  Assuming Active Galactic Nuclei are powered by accretion onto a massive black
holes we suggest that the growth of the central black hole due to the matter
accreted over the AGN lifetime causes an evolution of the luminosity and
spectrum. We show that the effective temperature of the UV continuum spectrum
is likely to be anti-correlated with the black-hole mass and with the
accretion-powered luminosity. We estimate the change in the equivalent width of
the emission lines due to the growth of the black hole and show that for
plausible evolutionary tracks and effective-temperature models the equivalent
width is anti-correlated with continuum luminosity thus implying an
evolutionary origin to the Baldwin effect.
