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The two theories; non-adaptive, and adaptive, are used to explain the evolution of senescence, which is the decline in reproduction with age. [8] The non-adaptive theory assumes that the evolutionary deterioration of human age occurs as a result of accumulation of deleterious mutations in the germline. [8]
Selectivity theory (aging) Socioemotional selectivity theory; Stage-crisis view; Stem cell theory of aging; Stereotype embodiment theory; T. Telomere theory of aging; V.
Aging theories based on group selection; Antagonistic pleiotropy hypothesis; C. Cross-linking theory of aging; D. Disposable Soma Theory; DNA damage theory of aging; E.
Ageing (or aging in American English) is the process of becoming older. The term refers mainly to humans , many other animals , and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal . [ 1 ]
Biogerontology should not be confused with geriatrics, which is a field of medicine that studies the treatment of existing disease in aging people, rather than the treatment of aging itself. There are numerous theories of aging, and no one theory has been entirely accepted.
All evolutionary theories of aging rest on the basic mechanisms that the force of natural selection declines with age. [19] [20] Mechanistic theories of aging can be divided into theories that propose aging is programmed, and damage accumulation theories, i.e. those that propose aging to be caused by specific molecular changes occurring over time.
[6] Biomedical theories hold that one can age successfully by caring for physical health and minimizing loss in function, whereas psychosocial theories posit that capitalizing upon social and cognitive resources, such as a positive attitude or social support from neighbors, family, and friends, is key to aging successfully. [7]
The metabolic stability theory of aging suggests it is the cells ability to maintain stable concentration of ROS which is the primary determinant of lifespan. [37] This theory criticizes the free radical theory because it ignores that ROS are specific signalling molecules which are necessary for maintaining normal cell functions. [37]