(e, f) Survival of Drosophila during ageing without (control) and with supplementation of food at various concentrations of spermidine (as indicated). Autophagy-deficient flies (f) homozygous mutant for Atg7 (Δatg7) were compared with flies capable of autophagy (e) and heterozygous for Atg7 (control). For details of strains and additional wild-type controls, see Supplementary Information Methods and Fig. S6h, i. 