16. Species Longevity Is Set by Evolved Systems-Level Maintenance

Species longevity is an evolved systems-level property: a coadapted set of fidelity and maintenance processes (repair, turnover, buffering, stem cell function, tissue architecture, etc.) scaled by natural selection to the rate of damage production, ecological niche, extrinsic mortality, body temperature, body size, and life history. Intrinsic human lifespan is up to half heritable (30, 31). Long-lived, high-temperature species have more robust fidelity and maintenance, which is one reason why dramatic lifespan extension in experimental settings is easier to achieve in short-lived species. In long-lived species, selection has already favored longevity-associated mechanisms, leaving fewer accessible targets for intervention. Therefore, extending human lifespan will likely require different leverage points (e.g., combinations of interventions, replacement/regeneration, deeper reset strategies), because humans already sit closer to robust maintenance regimes. At the same time, some interventions work across species because they target public, conserved mechanisms of nutrient sensing, stress response, or maintenance (32).