  The nucleon axial charge is calculated as a function of the pion mass in full
QCD. Using domain wall valence quarks and improved staggered sea quarks, we
present the first calculation with pion masses as light as 354 MeV and volumes
as large as (3.5 fm)^3. We show that finite volume effects are small for our
volumes and that a constrained fit based on finite volume chiral perturbation
theory agrees with experiment within 7% statistical errors.
