Abstract
Quasars are now observed to redshifts beyond 4, offering one of the few direct probes of conditions in the centers of galaxies early in their evolution. Analysis of the broad emission lines suggests that the emitting gas often has a metallicity well above solar, and that metal abundances increase with redshift and luminosity. These abundances are similar to those inferred to have existed in the cores of massive galaxies early in their evolution, suggesting that observable quasars occur near the end of the epoch when rapid star formation dominated by massive stars has created an enriched interstellar medium.
