The impact of

We complement our study of $\alpha/{\rm Fe}$ enhanced stellar population models of Lick absorption indices (Thomas et al. [CITE]) by comparing two sets of $\alpha/{\rm Fe}$ enhanced models. In both models the impact on Lick indices due to $\alpha/{\rm Fe}$ enhancement is accounted for through a modification of the stellar absorption line-strengths using the response functions of Tripicco & Bell ([CITE]). One set of models, however, uses solar-scaled, the other $\alpha/{\rm Fe}$ enhanced stellar evolutionary tracks. Since the $\alpha/{\rm Fe}$ enhanced tracks are hotter than the solar-scaled ones (Salasnich et al. [CITE]), the correspondent stellar population models have slightly weaker metallic indices (i.e. ${\rm Mg}\, b$, $\langle {\rm Fe}\rangle$ etc.) and stronger Balmer line indices (${\rm H}\beta$) (Maraston et al. [CITE]). Here we explore quantitatively the impact of this effect on the $\alpha/{\rm Fe}$ ratios, metallicities and ages that are derived for elliptical galaxies. We find that the modest decrease of the metallic indices ${\rm Mg}\, b$ and $\langle {\rm Fe}\rangle$ balance each other, such that fully consistent $\alpha/{\rm Fe}$ ratios are derived for stellar systems using $\alpha/{\rm Fe}$ enhanced models with either solar-scaled or $\alpha/{\rm Fe}$ enhanced stellar tracks. The decrease of the metallic indices and the increase of ${\rm H}\beta$ conspire in a way that also consistent metallicities are obtained. The derived ages, instead, are significantly different. The inclusion of $\alpha/{\rm Fe}$ enhanced stellar tracks leads to the derivation of ages as high as ~30 Gyr for elliptical galaxies. For the same objects, ages not older than 15 Gyr are obtained, if $\alpha/{\rm Fe}$ enhanced models using solar-scaled tracks are adopted. This may indicate that current stellar evolutionary models overestimate the bluing of stellar evolutionary tracks due to $\alpha/{\rm Fe}$ enhanced chemical mixtures at super-solar metallicities