Specific SFR (sSFR) as a function of cosmic time (lower x-axis) and redshift (upper x-axis) for our SMGs and the flux-limited sample of ALESS SMGs. The plotted data points represent the mean values of our data and the ALESS SMG data binned in redshift and sSFR (each of our bin contains four sources, while the ALESS data have five values in each bin). The error bars represent the standard error of the mean. The horizontal dashed lines indicate the full sample median sSFRs of Gyr^-1 and Gyr^-1, respectively. The blue dash-dotted line corresponds to the relationship log (sSFR/ Gyr^-1) = −0.12 × (τ_univ/ Gyr) + 0.71 derived by Koprowski et al. (2016).