  The high redshifts of the most distant known quasars, and the best estimates
of their black hole masses, require that supermassive black holes (SMBHs) must
have formed very early in history. Several mechanisms for creating and growing
these holes have been proposed. Here we present an evaluation of the timescales
needed for various critical processes in order to discriminate between the
proposed scenarios. We find in particular that mergers alone are not able to
grow the black holes at a sufficient rate. Accretion models offer a solution
and we use accretion timescales to constrain the manner in which the black hole
was first formed. This analysis implies, but does not require, the action of
some unconventional process.
