  Top-down causation has been suggested to occur at all scales of biological
organization as a mechanism for explaining the hierarchy of structure and
causation in living systems. Here we propose that a transition from bottom-up
to top-down causation -- mediated by a reversal in the flow of information from
lower to higher levels of organization, to that from higher to lower levels of
organization -- is a driving force for most major evolutionary transitions. We
suggest that many major evolutionary transitions might therefore be marked by a
transition in causal structure. We use logistic growth as a toy model for
demonstrating how such a transition can drive the emergence of collective
behavior in replicative systems. We then outline how this scenario may have
played out in those major evolutionary transitions in which new, higher levels
of organization emerged, and propose possible methods via which our hypothesis
might be tested.
