Many-strategy games in groups with relatives and the evolution of coordinated cooperation

Area of Science:

• Evolutionary Game Theory
• Behavioral Ecology
• Social Evolution

Background:

• Human cooperation occurs in groups with varying genetic relatedness.
• Kin selection explains cooperation's origins but is complex with non-linear benefits.
• Modeling relatedness is challenging when cooperation benefits scale with group size.

Purpose of the Study:

• To develop a direct fitness method for analyzing kin selection in n-player interactions.
• To rigorously account for non-additive fitness effects (synergy) in cooperative groups.
• To model discrete strategies and group formation with genetic homophily.

Main Methods:

• Utilized a direct fitness method for n-player interactions with m discrete strategies.
• Employed a genetically homophilic group-formation model to derive higher-order relatedness coefficients.
• Derived analytical expressions for dynamics, solvable numerically for specific group sizes and strategies.

Main Results:

• Coordinated cooperation, particularly with cheap talk and sigmoidal public good benefits, is favored by kin selection.
• Cooperation among strangers requires maintained homophily or self-interest to resist 'liars'.
• The model successfully accounts for non-additive fitness effects and synergy among relatives.

Conclusions:

• The direct fitness method provides a robust framework for studying kin selection with non-additive benefits.
• Kin selection plays a significant role in maintaining cooperation, especially in structured populations.
• Understanding group dynamics and individual incentives is key for sustained cooperation beyond kin groups.