Core-Periphery Segregation in Evolving Prisoner's Dilemma Networks

TL;DR

This study investigates how evolving social networks in Prisoner's Dilemma experiments develop core-periphery structures that promote cooperation, showing that strategic behaviors lead to dense cooperative cores and isolated defectors, thus enhancing social capital.

Contribution

It reveals the role of core-periphery segregation and specific strategies in the self-organization of cooperative networks during evolution.

Findings

Cooperative networks form dense cores that isolate defectors.

Quit-for-Tat and Roving strategies drive core-periphery segregation.

Cooperators in the core earn higher payoffs than defectors.

Abstract

Dense cooperative networks are an essential element of social capital for a prosperous society. These networks enable individuals to overcome collective action dilemmas by enhancing trust. In many biological and social settings, network structures evolve endogenously as agents exit relationships and build new ones. However, the process by which evolutionary dynamics lead to self-organization of dense cooperative networks has not been explored. Our large group prisoner's dilemma experiments with exit and partner choice options show that core-periphery segregation of cooperators and defectors drives the emergence of cooperation. Cooperators' Quit-for-Tat and defectors' Roving strategy lead to a highly asymmetric core and periphery structure. Densely connected to each other, cooperators successfully isolate defectors and earn larger payoffs than defectors. Our analysis of the topological characteristics of evolving networks illuminates how social capital is generated.