  The redshift distribution of near-IR selected galaxies is often used to
attempt to discriminate between the classical view of galaxy formation, in
which present-day luminous galaxies were assembled at early times and evolve
due to the passive aging of their stellar populations, and that of hierarchical
structure formation, in which galaxies were assembled more recently via the
merging of smaller objects. We carry out such a test here, by computing the
distribution of photometric redshifts of K_AB<22 galaxies in the Great
Observatories Origins Deep Field Survey GOODS Southern Field, and comparing the
results with predictions from a semi-analytic model based on hierarchical
structure formation, and a classical `passive evolution' model. We find that
the redshift distributions at z <~ 1.5 of both the hierarchical and passive
models are very similar to the observed one. At z>~1.5, the hierarchical model
shows a deficit of galaxies, while the passive model predicts an excess. We
investigate the nature of the observed galaxies in the redshift range where the
models diverge, and find that the majority have highly disturbed morphologies,
suggesting that they may be merger-induced starbursts. While the hierarchical
model used here does not produce these objects in great enough numbers, the
appearance of this population is clearly in better qualitative agreement with
the hierarchical picture than with the classical passive evolution scenario. We
conclude that the observations support the general framework of hierarchical
formation, but suggest the need for new or modified physics in the models.
