From the moment of birth, every human cell begins accumulating silent errors — somatic mutations that no supplement can prevent and no biohack can undo. A new mathematical model published in NPJ Aging places the absolute ceiling of human life at approximately 190 years, grounded not in pessimism but in the quiet logic of cellular biology. The finding arrives as a corrective to an era of longevity optimism, reminding us that the body is not a problem to be solved but a system with its own deep grammar — one written, in part, in the neurons that live as long as we do.