SENSITIVITY TO INITIAL CONDITIONS IN THE BAK-SNEPPEN MODEL OF BIOLOGICAL EVOLUTION

We consider biological evolution as described within the Bak and Snepp en 1993 model. We exhibit, at the self-organized critical state, a pow er-law sensitivity to the initial conditions, calculate the associated exponent, and relate it to the recently introduced nonextensive therm ostatistics. The scenario which here emerges without tuning strongly r eminds of that of the tuned onset of chaos in say logistic-like one-di mensional maps. We also calculate the dynamical exponent z.