Physical Life of a Prebiotic Vesicle: Osmotic Breathing

We propose a minimal physical model of a prebiotic vesicle driven by environmental wet–dry cycles. Periodic changes in external osmolarity generate an osmotic engine that induces repeated shrinking and swelling of the vesicle. If at least one class of slowly permeable osmolytes is present inside, a physical memory of composition emerges, membrane tension increases, and threshold phenomena such as transient pores, shape instabilities, and division occur. We show that growth, cyclic stability, and primitive reproduction can arise purely from non‑equilibrium physical processes, without genetic code or enzymes.