Geromedicine · Nov 5, 2026
Old worms, new tricks: Dynamical instability explains late-life rejuvenation in C. elegans
By Latumalea D, Molière A, Fedichev P et al.
How is it possible to double the lifespan of an organism already close to death? Many biological theories of aging fail to explain this phenomenon. At the Physics of Aging workshop, we used late-life lifespan extension in Caenorhabditis elegans to illustrate how a simple stochastic dynamical-systems model can naturally account for dramatic geriatric interventions. We build on a Langevin-type framework in which aging can occur in stable or unstable dynamical regimes, depending on whether slow, lifespan-determining modes are initially restoring or non-restoring. We argue that C. elegans operates in the unstable regime, a view supported independently by temporal scaling of survival curves, late-life mortality deceleration, and persistent lifespan effects following transient interventions. In the unstable regime, stochastic fluctuations are amplified over time until a failure threshold is reached as a first-passage event. The instability rate α sets the speed of this divergence, while the nonlinear feedback strength g, together with α, sets the failure boundary zmax = α/g. Auxin-induced degradation of DAF-2 in very old animals is interpreted as a late shift in dynamical parameters, and the model naturally accounts for the resulting lifespan extension without requiring reversal of accumulated structural damage. This reconciles persistent senescent pathologies with restored proteostasis and stress resilience, and suggests that altering regulatory instability, rather than reversing damage, can strongly reshape survival trajectories. More broadly, this work illustrates how low-dimensional, physics-inspired stochastic models can capture key features of aging and motivate new collaborations on late-life interventions.