  Supernova (SN) cosmology is based on the assumption that the corrected
luminosity of SN Ia would not evolve with redshift. Recently, our age dating of
stellar populations in early-type host galaxies (ETGs) from high-quality
spectra has shown that this key assumption is most likely in error. It has been
argued though that the age-Hubble residual (HR) correlation from ETGs is not
confirmed from two independent age datasets measured from multi-band optical
photometry of host galaxies of all morphological types. Here we show, however,
that one of them is based on highly uncertain and inappropriate
luminosity-weighted ages derived, in many cases, under serious template
mismatch. The other dataset employs more reliable mass-weighted ages, but the
statistical analysis involved is affected by regression dilution bias, severely
underestimating both the slope and significance of the age-HR correlation.
Remarkably, when we apply regression analysis with a standard posterior
sampling method to this dataset comprising a large sample ($N=102$) of host
galaxies, very significant ($> 99.99 \%$) correlation is obtained between the
global population age and HR with the slope ($-0.047 \pm 0.011$~mag/Gyr) highly
consistent with our previous spectroscopic result from ETGs. For the local age
of the environment around the site of SN, a similarly significant ($> 99.96
\%$) correlation is obtained with a steeper slope ($-0.057 \pm 0.016$ mag/Gyr).
Therefore, the SN luminosity evolution is strongly supported by the age dating
based on multi-band optical photometry and can be a serious systematic bias in
SN cosmology.
