This essay describes a model of evolution in a changing environment based on Markov chains. A diverse society is more likely to survive adverse changes than a more uniform society well adapted to the current environment. Diversity among the members of the society does not depend on chance. It results from their experience in a history of successful adaptations to challenging conditions. Even those less well adapted to present conditions can survive and revive facing adverse changes better than those adapted to what had been long lasting existing conditions. JEL O Economic Development, Technological Change and Growth