  Our view of galaxy evolution has been dramatically enhanced by the recent
deep field submm surveys carried out with the SCUBA camera on the JCMT. SCUBA
has discovered a population of luminous infrared galaxies at redshifts ~1-4
that emit most of their energy at far-IR/submm wavelengths. The cumulative
surface density of submm sources (~10,000 per sq.deg with S_850 > 1 mJy)
appears to be sufficient to account for nearly all of the 850 micron
extragalactic background. The SCUBA sources are plausibly the high-redshift
counterparts of more local (z < 1) luminous infrared galaxies that have been
identified in IRAS and ISO deep field surveys, the majority of which appear to
be major mergers of gas-rich disks accompanied by dust-enshrouded nuclear
starbursts and powerful AGN. The SCUBA sources are plausibly the progenitors of
the present-day spheroidal population. This major event in galaxy evolution,
equal in bolometric luminosity to that observed at optical wavelengths, is
largely missed by current UV/optical surveys.
