Biological Development and Evolution, Complexity and Self-organization in

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Definition of the Subject

Much work over the past half‐century in developmental and evolutionary biology has focused on a subset of an organism's components, itsgenes. The hierarchical regulatory relationships among genes have been a major emphasis in studies indevelopment, while the variation of genes has played a corresponding role in evolutionary studies. In the past decade, however, investigators haveincreasingly considered the part played by physical and dynamical properties of cells and tissues, and their molecular components, in producing biologicalcharacteristics over the course of ontogeny and phylogeny. Living cells and tissues encompass numerous interpenetrating multicomponent systems in whichdynamical interactions among intracellular gene products, metabolites, ions, etc., and interactions between cells, directly via theiradhesive surfaces, or indirectly via secreted extracellular matrix (ECM) molecules or diffusible signaling molecules