Schematic representation of possible effects of different factors on systemic resilience. Schematic representation of possible effects of different factors on systemic resilience. While effects of some factors are only detrimental (A) or positive (C), the effect of other factors on resilience peaks at intermediate levels (B). Effects of aging on resilience (D) are moderated by the mechanisms summarized in Fig. 1. Marten Scheffer et al. PNAS 2018;115:47:11883-11890 ©2018 by National Academy of Sciences