CRITICALITY AND UNPREDICTABILITY IN MACROEVOLUTION

A recently presented model of large-scale evolution exhibiting self-or ganized criticality is explored from the dynamical point of view. It i s shown that the system approaches the critical state in an anomalous way, with a dynamical exponent z=0. At the same lime, the complexity o f the interactions among species increases, leading to higher unpredic tability. The dynamic evolution is able to generate phylogenetic fract al trees with dimension close to the one obtained from real taxonomy. Some analytic results are presented and an interesting interpretation of the macroevolutionary process is suggested.