Encyclopedia of Gerontology and Population Aging

Living Edition
| Editors: Danan Gu, Matthew E. Dupre

Aging Definition

  • Giacinto LibertiniEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-69892-2_29-1



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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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.ASL NA2 Nord, Italian National Health ServiceFrattamaggioreItaly
  2. 2.Department of Translational Medical SciencesFederico II UniversityNaplesItaly

Section editors and affiliations

  • Giacinto Libertini
    • 1
  1. 1.ASL NA2 NordItalian National Health ServiceFrattamaggioreItaly