Color-redshift relations and several collective properties of galaxies (counts, redshift distributions, and the cosmic light) are assessed as tools for studying cosmology and the formation and evolution of galaxies. All of the calculated quantities and relations are found to be more sensitive to parameters of galaxy formation and evolution than to the cosmological model. Some fairly general conclusions are suggested, although details of the results are quite uncertain because of the unavoidably schematic nature of the models used to describe galactic evolution. Elliptical and S0 galaxies should appear significantly bluer at redshifts of at least 0.5 than they would without evolution and will appear very much bluer if seen while still actively forming stars. Evolution can produce very extended, and possibly not smooth, redshift distributions for galaxies selected by apparent magnitude. Magnitude-limited galaxy counts should show effects of evolution, amounting to factors of 3 or more at magnitudes of at least 20. If young galaxies are visible and identified in the counts, and if most galaxies are formed at redshifts not exceeding 6, the counts will show a pronounced excess in some magnitude interval brighter than 22 mag. The predicted intensity of the cosmic light is very sensitive to uncertainties in galactic evolution.
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B. M. Tinsley (1977) studied this question.