Moderate immigration may promote a peak of cooperation among natives

TL;DR

This study demonstrates that moderate immigration of cooperative individuals can significantly enhance native cooperation in public goods games, with a small fraction of efficient immigrant cooperators acting as catalysts for widespread cooperation.

Contribution

It introduces a model showing how efficient cooperative immigrants can trigger and maximize native cooperation at moderate immigration rates.

Findings

Native cooperation peaks at moderate immigration levels.

A small fraction of cooperative immigrants can induce widespread cooperation.

Cooperative immigrants serve as nucleation centers for cooperative clusters.

Abstract

In a world of hardening borders, nations may deprive themselves of enjoying the benefits of cooperative immigrants. Here, we analyze the effect of efficient cooperative immigrants on a population playing public goods games. We considered a population structured on a square lattice with individuals playing public goods games with their neighbors. The demographics are determined by stochastic birth, death, and migration. The strategies spread through imitation dynamics. Our model shows that cooperation among natives can emerge due to social contagion of good role-model agents that can provide better quality public goods. Only a small fraction of efficient cooperators, among immigrants, is enough to trigger cooperation across the native population. We see that native cooperation achieves its peak at moderate values of immigration rate. Such efficient immigrant cooperators act as nucleation centers for the growth of cooperative clusters, that eventually dominate defection.