IT’S not love, affection or even blatant self-interest that binds human
societies together. It’s anger. Swiss researchers made the unsettling discovery
while trying to fathom what makes people cooperate.
Traditional explanations, such as kinship and reciprocal altruism, rely on
genetic relationships or self-interest. These work for animals, but fail for
humans because people cooperate with strangers they may never meet again, and
when the pay-off is not obvious.
Such cooperation can be explained if punishment of freeloaders or
“free-riders”—those who do not contribute to a group but benefit from
it—is taken into account. However, in real life, punishment is…
