  Fry (1996) showed that galaxy bias has the tendency to evolve towards unity,
i.e. in the long run, the galaxy distribution tends to trace that of matter.
Generalizing slightly Fry's reasoning, we show that his conclusion remains
valid in theories of modified gravity (or equivalently, complex clustered dark
energy). This is not surprising: as long as both galaxies and matter are
subject to the same force, dynamics would drive them towards tracing each
other. This holds, for instance, in theories where both galaxies and matter
move on geodesics. This relaxation of bias towards unity is tempered by cosmic
acceleration, however: the bias tends towards unity but does not quite make it,
unless the formation bias were close to unity. Our argument is extended in a
straightforward manner to the case of a stochastic or nonlinear bias. An
important corollary is that dynamical evolution could imprint a scale
dependence on the large scale galaxy bias. This is especially pronounced if
non-standard gravity introduces new scales to the problem: the bias at
different scales relaxes at different rates, the larger scales generally more
slowly and retaining a longer memory of the initial bias. A consistency test of
the current (general relativity + uniform dark energy) paradigm is therefore to
look for departure from a scale independent bias on large scales. A simple way
is to measure the relative bias of different populations of galaxies which are
at different stages of bias relaxation. Lastly, we comment on the possibility
of directly testing the Poisson equation on cosmological scales, as opposed to
indirectly through the growth factor.
