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Fair play

Postal workers and firefighters in the UK have recently walked out in protest at their pay and conditions. Just like humans, monkeys will down tools without hesitation if they feel that they are being ripped off, apparently revealing an innate sense of fair play similar to our own.

The discovery that justice is important to monkeys attracted a lot of attention in the press. The study — carried out at Emory University and published in Nature (18 September 2003) — involved training capuchin monkeys to exchange tokens for food. The monkeys were tested in pairs. As USA Today (18 September 2003) explains, “When pairs of females were both given cucumber in exchange for their tokens, everything was fine. But then one capuchin saw the other receive a grape while it received only cucumber, the seeds of unrest were sown.”

The slighted monkey “often threw away the token, refused to eat the piece of cucumber, or even gave it to the other capuchin,” (The Scotsman, 18 September 2003). According to Sarah Brosnan, one of the researchers, “refusing a food item of any type is very rare behavior in a capuchin,” (USA Today).

Quoted in CBC News (18 September 2003), Brosnan went on to say that “the findings may help explain why people often forgo a reward if they don't perceive it as fair.”

Needless to say, some journalists went to town with their headlines. Perhaps the best one was used by CBC News, who went with “Keep your darn cucumbers: angry monkeys.” Enough said.


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Jones, R. Fair play. Nat Rev Neurosci 4, 939 (2003).

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