Policing institutions substitute for kin-based altruism where populations are genetically diverse.

Evidence

If freeriding—the act of receiving benefits without reciprocating—incurs a reliably hefty punitive cost, potential freeriders may restrain their selfish urges. Punishment of selfish acts is an effective strategy that stabilizes cooperation, but it pushes the problem further back: monitoring and punishing freeriders itself can be costly, which means that individuals would rather see someone else punish selfish individuals and enjoy the fruits of cooperative groups. It creates opportunities for people to freeride on their punishment duties. One solution to this problem, of course, is third-party punishment—that is, policing institutions. A study done in Switzerland, for example, found that in cantons with genetically homogenous populations, where kinship ties are strong, people rely on the police less. However, in cantons with greater genetic diversity, reliance on police increases, exactly as would be expected if policing institutions were designed to enforce cooperation among strangers. — Norenzayan, Ara, Big gods - how religion transformed…, 35

Categorization

• XREF: Supports the Big God mechanism: external third-party punishment institutions, including supernatural ones, emerge where kin ties cannot enforce cooperation among strangers.
• SHARE: The Swiss canton police-reliance finding (genetic homogeneity vs. diversity) is a narrow, precise data point a specific scholar of institutional evolution would relish.