3. Natural Species Longevity and Lab-Achieved Longevity Are Mechanistically Distinct

Across species, longevity evolves by long-term co-optimization of maintenance (e.g., defenses, cancer control, immune function) under ecological constraints; within a species, interventions act on an already-optimized organismal design and therefore tend to expose tradeoffs (69). This distinction reconciles the broad conservation of some intervention responses with the fact that each species has private architectures and failure thresholds. A good illustration is temperature: within species, lower core temperature can slow reaction rates and extend lifespan, but across species, long-lived and/or high-temperature lineages have already compensated by strengthening antiaging defenses, so simple cross-species correlations can be misleading. This implies that cross-species analyses of aging mechanisms should treat lifespan and body temperature (and other ecological covariates) jointly, and that translating longevity interventions between and within species is not straightforward.