Noise driven emergence of cooperative behavior

TL;DR

This paper demonstrates that cooperative behavior can emerge through stochastic effects in evolutionary dynamics, specifically when cooperators increase habitat capacity, leading to higher genetic drift and fixation probabilities, independent of deterministic advantages.

Contribution

It introduces a stochastic model showing cooperation can arise from increased habitat capacity and genetic drift, without relying on deterministic selection advantages.

Findings

Cooperative behaviors increase habitat capacity.

Increased habitat capacity enhances genetic drift against non-cooperators.

Cooperation dominates when habitat benefits outweigh selection pressure.

Abstract

Cooperative behaviors are defined as the production of common goods benefitting all members of the community at the producer's cost. They could seem to be in contradiction with natural selection, as non-cooperators have an increased fitness compared to cooperators. Understanding the emergence of cooperation has necessitated the development of concepts and models (inclusive fitness, multilevel selection, ...) attributing deterministic advantages to this behavior. In contrast to these models, we show here that cooperative behaviors can emerge by taking into account the stochastic nature of evolutionary dynamics : when cooperative behaviors increase the carrying capacity of the habitat, they also increase the genetic drift against non-cooperators. Using the Wright-Fisher models of population genetics, we compute exactly this increased genetic drift and its consequences on the fixation probability of both types of individuals. This computation leads to a simple criterion: cooperative behavior dominates when the relative increase in carrying capacity of the habitat caused by cooperators is higher than the selection pressure against them. This is a purely stochastic effect with no deterministic interpretation.