While the human brain is considered a "masterpiece of creation," the minimum neural requirements for sustaining both life and autonomy remain poorly understood. This paper distinguishes the "minimum neural substrate" for biological survival (e.g., respiration and cardiac activity) from "functional survival," which requires the cognitive and emotional integrity necessary for autonomy. Analysis of the brain’s hierarchy reveals that while the brainstem and diencephalon ensures autonomic stability, higher-order systems like the limbic system and the cerebral cortex drives adaptive behavior. Clinical evidence from very early stroke rehabilitation (VER) suggests that recovery depends on a balance between adaptive reorganization and physiological tolerance. Additionally, traumatic brain injury (TBI) case studies demonstrate that consciousness can return via functional reintegration across surviving neural reservoirs, even following widespread disconnection. Radical examples, such as hydrocephalus and hemispherotomy, further illustrate that extensive anatomical loss can be compensated for by network flexibility and the sufficiency of unilateral circuits. Ultimately, functional recovery depends less on anatomical completeness than on the integrity of critical subcortical circuits and the brain's capacity for neuroplastic remodeling.