  We compare pure luminosity evolution (PLE) models with recent data at low and
high redshift. These models assume that massive galaxies were assembled and
formed most of their stars at high redshift (z > 3) and have evolved without
merging or substantial dust obscuration since then. Our models span the full
range of plausible metallicities, initial mass functions (IMF's) and star
formation histories. We require them to reproduce the abundance of galaxies by
colour and luminosity in the Sloan Digital Sky Survey and we investigate
whether they can simultaneously fit (i) the observed galaxy counts as a
function of redshift in magnitude limited surveys with K < 20, and (ii) the
colour and M/L ratio evolution of red sequence galaxies in clusters. All models
that are consistent with (ii) predict galaxy counts at 1.5 < z < 3 which lie
above the observations. Models with an IMF slope similar to the Salpeter value
lie far above the data. We conclude that the majority of massive galaxies were
either assembled relatively late in this redshift interval or were
substantially obscured by dust at these redshifts.
