early age, but with important developmental changes in play. There is a tendency for children to both recognize inequities early in life, but to act selfishly when possible. The envy game shows this beautifully. When another child could receive more, children rejected this option even though it wouldn’t cost them directly: the decider always gets just one candy. Though no one has yet worked out what causes a developmental shift from more to less selfishness, most agree that it is driven by maturation of brain regions guiding self-control, together with social factors that make young children increasingly aware of and sensitive to their own and others’ reputations. Fehr’s studies also show that playing fair is not just about the distribution of resources, but about who gets them. Early in life, children have already carved up the world into those they know and those they don’t. This division drives their thinking and feeling, and in cases like this, their sense of fairness. Young children are well on their way to developing parochial altruism. Fehr’s research, and the majority of studies on the child’s developing sense of fairness, focus on children living in large-scale Western societies. Most of the work on fairness in adults is similarly focused on large scale societies. The precise structure of these societies may directly impact how individuals decide when to share, what commodities enter into the distribution, and whether sharing depends on effort invested, needs, and power. As noted in the last section, those who support an egalitarian society are more likely to feel empathy toward those in pain than those who support a hierarchical society. Individuals who are more empathic are also more altruistic. Hunter-gatherer societies tend to be more egalitarian, and highly cooperative. These differences predict further differences in how those living in small-scale societies, including the hunter-gatherers and subsistence farmers of Africa, Asia, and South America, s