SELF-ORGANIZED CRITICALITY IN LIVING SYSTEMS

We suggest that ensembles of self-replicating entities such as biologi cal systems naturally evolve to a self-organized critical state in whi ch fluctuations, as well as waiting times between phase transitions (' 'epochs''),are distributed according to a 1/f(alpha) power law. Such d istributions can explain observed frequency distributions in extinctio n events as well as fractal population structures, and support the pun ctuated equilibrium picture of evolution. We demonstrate these concept s by analyzing a population of coexisting self-replicating strings (se gments of computer code) subject to mutation and survival of the fitte st, which constitutes an artificial living system.