We investigate the evolution of mass-selected early-type field galaxies using a sample of 28 gravitational lenses spanning the redshift range 0 \lesssim z \lesssim 1 .
Based on the redshift-dependent intercept of the fundamental plane in the rest frame B band , we measure an evolution rate of d \log ( M / L ) _ { B } / dz = -0.56 \pm 0.04 ( all errors are 1 \sigma unless noted ) if we directly compare to the local intercept measured from the Coma cluster .
Re-fitting the local intercept helps minimize potential systematic errors , and yields an evolution rate of d \log ( M / L ) _ { B } / dz = -0.54 \pm 0.09 .
An evolution analysis of properly-corrected aperture mass-to-light ratios ( defined by the lensed image separations ) is closely related to the Faber-Jackson relation .
In rest frame B band we find an evolution rate of d \log ( M / L ) _ { B } / dz = -0.41 \pm 0.21 , a present-day characteristic magnitude of M _ { * 0 } = -19.70 + 5 \log h \pm 0.29 ( assuming a characteristic velocity dispersion of \sigma _ { DM* } = 225 { km s ^ { -1 } } ) , and a Faber-Jackson slope of \gamma _ { FJ } = 3.29 \pm 0.58 .
The measured evolution rates favor old stellar populations ( mean formation redshift \langle z _ { f } \rangle > 1.8 at 2 \sigma confidence for a Salpeter initial mass function and a flat \Omega _ { m } = 0.3 cosmology ) among early-type field galaxies , and argue against significant episodes of star formation at z < 1 .