Agradecimientos:
We acknowledge financial support from Ministerio de Ciencia y Tecnología (Spain) through grants BFM2003-07749-C05-01 (AS) and BFM2003-0180 (JAC).
The fact that humans cooperate with non-kin in large groups, or with people they will never meet again, is a long-standing
evolutionary puzzle. Altruism, the capacity to perform costly acts that confer benefits on others, is at the core of cooperative
behaviThe fact that humans cooperate with non-kin in large groups, or with people they will never meet again, is a long-standing
evolutionary puzzle. Altruism, the capacity to perform costly acts that confer benefits on others, is at the core of cooperative
behavior. Behavioral experiments show that humans have a predisposition to cooperate with others and to punish non-cooperators
at personal cost (so-called strong reciprocity) which, according to standard evolutionary game theory arguments, cannot arise from
selection acting on individuals. This has led to the suggestion of group and cultural selection as the only mechanisms that can
explain the evolutionary origin of human altruism. We introduce an agent-based model inspired on the Ultimatum Game, that
allows us to go beyond the limitations of standard evolutionary game theory and show that individual selection can indeed give rise
to strong reciprocity. Our results are consistent with the existence of neural correlates of fairness and in good agreement with
observations on humans and monkeys.[+][-]
