Karola Stotz

Senior Lecturer, TWCF Fellow; Philosophy Department; Macquarie University Honorary Associate; Unit for History and Philosophy of Science; University of Sydney

Robustness and Plasticity in Gene Expression: the interplay of stochasticity and downward informational control

The robustness of cell differentiation is produced by distributed information regulated and harnessed by top-down informational control. This happens when the system as a whole influences the causal dynamic of the interaction between the parts at the lower level. Dynamic causation is a strictly an intra-level phenomenon created by the interaction between parts. However, these parts can to some degree constrain the behavior of the whole (bottom-up mediated effects), while at the same time the functionality of the parts is to some degree constrained and selected by the whole (top-down mediated effects). Both Alexei Kurakin and Jean-Jacque Kupiec have advanced related idea. Kupiec proposes a kind of internal process of natural selection that constrains the underlying stochasticity, while Kurakin explains the visual robustness of organism development as the result of a process of molecular self-organisation. Selection, or better variation and selective retention, is of course entailed by self-organisation. However, there exist a wide variety of self-organised systems, all of which are governed by different selection and information processing regimes. Neither selection of the reproductively fittest or alternatively the selection of the physically stable seems to be the kind that allows the emergence of bi-directional causality.