The emergence of cooperative behavior in a competitive world poses something of a puzzle for classical theories of competition, since it appears to be inconsistent with the pursuit of self-interest by individuals. Of course, cooperation among closely related individuals makes sense if it increases the fitness of a specific gene (Hamilton, 1964). But this leaves open the question of why cooperation is often observed among unrelated individuals when “cheating” would yield a higher payoff for any one of them. An ingenious game-theoretic explanation for this case has been put forward by Axelrod and Hamilton (1981) and Axelrod (1984). Imagine a large population of individuals who engage in pairwise interactions. Every time that two individuals meet, they play a “game” whose outcome affects the number of offspring that each of them leaves in the next period. The fittest strategy is the one with the highest reproductive success rate. Even though a strategy is temporarily successful, however, it may eventually become less fit as the frequency of the other strategies in the population changes. In particular, a necessary condition for a strategy’s con-
[1]
Matthew O. Jackson,et al.
The Evolution of Social and Economic Networks
,
2002,
J. Econ. Theory.
[2]
W. Hamilton,et al.
The Evolution of Cooperation
,
1984
.
[3]
D. Levine,et al.
Evolution and Information in a Prisoner's Dilemma Game
,
1998
.
[4]
J. Crow.
Basic concepts in population, quantitative, and evolutionary genetics
,
1986
.
[5]
J M Smith,et al.
Evolution and the theory of games
,
1976
.
[6]
W. Hamilton.
The genetical evolution of social behaviour. I.
,
1964,
Journal of theoretical biology.
[7]
M. Freidlin,et al.
Random Perturbations of Dynamical Systems
,
1984
.