  We report an analysis of the impressive new lattice simulation results for
octet baryon masses in 2+1-flavor QCD. The analysis is based on a low order
expansion about the chiral SU(3) limit in which the symmetry breaking arises
from terms linear in the quark masses plus the variation of the Goldstone boson
masses in the leading chiral loops. The baryon masses evaluated at the physical
light quark masses are in remarkable agreement with the experimental values,
with a model dependence considerably smaller than the rather small statistical
uncertainty. From the mass formulae one can evaluate the sigma commutators for
all octet baryons. This yields an accurate value for the pion-nucleon sigma
commutator. It also yields the first determination of the strangeness sigma
term based on 2+1-flavor lattice QCD and, in general, the sigma commutators
provide a resolution to the difficult issue of fine-tuning the strange quark
mass.
