SFL-LS-01: Theoretical Model for Human Lifespan Based on Average Functional Cycle of Representative Cells

This paper constructs the foundational quantitative lifespan model under the SFL unified framework, compatible with the cellular G₀ damage mechanism elaborated in the SFL-CELL serial. The core proposition states that individual theoretical lifespan is jointly determined by two fixed biological parameters: the average functional cycle duration of representative somatic cells (Tavg), and the species-specific total fixed cellular renewal quota (N). Cell functional cycle T refers to the intact survival period of a cell under undamaged G₀ architecture, not mitotic division cycle; persistent ΔGd damage shortens Tavg and accelerates the consumption of fixed renewal quota N. Core lifespan calculation formula L = Tavg × N Where L = estimated total human lifespan, Tavg = average functional cycle of representative cells, N = lifetime fixed cellular renewal cycles. To balance detection accessibility and systemic representativeness, skin cells, hematopoietic blood cells and optional vascular endothelial cells are selected as observational carriers. A standardized hypothetical numerical case verifies the calculation logic: when Tavg equals 8 years and N is fixed at 10, the predicted baseline healthy lifespan L reaches 80 years. This model differs from traditional telomere and oxidative stress aging theories by offering a concise quantifiable framework directly linked to cellular structural stability defined by G₀ and ΔGd. All shortened cycle phenomena traced in subsequent LS papers can be traced back to irreversible ΔGd(-) module collapse described in SFL-CELL, laying the quantitative foundation for analyzing premature aging, chronic disease consumption and anti-aging intervention effects.