  We use numerical simulations of large scale structure formation to explore
the cosmological properties of Gamma-Ray Burst (GRB) host galaxies. Among the
different sub-populations found in the simulations, we identify the host
galaxies as the most efficient star-forming objects, i.e. galaxies with high
specific star formation rates. We find that the host candidates are low-mass,
young galaxies with low to moderate star formation rate. These properties are
consistent with those observed in GRB hosts, most of which are sub-luminous,
blue galaxies. Assuming that host candidates are galaxies with high star
formation rates would have given conclusions inconsistent with the
observations. The specific star formation rate, given a galaxy mass, is shown
to increase as the redshift increases. The low mass of the putative hosts makes
them difficult to detect with present day telescopes and the probability
density function of the specific star formation rate is predicted to change
depending on whether or not these galaxies are observed.
