"What the population tells us"

Simon Lilly, ETH Zurich

The large extragalactic surveys, exemplified by SDSS locally and
by the deep surveys such as COSMOS at high redshifts (in which the VLT
has played a major role) have opened up new avenues in the study of galaxy
evolution by enabling us to study the "population" as a whole.   I will discuss
a number of new insights that have come from taking this new approach.  These
are based on identifying a limited number of rather striking simplicities, or
symmetries, of the population and exploring analytically the implications of
these.  I will talk specifically about the formation of passive "quenched"
galaxies, the control of star-formation in the normal star-forming population,
the relative importance of "in situ'' star-formation and merging in building up
galaxies. I will end by showing that a high degree of convergence is emerging
between different phenomenological approaches to the evolution of galaxies.