Life may not be fair, but humans have a strong bias for fairness. In experiments, humans will generally reject or punish a partner who offers noticeably less than half of a shared reward, even if they wind up empty-handed. Chimps, it turns out, are not so picky and will (rationally, an economist might add) take whatever they can get, according to an October 2007 Science paper. So what could explain this difference between our closest living relatives and us?
The answer may lie in the social relationships that influence so many of our actions. Recent studies of primate fairness seem to contradict one another—unless you consider who exactly is cheating whom.