Aging and aging theories

Several theories have sought to explain aging, here precisely defined as “increasing mortality with increasingchronological age in populations in the wild”. They all fall within one of two opposite and incompatible paradigms.For the first (“old paradigm”), aging is the result of degenerative phenomena that natural selectioncannot counteract completely, due to insufficient strength or opposing selective pressures. For the second(“new paradigm”), aging is favoured by natural selection in terms of supra-individual selection: it belongs to abroader category of phenomena, on the whole defined as “phenoptosis”, which are explicable only in terms ofsupra-individual selection. For the new paradigm, aging is a specific function that is genetically determined andregulated, with its own physiology, pathology and phylogeny. This paper describes the theoretical argumentsand the empirical evidence that support or are in contrast with each of the two paradigms. Subsequently, onthe basis of an imposing and authoritative amount of research, aging mechanisms at the cellular and organismallevels are described. The clear existence of such mechanisms is indispensable proof to support the newparadigm and is in complete and unsolvable contrast with the old paradigm.