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The somatic mutation theory of ageing states that accumulation of mutations in somatic cells is the primary cause of aging. A comparison of somatic mutation rate across several mammal species found that the total number of accumulated mutations at the end of lifespan was roughly equal across a broad range of lifespans. [ 16 ]
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
According to this theory, life span development has multiple trajectories (positive, negative, stable) and causes (biological, psychological, social, and cultural). Individual variation is a hallmark of this theory – not all individuals develop and age at the same rate and in the same manner. [15] Bronfenbrenner's ecological theory
The other two psychosocial theories are the disengagement theory, with which the activity comes to odds, and the continuity theory which modifies and elaborates upon the activity theory. [5] Though in recent years the acceptance activity theory has diminished, it is still used as a standard to compare observed activity and life satisfaction ...
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 .
Senescence (/ s ɪ ˈ n ɛ s ə n s /) or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle.
The mitochondrial theory of ageing has two varieties: free radical and non-free radical. The first is one of the variants of the free radical theory of ageing. It was formulated by J. Miquel and colleagues in 1980 [1] and was developed in the works of Linnane and coworkers (1989). [2] The second was proposed by A. N. Lobachev in 1978. [3]
The physiological importance for cell senescence has been attributed to prevention of carcinogenesis, and more recently, aging, development, and tissue repair. [9] Senescent cells contribute to the aging phenotype , including frailty syndrome , sarcopenia , and aging-associated diseases . [ 10 ]