The aging process in most organisms is enormously complex, involving a multitude of integrated molecular pathways that define and modulate the gradual cellular, tissue and system-level changes that evoke the aging phenotype. Despite this sophistication, the root causes underlying the susceptibility of an organism to aging may be comparatively straightforward. Here, I posit that biological aging can be explained using established principles from physics (nonequilibrium thermodynamics and Newtonian), evolutionary theory, and information theory. A logical conclusion of the theory presented here is that aging is inevitable in all individual organisms given sufficient time. It is also argued here how stipulations derived from the second law of thermodynamics and Newtonian physics may be critical in defining evolutionary fitness landscapes that vary according to the ability of an organism to resist the loss of data in information-encoding biomolecules (DNA), and possibly other biocomponents subject to irreversible fidelity loss in some organisms, and that this may largely explain the differences in longevity amongst many organisms.