Environmental variability promotes the evolution of cooperation among geographically dispersed groups on dynamic networks

TL;DR

This study demonstrates that environmental variability, especially regional shifts, significantly promotes the evolution of cooperation among human groups on dynamic networks, highlighting the importance of network coevolution.

Contribution

It introduces three stochastic models of environmental variability and shows how regional variability fosters cooperation and network coevolution, offering new insights into human evolutionary dynamics.

Findings

Regional variability strongly promotes cooperation

Universal variability has a weaker effect on cooperation

Co-evolution of cooperation and network structure is essential

Abstract

The evolutionary process that led to the emergence of modern human behaviors during the Middle Stone Age in Africa remains enigmatic. While various hypotheses have been proposed, we offer a new perspective that integrates the variability selection hypothesis (VSH) with the evolution of cooperation among human groups. The VSH suggests that human adaptability to fluctuating environments was a primary force driving the development of key evolutionary traits. However, the mechanisms by which environmental variability (EV) influenced human evolution, particularly the emergence of large-scale and complex cooperative behaviors, are not yet fully understood. To explore the connection between intensified EV and the evolution of intergroup cooperation, we analyzed three stochastic models of EV: (i) Regional Variability (RV), where resource-rich areas shift while overall resource levels remain stable; (ii) Universal Variability (UV), where overall resource levels fluctuate but resource-rich areas remain stable; and (iii) Combined Variability (CV), where both resource-rich areas shift and overall resource levels fluctuate. Our results show that RV strongly promotes cooperation, while UV has a comparatively weaker effect. Additionally, our findings indicate that the coevolution of cooperation and network structures is crucial for EVs to effectively promote cooperation. This study proposes a novel causal link between EV and the evolution of cooperation, potentially setting a new direction for both theoretical and empirical research in this field.