We explore possible correlations between the light profile shapes of early-type galaxies, as parameterized by the Sérsic index n, and relevant stellar population parameters, which were obtained from spectra of extremely high signal-to-noise and stellar population models that provide an age indicator that is virtually free of the effects of metallicity. We do not find any robust correlation between n and mean age or metallicity. However, we find evidence for a strong positive correlation between n and [Mg/Fe] abundance ratio. We speculate that early-type galaxies settle up their structure on short time-scales in agreement with those imposed by their [Mg/Fe] ratios, suggesting that the global structure was already at place at high z.