Before revision:  In the classical prisoner's dilemma, evolutionary game dynamics predict that all individuals evolve to 'defect ,' but when the rate of cooperation within a population is directly linked to the rate of spread of the disease, cooperation evolves under certain conditions.
After revision:  In the classical prisoner's dilemma, evolutionary game dynamics predict that all individuals evolve to 'defect .' We have discovered that when the rate of cooperation within a population is directly linked to the rate of spread of the disease, cooperation evolves under certain conditions.