  We present a characterization of the local luminosity-color, bi-variate
distribution of IRAS galaxies from the 1.2Jy sample, selected at 60 micron. The
S60/S100 infrared color is used as the best single parameter description of the
IR spectral energy distribution of galaxies. We derive an analytical form of
the distribution and use it to constrain the effect of the IR color
distribution on evolution models for high redshift, farIR luminous galaxies.
Our adopted evolution retains the locally observed correlation between
luminosity and color, such that the larger characteristic luminosities at
higher redshift have a warmer characteristic color. The width of the color
distribution at a given luminosity remains constant for all redshifts. We
demonstrate that there is the potential for both hotter and colder sources to
be missed in cosmological surveys. An evolving bi-variate luminosity function
coupled with the cold source bias of sub-mm selected surveys suggests the
existence of a large population of cold sources appearing in such surveys.
Likewise, a hot source bias for most SIRTF wavebands together with a bi-variate
model suggests an excess of hot sources being selected. We test the
evolutionary form against available data for higher redshift, farIR galaxies.
The data do not reveal evidence for any strong evolution in the characteristic
luminosity-color distribution as a function of redshift over 0<z<1. However,
there is marginal evidence for a broadening of the color distribution at higher
redshifts, consistent with our locally characterized trend of a broadening in
the IR color distribution at the highest luminosities.
