Evolution of ethnocentrism on undirected and directed Barab\'asi-Albert networks

TL;DR

This study uses Monte Carlo simulations to analyze how ethnocentrism evolves in agent-based models on undirected and directed Barabási-Albert networks, revealing that ethnocentric strategies become prevalent regardless of reproduction mode.

Contribution

It extends the Hammond-Axelrod model to complex network topologies, showing the influence of network heterogeneity on ethnocentrism evolution in both asexual and sexual reproduction scenarios.

Findings

Ethnocentrism becomes dominant even without reciprocity or conformity.

Network topology significantly affects the spread of favoritism.

Both undirected and directed BA networks support ethnocentric strategy prevalence.

Abstract

Using Monte Carlo simulations, we study the evolution of contigent cooperation and ethnocentrism in the one-move game. Interactions and reproduction among computational agents are simulated on {\it undirected} and {\it directed} Barab\'asi-Albert (BA) networks. We first replicate the Hammond-Axelrod model of in-group favoritism on a square lattice and then generalize this model on {\it undirected} and {\it directed} BA networks for both asexual and sexual reproduction cases. Our simulations demonstrate that irrespective of the mode of reproduction, ethnocentric strategy becomes common even though cooperation is individually costly and mechanisms such as reciprocity or conformity are absent. Moreover, our results indicate that the spread of favoritism toward similar others highly depends on the network topology and the associated heterogeneity of the studied population.