Natural selection of memory-one strategies for the iterated prisoner's dilemma.
In the iterated Prisoner's Dilemma, mutually cooperative behavior can become established through Darwinian natural selection. In simulated interactions of stochastic memory-one strategies for the Iterated Prisoner's Dilemma, Nowak and Sigmund discovered that cooperative agents using a Pavlov (Win-Stay Lose-Switch) type strategy eventually dominate a random population. This emergence follows more directly from a deterministic dynamical system based on differential reproductive success or natural selection. When restricted to an environment of memory-one agents interacting in iterated Prisoner's Dilemma games with a 1% noise level, the Pavlov agent is the only cooperative strategy and one of very few others that cannot be invaded by a similar strategy. Pavlov agents are trusting but no suckers. They will exploit weakness but repent if punished for cheating.
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Department of Mathematics, Duke University, Durham, NC 27708, USA. dkraines@math.duke.edu
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D000818:Animals; D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D008433:Mathematics; D008568:Memory; D008957:Models, Genetic; D011157:Population Dynamics; D012641:Selection, Genetic