Mediator Evolution: a general scenario for the origin of dynamical hierarchies

A general scenario is proposed to understand the evolutionary transitions that lead to the emergence of higher level systems through the assembly of independent components. First, multilevel emergence is reviewed in general as the result of variation and selective retention of assemblies. It is emphasized that when the components are dissipative (e.g. living systems) the process is complicated by the on-going competition for scarce resources between the agents. While there is a selective pressure to achieve synergy, and thus avoid conflict, competition remains potentially present, leading to the free rider problem. To tackle this problem, a control must evolve to suppress conflict. This can be achieved by an exploiter (e.g. parasite) evolving to become a cultivator of the collective. The “exploiter” does not need to be an external invader, but can be a distributed mode of interaction or “aspect system” of the collective, that may co-opt external support. The detailed scenario is as follows: 1) a collective of agents interacts, constituting an interaction medium; 2) the medium coordinates the interactions, becoming a conflict mediator; 3) the mediator establishes active control over the agents, becoming a goal-directed manager. These proposed stages of an evolutionary transition are used to analyse a variety of concrete examples, including physical selforganization, spatial partioning of competing agents in biology, and the evolution