The near-infrared (NIR) luminosity of long-duration GRB host galaxies as a function of redshift, compared to star-forming galaxies (gray). The NIR luminosity can be used as a stellar mass proxy: the horizontal blue curves indicate equivalent stellar masses. GRBs sample galaxies of all masses and redshifts, but rarely occur in the most luminous galaxies, especially at low redshift (z < 1.5). This is probably because GRBs are strongly suppressed in metal-rich galaxies, leading to a soft “upper limit” on the host stellar mass that increases with z due to the evolving mass-metallicity relation: the red curve shows the luminosity of a galaxy at the metallicity threshold of 12+log[O/H]=8.94. The strong correlation between host luminosity and the degree of attenuation of the afterglow can also be seen: nearly all GRBs with dusty or “dark” afterglows are hosted within galaxies at the upper end of the mass distribution.  From \cite{Perley2016}.