A major goal of investigating how cooperative norms in societal settings have been established is a better understanding of how to promote cooperativ… - Robert Axelrod

The theory of biological evolution is based on the struggle for life and the survival of the fittest. Yet cooperation is common between members of the same species and even between members of different species. Before about 1960, accounts of the evolutionary process largely dismissed cooperative phenomena as not requiring special attention. This dismissal followed from a misreading of theory that assigned most adaptation to selection at the level of populations or whole species. As a result of such misreading, cooperation was always considered adaptive. Recent reviews of the evolutionary process, however, have shown no sound basis for viewing selection as being based upon benefits to whole groups. Quite the contrary. At the level of a species or a population, the processes of selection are weak. The original individualistic emphasis of Darwin's theory is more valid.

Tournament studies, ecological simulation, and theoretical analysis demonstrate: (1) A generous version of tit for tat is a highly effective strategy when the players it meets have not adapted to noise; (2) If the other players have adapted to noise, a contrite version of tit for tat is even more effective at quickly restoring mutual cooperation without the risk of exploitation; (3) Pavlov is not robust.

In the future it would be good to use these conceptual and statistical developments to answer some new questions suggested by the model. For example, the dynamics we have seen in the tribute model suggest the following interesting questions:
a. What are the minimal conditions for a new actor to emerge?
b. What tends to promote such emergence?
c. How are the dynamics affected by the number of elementary actors?
d. What can lead to collapse of an aggregate actor?
e. How can new actors grow in the shadow of established actors?