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Aging Definition

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Encyclopedia of Gerontology and Population Aging

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Senescence

Definition

Aging may be defined in two ways that could be considered equivalent. The first describes the phenomenon as an age-related decline of biological functions, e.g., “progressive loss of function accompanied by decreasing fertility and increasing mortality with advancing age” (Kirkwood and Austad 2000, p. 233); “a persistent decline in the age-specific fitness components of an organism due to internal physiological deterioration” (Rose 1991, p. 38); and “any time-dependent change which occurs after maturity of size, form, function is reached and which is distinct from daily, seasonal and other biological rhythms” (Rockstein et al. 1977, p. 4). The second way describes the phenomenon as an age-related increase in mortality, i.e., “increasing mortality with increasing chronological age in populations in the wild” (Libertini 1988, p. 145) or “actuarial senescence” (Holmes and Austad 1995, p. B61), or “age-dependent increase in the risk of death” (Lenart et al. 2018...

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Correspondence to Giacinto Libertini .

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Libertini, G. (2019). Aging Definition. In: Gu, D., Dupre, M. (eds) Encyclopedia of Gerontology and Population Aging. Springer, Cham. https://doi.org/10.1007/978-3-319-69892-2_29-1

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  • DOI: https://doi.org/10.1007/978-3-319-69892-2_29-1

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  • Print ISBN: 978-3-319-69892-2

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