Average Ca II index evolution of 0.8–1.0 M_⊙ stars with near-solar metallicity derived from their rotation period evolution compared with previous studies. These include (i) the relationship of Lorenzo-Oliveira et al. (2018) for 0.8 and 1.0 M_⊙ stars with solar metallicity, (ii) the age-activity relationships of Mamajek & Hillenbrand (2008) for F7-K2 dwarfs (0.5 < B−V < 0.9), and (iii) the age-activity relationship of Zhang et al. (2019) for stars with 4000 K < T_eff < 5500 K.