pair that did not know each other as well. Indeed, chimps in the
short-term social groups refused to work after their partner received a
better reward for the same job. "Human decisions tend to be emotional
and vary depending on the other people involved," Brosnan says. "Our
findings in chimpanzees implies this variability in response is adaptive
and emphasizes there is not one best response for any given situation,
but rather it depends on the social environment at the time."
Further experiments to investigate reactions to unfair situations are
ongoing at the center in the hopes of understanding why we humans make
the decisions we do. "Identifying a sense of fairness in two closely
related nonhuman primate species implies it could have a long
evolutionary history," Brosnan remarks. The findings will be published
in the February 7 edition of the /Proceedings of The Royal Society B:
Biological Sciences./ --/Sarah Graham/
[Homestead] Chimp sense of justice, reactions,
tvoivozhd, 02/07/2005