Interaction, uncertainty, and the evolution of complexity

The evolution of complexity is investigated in the context of an `iterated prisoner's dilemma' (IPD) co-evolutionary/game-theoretic ecology, populated by strategies determined by variable length genotypes. New evidence is found to support the dual hypotheses that both uncertainty, and interaction (by way of population stability), foster the evolution of progressively more complex entities. It is also argued that during periods of major evolutionary upheaval, complex entities suffer disproportionately and become less abundant in the population. The research is presented as an elaboration of the general principle that there is complexity in an organism by virtue of complexity in the environment, and has implications both for deepening understanding of the nature of biological evolution and for guiding the progress of artificial evolution.