Metanorms generate stable yet adaptable normative social order in a politically decentralized society

Norms are essential for social stability but can hinder adaptability in changing environments. Yet human societies have found ways to modify existing norms or create new ones in response to novel challenges. This paper proposes a framework for understanding adaptive norm evolution. First, drawing on a theory of legal order, we posit that societies balance normative stability and adaptability through metanorms-rules that govern the process by which norms are interpreted, changed and enforced. Second, we test this idea in the context of customary dispute resolution by elders among the Turkana, a pastoralist society in Kenya. Based on vignette experiments with 369 participants, we found that community members were significantly more willing to enforce decisions when elders aligned their conduct with metanorms. Elders are constrained in their ability to alter long-standing customs, but by following metanorms, they can create new rules for novel situations. These findings support our proposed mechanism: in the absence of centralized authority, metanorms governing normative institutions allow for adaptive norm change while preserving cultural continuity. We conclude by suggesting that group-level selection acts on cultural variation in metanorms, shaping the evolvability of normative systems and enabling societies to sustain adaptive legal order without coercive centralized power. This article is part of the theme issue 'Transforming cultural evolution research and its application to global futures'.