Signalling boosts the evolution of cooperation in repeated group interactions

TL;DR

This paper uses an evolutionary game model to compare how signalling and direct reciprocity promote cooperation, finding signalling alone often yields higher cooperation levels and is more robust, explaining its widespread presence.

Contribution

It jointly analyzes signalling and direct reciprocity mechanisms, revealing their interaction and conditions favoring each, with insights into their evolutionary robustness and prevalence.

Findings

Signalling alone leads to higher cooperation than combined mechanisms.

Signalling is more robust and evolves even when costly.

Direct reciprocity is less favored in the presence of signalling.

Abstract

Many biological and social systems show significant levels of collective action. Several cooperation mechanisms have been proposed, yet they have been mostly studied independently. Among these, direct reciprocity supports cooperation on the basis of repeated interactions among individuals. Signals and quorum dynamics may also drive cooperation. Here, we resort to an evolutionary game theoretical model to jointly analyse these two mechanisms and study the conditions in which evolution selects for direct reciprocity, signalling, or their combination. We show that signalling alone leads to higher levels of cooperation than when combined with reciprocity, while offering additional robustness against errors. Specifically, successful strategies in the realm of direct reciprocity are often not selected in the presence of signalling, and memory of past interactions is only exploited opportunistically in case of earlier coordination failure. Differently, signalling always evolves, even when costly. In the light of these results, it may be easier to understand why direct reciprocity has been observed only in a limited number of cases among non-humans, whereas signalling is widespread at all levels of complexity.