Models of development

Abstract

Ciliberti et al.(2007a, b), culminating a long series of papers, apply the spinglass model from statistical physics to organisimal development in an evolutionary context. We summarize their results and look at some of the less obvious topological implications – in particular the mapping of disjoint directed homotopy classes of phenotype paths into interaction matrix space. We then extend the approach by applying a cognitive paradigm for gene expression first developed in Wallace and Wallace (2008). Analogs to phase change arguments for physical systems generate punctuated equilibrium evolutionary transitions in a ‘highly natural’ manner, even for the spinglass treatment, and a hierarchical extension permits incorporation of epigenetic effects as a kind of tunable catalysis.