(ATLANTA) -- With our extensive systems of governance and such global cooperative networks as the United Nations and the World Health Organization, humans are expert cooperators when compared with other animals or even relative primates, such as chimpanzees and capuchin monkeys.
But how much of this cooperation depends on our ability to speak? Apparently more than you'd believe. That is the take-away message of a study published Monday in the Proceedings of the National Academy of Sciences.
At the core of the study was a cooperative-rewards game in which participants -- be they man, monkey or chimp -- had to work in pairs. The game required participants to cooperate to get the biggest payout -- quarters and dollars for the humans, tasty fruit for the primates. While there was a less-than-ideal cooperation scenario that gave each partner in a pair a quarter, "winning the game" meant figuring out which scenario offered a dollar reward at each round.
When humans were not told the rules of the game and had to figure things out nonverbally, the way their chimp and capuchin monkey primate counterparts had to, human cooperation did not far outperform that of the other primates.
"Normally, we expect to see 100 percent cooperation with humans when they know the rules of the game. When we had them go in blind, only five pairs out of 26 developed the best scenarios of cooperation. That's only 20 percent," said lead author Sarah Brosnan, a psychologist at the Language Research Center at Georgia State University.
Humans still outperformed the other primates, who were chosen because they were notoriously cooperative species, but the extent to which the lack of language handicapped the human pairs was surprising, Brosnan noted.
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