In animal studies, maximum span is often taken to be the mean life span of the most long-lived 10% of a given cohort. By another definition, however, maximum life span corresponds to the age at which the oldest known member of a species or experimental group has died. Calculation of the maximum life span in the latter sense depends upon initial sample size.
Maximum life span contrasts with mean life span (average life span, life expectancy), and longevity. Mean life span varies with susceptibility to disease, accident, suicide and homicide, whereas maximum life span is determined by the rate of aging. Longevity refers only to the characteristics of the especially long lived members of a population, such as infirmities as they age or compression of morbidity, and not the specific life span of an individual.
The longest living person whose dates of birth and death were verified according to the modern norms of Guinness World Records and the Gerontology Research Group was Jeanne Calment (1875–1997), a French woman who reportedly lived to 122.