Stellar ages estimated with CIGALE. Upper panel: ages of the (oldest) stellar population for free-age models as a function of redshift. Black triangles: two-populations model, green circles: decl.-τ model, magenta crosses: rising-τ model. The red steps correspond to the age adopted for the models with fixed ages. Lower panel: mass weighted ages for all the models: same symbols as in the upper panel are used for the free-age models, blue squares and red diamonds are added for the fixed-age rising-τ model and two-populations models, respectively. The curves correspond to the age at redshift z for a redshift formation z_f = 8 (thick line), z_f = 5 (thin line), and z_f = 2.5 (dotted line).