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Walking away from the Haystack: How Contingent Movement Promotes the Evolution of Cooperation

Dr. C. Athena Aktipis
April 16, 2009

Cooperation among group members, coworkers and community members can provide benefits for all involved parties. However, groups of all kinds are plagued by free riders, or individuals who take advantage of cooperative group members by benefiting from being a part of the group without contributing, resulting in a social dilemma or 'tragedy of the commons.' This phenomenon is not unique to humans; free riders can be identified in organisms as simple as bacteria. This has lead to the puzzling question of how cooperation is maintained in social groups of humans and other animals, given higher payoffs for free riding than cooperation. In order to address this question, I simulate individuals who use a simple Walk Away rule to leave groups with many free riders.

As a result of this Walk Away rule, cooperators are able to reap the benefits of being in groups with other cooperators but leave as free riders begin to invade. This often results in a population structure that contains a large number of groups with individuals fluidly moving in and out of groups as the level of cooperation in the groups change. Groups of cooperators are more stable than groups of free riders, which can lead cooperators to have higher overall payoffs than free riders. The simple rule of just 'Walking Away' from groups with free riders does not require complex individual level abilities such as long-term memory, recognition of group members or punishment, suggesting that complex cognitive abilities may not be necessary for cooperation to be promoted.

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Time and location:
Thursday, April 16, 2009
12:00 - 1:00 pm
Center for Social Dynamics and Complexity
ISTB-1, Room 401