Star formation history corresponding to LRG spectral template of Fig. 1. Top: Number of stars formed per logarithmic time interval (t expressed in years, curve normalized for a 10¹² M_⊙ galaxy). Almost all of the stars are formed in the first couple of billion years; note that the recent "spike" represents a tiny fraction (~10⁻⁸) of the total number of stars. Bottom: Mean metallicity of the population as a function of time. Note that the details of these functions are rather poorly constrained.