  We present a comprehensive study of 250,000 galaxies targeted by the Baryon
Oscillation Spectroscopic Survey (BOSS) up to z ~ 0.7 with the specific goal of
identifying and characterising a population of galaxies that has evolved
without significant merging. We compute a likelihood that each BOSS galaxy is a
progenitor of the Luminous Red Galaxies (LRGs) sample, targeted by SDSS-I/II up
z ~ 0.5, by using the fossil record of LRGs and their inferred star-formation
histories, metallicity histories and dust content. We determine merger rates,
luminosity growth rates and the evolution of the large-scale clustering between
the two surveys, and we investigate the effect of using different stellar
population synthesis models in our conclusions. We demonstrate that our sample
is slowly evolving (of the order of 2 +/- 1.5% per Gyr by merging). Our
conclusions refer to the bright and massive end of the galaxy population, with
Mi0.55 < -22, and M* > 1E11.2 Msolar, corresponding roughly to 95% and 40% of
the LRGs and BOSS galaxy populations, respectively. Our analysis further shows
that any possible excess of flux in BOSS galaxies, when compared to LRGs, from
potentially unresolved targets at z ~ 0.55 must be less than 1% in the
r0.55-band (approximately equivalent to the g-band in the rest-frame of
galaxies at z=0.55). When weighting the BOSS galaxies based on the predicted
properties of the LRGs, and restricting the analysis to the reddest BOSS
galaxies, we find an evolution of the large-scale clustering that is consistent
with dynamical passive evolution, assuming a standard cosmology. We conclude
that our likelihoods give a weighted sample that is as clean and as close to
passive evolution (in dynamical terms, i.e. no or negligible merging) as
possible, and that is optimal for cosmological studies.
