Cheikbossian, GuillaumeORCID: https://orcid.org/0000-0002-7461-1467 and Peña, JorgeORCID: https://orcid.org/0000-0002-4137-1823 (2026) Evolutionary branching of social preferences in a public good provision game. TSE Working Paper, n. 26-1737, Toulouse

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Abstract

We study the evolution of other-regarding preferences in a public goods game
where the production function exhibits varying degrees of complementarity between
individual efforts. Individuals are rational agents who play a Nash equilibrium, but
differ in the weight they assign to others’ payoffs, capturing varying degrees of prosocial
or anti-social preferences. This preference trait evolves through payoff-based
biased social learning, modeled within an adaptive dynamics framework. Because
material payoffs induced by the equilibrium contributions may be non-concave in the
preference parameter, evolutionary branching can arise. We show that monomorphic
populations are evolutionarily stable only when complementarity between individual
efforts is sufficiently strong, in which case preferences converge toward either prosociality
or anti-sociality depending on the nature of strategic interactions between
players. By contrast, when contributions are highly substitutable, monomorphic populations
can become unstable, giving rise to polymorphic populations in which multiple
preference types coexist. These results highlight how the structure of the public
goods environment shapes the evolution and diversity of other-regarding motivations
in culturally evolving populations.