Conceptual Capacity to Categorize and the Evolution of Altruism

The conceptual capacity to categorize and consequently the ability to approve or reprove the one's and other's behavior allows the appearance of individuals with a new type of cooperative behavior that we have called "Assessor". The Assessor individual, if the partner behaves in a selfish way, reproves and penalizes this behavior changing his initial cooperation into defect. The reprobation permits that Assessor individuals, through simple observation, inhibit their altruistic behavior towards individuals whose selfish behavior has already been reproved, without having to interact with them. The evolutionary properties of Assessor behavior are analysed using the model of the iterated prisoner's dilemma where Assessor individuals compete with "always defect" individuals. The results are compared with those obtained, in the same circumstances, by other cooperative behaviors such as "always cooperate", "Tit-for-Tat" and "Observer-Tit-For-Tat". It is shown that in all situations Assessor is evolutionarily stronger than Tit-for-Tat when both face ALL D. It is also advantageous with respect to Observer-Tit-For-Tat in those situations that favor the evolution of reciprocal altruism "Tit-for Tat".Copyright 1998 Academic Press Limited