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( Maximum lifespan)
Maximum life span is a measure of the maximum amount of time one or more members of a group has been observed to survive between birth and death. In animal studies, maximum life 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 former sense depends upon initial sample size.[1] The oldest recognized person on record is Jeanne Calment, a French woman who lived for 122 years. Prior to Calment, the undisputed record was just 114. Maximum recorded life span for humans has remained about 105-122 solar years throughout recorded history, despite steady improvements in life expectancy. Reduction of infant mortality has accounted for most of this increased average longevity, but since the 1960s mortality rates among those over 80 years have decreased by about 1.5% per year. "The progress being made in lengthening lifespans and postponing senescence is entirely due to medical and public-health efforts, rising standards of living, better education, healthier nutrition and more salubrious lifestyles."[3]. Animal studies suggest that further lengthening of human lifespan could be achieved through "calorie restriction mimetic" drugs or by directly reducing food consumption. Although calorie restriction has not been proven to extend the maximum human life span, as of 2006, results in ongoing primate studies are promising.[4] Small animals such as birds and squirrels rarely live to their maximum life span, usually dying of accidents, disease or predation. Grazing animals accumulate wear and tear to their teeth to the point where they can no longer eat, and they die of starvation.
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