Group Size Effects in Social Evolution

26 Pages Posted: 22 May 2018

See all articles by Jorge Peña

Jorge Peña

Institute for Advanced Study in Toulouse

Georg Nöldeke

University of Basel; University of Basel

Date Written: May 10, 2018

Abstract

How the size of social groups affects the evolution of cooperative behaviors is a classic question in evolutionary biology. Here we investigate group size effects in evolutionary games in which individuals choose whether to cooperate or defect. We find that increasing the group size decreases the proportion of cooperators at both stable and unstable rest points of the replicator dynamics. This implies that larger group sizes can have negative effects (by reducing the amount of cooperation at stable polymorphisms) and positive effects (by enlarging the basin of attraction of more cooperative outcomes) on the evolution of cooperation. These two effects can be simultaneously present in games whose evolutionary dynamics features both stable and unstable rest points, such as public goods games with participation thresholds. Our theory recovers and generalizes previous results and is applicable to a broad variety of social interactions that have been studied in the literature.

Keywords: evolution of cooperation, evolutionary game theory, replicator dynamics, public goods games

JEL Classification: C73, H41

Suggested Citation

Peña, Jorge and Nöldeke, Georg, Group Size Effects in Social Evolution (May 10, 2018). Available at SSRN: https://ssrn.com/abstract=3176517 or http://dx.doi.org/10.2139/ssrn.3176517

Jorge Peña (Contact Author)

Institute for Advanced Study in Toulouse ( email )

31015 Toulouse, Cedex 6
France

Georg Nöldeke

University of Basel ( email )

Peter Merian-Weg 6
Basel, 4002
Switzerland

HOME PAGE: http://sites.google.com/site/georgnoldeke/

University of Basel ( email )

Peter Merian-Weg 6
Basel, 4002
Switzerland

HOME PAGE: http://sites.google.com/site/georgnoldeke/

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