On the Relationship between the Duration of an Encounter and the Evolution of Cooperation in the Iterated Prisoner's Dilemma

Evolutionary programming experiments are conducted to examine the relationship between the durations of encounters and the evolution of cooperative behavior in the iterated prisoner's dilemma. A population of behavioral strategies represented by finite-state machines is evolved over successive generations, with selection made on the basis of individual fitness. Each finite-state machine is given an additional evolvable parameter corresponding to the maximum number of moves it will execute in any encounter. A series of Monte Carlo trials indicates distinct relationships between encounter length and cooperation; however, no causal relationship can be positively identified.