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

This repository contains all the source code utilized in the following study:

• Title: Environmental variability promotes the evolution of cooperation among geographically dispersed groups on dynamic networks
• Author: Masaaki Inaba, Eizo Akiyama
• Published: Under review
• Journal: Preprint (arXiv)
• DOI: https://doi.org/10.48550/arXiv.2411.12348
• Citation: Inaba, M., & Akiyama, E. (2024). Environmental variability promotes the evolution of cooperation among geographically dispersed groups on dynamic networks. arXiv preprint arXiv:2411.12348.

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.