title: Human models of aging and longevity.
abstract: BACKGROUND
  The aging phenotype in humans is very heterogeneous and can be described as a complex mosaic resulting from the interaction of a variety of environmental, stochastic and genetic-epigenetic variables. Therefore, each old person must be considered as a singleton, and consequently the definition of 'aging phenotype' is very difficult.
  
  
  OBJECTIVE
  We discuss the phenotype of centenarians, the best example of successful aging, as well as other models exploited to study human aging and longevity, such as families enriched in long-living subjects, twins and cohorts of unrelated subjects.
  
  
  METHODS
  A critical review of literature available until March 2008.
  
  
  CONCLUSIONS
  No single model can be considered the gold standard for the study of aging and longevity, instead the combination of results obtained from different models must be considered in order to better understand these complex phenomena. We propose that a systems biology concept such as that of 'bow-tie' architecture, useful for managing information flow, could help in this demanding task.
authors.affiliation: University of Bologna, Department of Experimental Pathology, Via S. Giacomo 12, 40126 Bologna, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Cevenini
authors.forename: L
authors.initials: L
authors.lastname: Invidia
authors.forename: F
authors.initials: F
authors.lastname: Lescai
authors.forename: S
authors.initials: S
authors.lastname: Salvioli
authors.forename: P
authors.initials: P
authors.lastname: Tieri
authors.forename: G
authors.initials: G
authors.lastname: Castellani
authors.forename: C
authors.initials: C
authors.lastname: Franceschi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D006801:Humans; D008136:Longevity; D008954:Models, Biological; D010641:Phenotype