Influence of Local Interactions in the Bak-Sneppen Model and Economic   Applications
  In the present work we extend the Bak-Sneppen model for biological evolution by introducing local interactions between species. This ``environmental'' perturbation can modify the intrinsic fitness of each element of the ecology, leading to higher survival probability, even for the less fit. While the system still self-organizes toward a critical state, the distribution of fitness broadens, losing the classical step-function shape. A possible application in economics is discussed, where firms are represented like evolving species linked by mutual interests. 
M. Bartolozzi, D. B. Leinweber and A. W. Thomas