Relation between the central stellar mass surface density of our disc galaxies (measured by the mean surface mass density within 1 kpc) and the stellar mass. The red dashed line corresponds to the fit to the data points in the highest redshift bin (0.9 < z < 1.1). The green lines at each redshift bin are the fits to the data points using a fixed slope equal to that measured at the highest redshift bin. The lower right panel shows the evolution with redshift of the central surface mass density of galaxies of similar mass to the Milky Way (i.e. M_stellar = 5×10¹⁰ M_⊙). Errors come from bootstrapping 10⁴ times our measurements. In contrast to the evolution of the stellar surface mass density at the edge of the galaxy, the central density remains relatively unchanged over the last 8 Gyr.