What is it about?

In the real world, when people move from one place to another, they don't always immediately disconnect from their ex-neighbors. In contrast, some long-distance connections across regions persist long after people change places of residence. Inspired by this, we allow individuals to retain a certain number of relationships with their ex-neighbors as they migrate across the network. We found that this co-evolutionary pattern can significantly promote the evolution of cooperation, even if the migration of individuals is completely random, and regardless of whether the retained ex-neighbors are cooperators or defectors. Importantly, tie retention was found to restore the ability of random migrations to induce the outbreak of cooperation. These findings require us to rethink the role of migration, which may be much richer than previously thought.

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Why is it important?

In previous studies, random migration was considered to be detrimental to cooperation. Because it can accelerate the exploitation of cooperators by defectors, or destroy the cluster effect between cooperators. This study challenges this intuitive conclusion and shows that random migration in suitable cases can not only promote cooperation but also induce the outbreak of cooperation.


Tie retention or the generation of long-range connections by migration is an extremely natural and important co-evolutionary pattern that plays an important role in shaping the evolution of strategies.

Dr Zhihu Yang
Xidian University

Read the Original

This page is a summary of: Random migration with tie retention promotes cooperation in the prisoner’s dilemma game, Chaos An Interdisciplinary Journal of Nonlinear Science, April 2023, American Institute of Physics,
DOI: 10.1063/5.0139874.
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