Biological perspectives on successful ageing

From a biological perspective, ageing is generally considered as a downhill phase of life, with a progressive decline in physiological functionality and an increase in the chances of chronic diseases and death. The onset of this phase of life does not start with birth because the early phase of life is a constructive phase of growth, development, maturation, and reproduction. Ageing sets in and happens progressively, exponentially, and intrinsically in the period of survival beyond the naturally evolved essential lifespan of a species. Ageing can be defined as a progressive shrinkage of the homeodynamic space having the fundamental characteristics of stress tolerance, damage control, and constant remodelling. Biologically successful ageing thus implies maintaining, recovering, or even enhancing those abilities that support survival and health in the framework of homeodynamic space.