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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Numerical Analysis Seminars: The evolution of cooperation in a Darwinian world

6 October 2000 00:00 in CM105

"Observations of cooperative behaviour among unrelated individuals (e.g. food sharing, grooming, predator inspection) are of great interest to evolutionary biologists, not least because such altruism appears open to abuse (receiving help without giving it). The classical Prisoners' Dilemma game, in which players repeatedly choose to cooperate (C) or defect (D), remains the central tool for identifying the types of cooperative strategy that might evolve in the natural world, but it is often criticised by empiricists. For instance, in the real world individuals can vary their investments in partners, so the option of co-operation is rarely all or nothing. Similarly, defection is rarely more than the passive strategy of not cooperating.

In this talk, I present a simple model of biological trade which is consistent with the Prisoners' Dilemma model, but which allows individuals to vary their cooperative investments. In reformulating the model in this way, it is clear that whole new ways of cheating are possible, such undercutting your partner's investment. Despite these potentially erosive forces, I show that cooperation can still thrive under these conditions, and that it is likely to do so by strategies which both build up trust in partners and which react quantitatively to partners that short-change them.

In the final section of my talk I present the results of more recent analyses in which I demonstrate: (i) that cooperative interactions can still occur despite wide variation in the frequency of needing help, and (ii) that individuals who can't (rather than won't!) reciprocate are likely to play an important role in enhancing the evolutionary stability of cooperation."

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