The dramatic decline in human lifespan described in the biblical genealogies of Genesis 5 and 11 presents a unique intersection of theological narrative and biological inquiry. This paper proposes a multidisciplinary theory to explain this phenomenon, integrating textual analysis with principles from biogerontology and population genetics. We argue that the Genesis Flood narrative represents a catastrophic event that triggered a fundamental shift in human life-history strategy. Statistical analysis of the biblical data reveals a synchronized decline in total lifespan, age at sexual maturity, and reproductive window—a triad consistent with an adaptive transition from a slow to a fast life-history strategy in response to postdiluvian environmental harshness and a genetic bottleneck. This model explains the decline as a trade-off favoring rapid reproduction over somatic maintenance. The case of Job’s divinely granted 140 years is analyzed not as a reversion to antediluvian norms, but as a supernatural blessing within the new biological paradigm, affirming divine sovereignty over natural law. The study concludes that the biblical account, while theological in purpose, exhibits an internal consistency with modern biological principles, offering a coherent framework for understanding this ancient mystery.