[monkeywire] Experiment Proves Existence of Monkey Justice
ahewins at mac.com
Sun Sep 23 10:25:19 EDT 2007
BBC NEWS / SCIENCE/NATURE
Wednesday, 17 September, 2003, 18:39 GMT 19:39 UK
Monkeys show sense of justice
By Dr David Whitehouse
BBC News Online science editor
Monkeys have a sense of justice. They will protest if they see
another monkey get paid more for the same task.
Monkeys display sense of justice Researchers taught brown capuchin
monkeys to swap tokens for food. Usually they were happy to exchange
this "money" for cucumber.
But if they saw another monkey getting a grape - a more-liked food -
they took offence. Some refused to work, others took the food and
refused to eat it.
Scientists say this work suggests that human's sense of justice is
inherited and not a social construct.
Differential reward experiment
The research was carried out at Emory University in the US, by Sarah
Brosnan and Frans de Waal, and is reported in the journal Nature.
"I'm extremely interested in the evolution of cooperation," Sarah
Brosnan told BBC News Online.
"One of the most interesting areas is the recent suggestion that
human cooperation is made more effective by a sense of fairness."
She wanted to find out if the human sense of fairness is an evolved
behaviour or a cultural construct - the result of society's rules.
So she and her colleagues devised an experiment using capuchin monkeys.
Experiment, Nature/Emory University Sarah Brosnan said: "I chose the
capuchin because they are very cooperative, and because they come
from a very tolerant society.
"We designed a very simple experiment to see whether or not they
react to differential rewards and efforts."
Capuchins like cucumber, but they like grapes even more. So a system
was devised whereby pairs of capuchins were treated differently after
completing the same task.
"They had never before been in any sort of situation where they were
differentially rewarded," she said.
"We put pairs of capuchins side by side and one of them would get the
cucumber as a reward for a task."
The partner sometimes got the same food reward but on other occasions
got a grape, sometimes without even having to work for it."
'A highly unusual behaviour'
The response was dramatic, the researchers said.
"We were looking for a very objective reaction and we got one. They
typically refused the task they were set," Sarah Brosnan said.
"The other half of the time they would complete the task but wouldn't
take the reward. That is a highly unusual behaviour.
"Sometimes they ignored the reward, sometimes they took it and threw
it down," she added.
Nature/Emory University The researchers were not surprised that the
monkeys showed a sense of fairness, but they were taken aback that
they would turn down an otherwise acceptable reward.
"They never showed a reaction against their partner, they never
blamed them," Sarah Brosnan said.
Commenting on the results, experts in the subject told BBC News
Online that the idea of a long evolutionary history for a sense of
fairness was an exciting one.
However, they added that they would like to see more research
involving more than just the five subjects tested in the Nature study.
So does our instinctive feeling of fairness predate our species?
"It may well," Sarah Brosnan said, and further experiments are
planned to see how extensive a sense of justice in the animal world is.
"We are currently repeating the study on chimpanzees, a great ape
species, to learn something more about the evolutionary development
of the sense of fairness.
"I suspect that there are other non-primate species with tolerant
societies that will show the same behaviour."
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