>Subject: anonymous cooperation is stable if opting out possible > >Volunteering as Red Queen Mechanism for Cooperation in Public Goods Games > Christoph Hauert, Silvia De Monte, Josef Hofbauer, and Karl Sigmund > Science May 10 2002: 1129-1132. > > >Volunteering as Red Queen Mechanism for Cooperation in Public Goods > Games > > Christoph Hauert,12 Silvia De Monte,13 Josef Hofbauer,1 Karl Sigmund14* > > The evolution of cooperation among nonrelated individuals is one of the fundamental problems in biology and social sciences. > Reciprocal altruism fails to provide a solution if interactions are not repeated often enough or groups are too large. Punishment > and reward can be very effective but require that defectors can be traced and identified. Here we present a simple but effective > mechanism operating under full anonymity. Optional participation can foil exploiters and overcome the social dilemma. In > voluntary public goods interactions, cooperators and defectors will coexist. We show that this result holds under very diverse > assumptions on population structure and adaptation mechanisms, leading usually not to an equilibrium but to an unending cycle of > adjustments (a Red Queen type of evolution). Thus, voluntary participation offers an escape hatch out of some social traps. > Cooperation can subsist in sizable groups even if interactions are not repeated, defectors remain anonymous, players have no > memory, and assortment is purely random. > > 1 Institute for Mathematics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria. > 2 Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4. > 3 Department of Physics, Danish Technical University, DK-2800 Kgs. Lyngby, Denmark. > 4 International Institute for Applied Systems Analysis (IIASA), A-2361 Laxenburg, Austria. > * To whom correspondence should be addressed. E-mail: [EMAIL PROTECTED]