Adaptive dynamics of extortion and compliance

Area of Science:

• Evolutionary Game Theory
• Behavioral Economics
• Mathematical Biology

Background:

• Direct reciprocity is a key mechanism for cooperation evolution.
• Zero-determinant strategies allow players to control payoff relationships.
• These strategies can lead to extortion or unconditional cooperation.

Purpose of the Study:

• Investigate the evolutionary dynamics of extortionate and compliant strategies.
• Determine conditions favoring cooperation in iterated social dilemmas.
• Analyze the impact of population size on strategy evolution.

Main Methods:

• Adaptive dynamics modeling.
• Analysis of iterated prisoner's dilemma and snowdrift game.
• Population size as a critical parameter.

Main Results:

• Discovered cyclic dynamics between selfish, extortionate, and compliant strategies.
• Extortion is transient, facilitating a shift towards compliance in large populations.
• Cooperation is most prevalent in large populations, approaching the social optimum.

Conclusions:

• Generosity, not dominance, succeeds in large populations for iterated social dilemmas.
• Population size critically influences the prevalence of cooperation.
• Findings extend beyond the prisoner's dilemma to other social dilemmas.