  The presence of light (m_a ~ 10^-6 ev) scalar fields in the early universe
can modify the cosmology of neutrinos considerably by allowing their masses to
vary on cosmological times. In this paper, we consider the effect of
Planck-suppressed couplings of this scalar to electrons and show that such
couplings can easily make new sterile states thermally inaccessible in the
early universe, preserving the successes of big bang nucleosynthesis
predictions. We consider the circumstances under which these effects give the
proper initial conditions for recently considered models of neutrino dark
energy, and consider limits from tests of the equivalence principle. The
parameters which satisfy cosmological constraints naturally give rise to
interesting signals in terrestrial neutrino oscillation experiments.
