Studies of the far-infrared extragalactic background (FIRE) provide information on the star formation history of the Universe which is complementary to that given by optical observations, The upper limits on the FIRE intensity resulting from recent analyses of COBE/FIRAS data entail interesting constraints on the possibility that most of the star formation activity occurring during early phases of galaxy evolution takes place within dusty gas clouds, The tentative detection of the FIRE reported by Puget et al. suggests that the star formation and metal production histories might have been substantially different, at high redshifts, from those inferred from optical data.
