Cooperation maintained by fitness adjustment

Christine Taylor, Janet Chen, Yoh Iwasa

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Questions: Can cooperation be enhanced if players whose performance is higher than the mean are forced to pay an additional cost in each generation? Mathematical methods: Analysis of replicator dynamics with mutation. The ESS distribution of cooperation level is obtained. Key assumptions: Players engage in a cooperative dilemma game, and at the end of each generation those whose performance is higher than the mean are forced to pay an additional cost. Conclusions: Without mutation, the entire population eventually conforms to a single cooperation level determined by the initial composition of the population. With mutation, there is an equilibrium distribution of cooperation, which has a peak at an intermediate level of cooperation. Whether it is institutionalized such as tax or just a social custom, fitness adjustment based ultimately on people's 'envy' is able to maintain cooperation.

Original languageEnglish (US)
Pages (from-to)1023-1041
Number of pages19
JournalEvolutionary Ecology Research
Issue number6
StatePublished - Oct 2007

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics


  • Distribution of cooperation level
  • Envy
  • Evolution of cooperation
  • Fitness adjustment
  • Punishment


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