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.
So, there ya go. If the Simianistas start kidnapping people and holding puppet trials on the internet, just remember you were warned here first.