  Cooperation and self-organized criticality are two main keywords in current
studies of evolution. We propose a generalized Bak-Sneppen model and provide a
natural mechanism which accounts for both phenomena simultaneously. We use the
prisoner's dilemma games to mimic the interactions among the members of the
population. Each member is identified by its cooperation probability, and its
fitness is given by the payoffs from neighbors. The least fit member with the
minimum payoff is replaced by a new member with a random cooperation
probability. When the neighbors of the least fit member are also replaced with
a non-zero probability, a strong cooperation emerges. The Bak-Sneppen process
builds a self-organized structure so that the cooperation can emerge even in
the parameter region where a uniform or random population decreases the number
of cooperators. The emergence of cooperation is due to the same dynamical
correlation which leads to self-organized criticality in replacement
activities.
