Altruism can proliferate through group/kin selection despite high random gene flow

TL;DR

This paper demonstrates that complex group interactions and random migration do not prevent the spread of altruism, challenging previous beliefs that migration hinders altruistic behavior in structured populations.

Contribution

It introduces a comprehensive framework combining group and gene perspectives, extending Hamilton's rule to broader conditions for altruism proliferation.

Findings

Strong altruism can spread when rare under realistic conditions.

Contingent altruism persists despite high migration.

Extensions of Hamilton's rule are applicable broadly.

Abstract

The ways in which natural selection can allow the proliferation of cooperative behavior have long been seen as a central problem in evolutionary biology. Most of the literature has focused on interactions between pairs of individuals and on linear public goods games. This emphasis led to the conclusion that even modest levels of migration would pose a serious problem to the spread of altruism in group structured populations. Here we challenge this conclusion, by analyzing evolution in a framework which allows for complex group interactions and random migration among groups. We conclude that contingent forms of strong altruism can spread when rare under realistic group sizes and levels of migration. Our analysis combines group-centric and gene-centric perspectives, allows for arbitrary strength of selection, and leads to extensions of Hamilton's rule for the spread of altruistic alleles, applicable under broad conditions.