  Star formation history shows a gradual decline since the last 8-9 Gyr (z=1).
The bulk of present-day stellar mass and metal content was formed at redshifts
lower than 2-3, which is consistent with a hierarchical scenario of galaxy
formation. Observations of galaxy evolution during the last 2/3 of the Universe
age could be done in great details, and provide numerous insights on the origin
of the Hubble diagram. To some extent, the evolution and formation of
present-day elliptical and spiral galaxies could be related to the most rapidly
evolving galaxy populations at z ~ 1, namely the luminous IR galaxies and the
luminous compact galaxies.
