Life as a Quasi-Invariant: Functional Persistence Through Structural Turnover in Planetary Biospheres

This paper formalizes biospheric persistence as a quasi-invariant property at the level of planetary function. Distinguishing structural configuration S(t) from biospheric persistence capacity L(t), it demonstrates that large-scale perturbations typically induce structural turnover while maintaining continuity of life-supporting processes. The framework integrates feedback-mediated coupling, redundancy, metabolic flexibility, and threshold-driven reorganization to explain why biospheres persist through major transitions such as the Great Oxygenation Event and the Permian–Triassic extinction. The quasi-invariant formulation provides a minimal, non-teleological description of persistence in life-bearing systems, yields testable predictions regarding recovery dynamics and feedback intensification, and reframes astrobiological detection toward functional signatures rather than structural similarity.