Aging is generally interpreted according to two opposing paradigms: 1) as a non-adaptive phenomenon, caused by the age-related failure of homeostatic mechanisms; 2) as a specific function, favored by natural selection, which determines the self-destruction of the organism, namely explaining aging as phenoptosis. This interpretation requires genetically determined and regulated age-specific mechanisms, now well documented by an impressive and growing scientific evidence. It follows that, in principle, aging is modifiable even up to the condition, already existing for many species, of "negligible senescence", alias unlimited longevity.