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The Two Sides of Warfare

An Extended Model of Altruistic Behavior in Ancestral Human Intergroup Conflict

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Abstract

Building on and partially refining previous theoretical work, this paper presents an extended simulation model of ancestral warfare. This model (1) disentangles attack and defense, (2) tries to differentiate more strictly between selfish and altruistic efforts during war, (3) incorporates risk aversion and deterrence, and (4) pays special attention to the role of brutality. Modeling refinements and simulation results yield a differentiated picture of possible evolutionary dynamics. The main observations are: (a) Altruism in this model is more likely to evolve for defenses than for attacks. (b) Risk aversion, deterrence, and the interplay of migration levels and brutality can change evolutionary dynamics substantially. (c) Unexpectedly, one occasional simulation outcome is a dynamically stable state of “tolerated intergroup theft,” raising the question as to whether corresponding patterns also exist in real intergroup conflicts. Finally, possible implications for theories of the coevolution of bellicosity and altruism in humans are discussed.

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Acknowledgments

I thank Max Albert, Charlotte Störmer, Eckart Voland, and Human Nature’s anonymous reviewers for very valuable criticism. Prudent copy-editing by Mary June-el Piper is gratefully acknowledged. This publication represents a component of my doctoral thesis (Dr. rer. nat.) in the Faculty of Biology at the Justus-Liebig-University Giessen, Germany.

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  1. Behavioral and Institutional Economics, JLU Giessen, Licher Strasse 66, 35394, Giessen, Germany

    Hannes Rusch

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  1. Hannes Rusch
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Correspondence to Hannes Rusch.

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Rusch, H. The Two Sides of Warfare. Hum Nat 25, 359–377 (2014). https://doi.org/10.1007/s12110-014-9199-y

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