  The rapid succession of discovery of short--duration hard--spectrum GRBs has
led to unprecedented insights into the energetics of the explosion and nature
of the progenitors. Yet short of the detection of a smoking gun, like a burst
of coincident gravitational radiation or a Li-Paczynski mini-supernova, it is
unlikely that a definitive claim can be made for the progenitors. As was the
case with long--duration soft--spectrum GRBs, however, the expectation is that
a systematic study of the hosts and the locations of short GRBs could begin to
yield fundamental clues about their nature. We present the first aggregate
study of the host galaxies of short--duration hard--spectrum GRBs. In
particular, we present the Gemini--North and Keck discovery spectra of the
galaxies that hosted three short GRBs and a moderate--resolution (R~6000)
spectrum of a fourth host. We find that these short--hard GRBs originate in a
variety of low-redshift (z<1) environments that differ substantially from those
of long--soft GRBs, both on individual galaxy scales and on galaxy--cluster
scales. Specifically, three of the bursts are found to be associated with old
and massive galaxies with no current (< 0.1 Msol/hr) or recent star formation.
Two of these galaxies are located within a cluster environment. These
observations support an origin from the merger of compact stellar remnants,
such as double neutron stars of a neutron star--black hole binary. The fourth
event, in contrast, occurred within a dwarf galaxy with a star formation rate
exceeding 0.5 Msol/yr. Therefore, it appears that like supernovae of Type Ia,
the progenitors of short--hard bursts are created in all galaxy types,
suggesting a corresponding class with a wide distribution of delay times
between formation and explosion.
