Monkeys, Cucumbers and Grapes

Son Thomas mentioned to me, in the context of monkeys becoming angry (a continuation of discussions about “going apeshit”) a clip on Youtube about an experiment.

It is a great little clip that illustrates that even monkeys can have strong negative feelings about perceived unfairness.

The clip can be seen by clicking on:

http://www.youtube.com/watch?v=3XXQMDGErL0

The clip is well worth watching.

Called 'The Fairness Study', it was originally conducted in 2003 at Emory University in the US, by Sarah Brosnan and Frans de Waal. According to Sarah Brosnan, "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.

To test this question, she and her colleagues devised an experiment using capuchin monkeys:  "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."

The response was dramatic, the researchers said. According to Sarah "We were looking for a very objective reaction and we got one. They typically refused the task they were set. 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.”

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.

Frans de Waal, a primatologist and Emory University professor who had been involved with Sarah Brosnan in the 2003 experiment, performed it again in 2012 and taped the results. That is the video that is linked above.

According to de Waal, the study has, since 2003, been repeated with dogs, birds and chimpanzees. 

If both monkeys get cucumber as a reward, according to de Waal, they are happy to repeat the task up to 25 times. 'But if you give one grapes, which is a far better food, then you create inequity between them. So, this is basically the Wall Street protest that you see here. “

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