ARE CRITICAL PHENOMENA RELEVANT TO LARGE-SCALE EVOLUTION

Recent theoretical studies, based on the theory of self-organized crit ical systems, seem to suggest that the dynamical patterns of macroevol ution could belong to such class of critical phenomena. Two basic appr oaches have been proposed: the Kauffman-Johnsen model (based on the us e of coupled fitness landscapes) and the Bak-Sneppen model. Both are r eviewed here. These models are oversimplified pictures of biological e volution, but the (possible) validity of them is based on the concept of universality, i.e. that apparently very different systems sharing s ome few common properties should also behave in a very similar way. In this paper we explore the current evidence from the fossil record, sh owing that some properties that are suggestive of critical dynamics wo uld also be the result of random phenomema. Some general properties of the large-scale pattern of evolution, which should be reproduced by t hese models, are discussed.