Maximum Lifespan

Maximum life span is a measure of the maximum number of years a member of a group has been observed to survive. Maximum life span literally corresponds to the age at which the oldest known member of a Species or experimental group has died. Maximum life span is contrasted to Mean Life Span ( Average Lifespan or Life Expectancy ). Mean Life Span varies with susceptibility to disease, Accident , Suicide and Homicide , whereas maximum life span is determined by "rate of aging". Epistemologically maximum life span also depends upon initial sample size. In animal studies, maximum life span is typically taken to be the Mean Life Span of the most long-lived 10% of a given Cohort . This may be taken to be "definition 2" of 'maximum life span.'

OVERVIEW

In Ancient Rome Average Life Span was 22 years, but by the mid−1800s the typical North American lived to be 40. Today, people in the most developed countries have an Average Life Span of about 80. Reduction of infant mortality has accounted for most of the increased Longevity , but since the 1960s Mortality Rate s among those over 80 years has been decreasing by about 1.5% per year. Maximum life span for humans, however, has remained about 115−120 all through known history. The oldest-ever person was Jeanne Calment , a French woman who lived for 122 years and 164 days.

Advances in medicine, Calorie Restriction with adequate nutrition, or other interventions are said to have slowed the Aging Process .

The maximum life span of each species is different. These differences demonstrate the role of s and Squirrel s rarely live to their maximum life span, usually dying of Accident s and Disease . Grazing animals show wear-and-tear to their teeth to the point where they can no longer eat, and they die of Starvation .

The maximum life span of most species has not been accurately determined because the data collection has been minimal and the number of species studied in captivity (or by monitoring in the wild) has been small. Maximum life span is usually longer for species that are larger, can fly and have larger brains. Of the approximately 30,000 genes in the human Genome , it is estimated that only 2% of these are different from those of a chimpanzee, which has half the estimated maximum life span of a human. The difference in Longevity could be due to as few as a hundred Gene s or less, however there may be other factors which influence the life span of chimpanzees.

Identical Twin s tend to die within 3 years of each other, whereas fraternal twins tend to die within 6 years. Aging Theories associated with DNA include programmed aging (or programmed aging-resistance) and theories that link aging with DNA damage/mutation or DNA Repair capability.

Plant s tend to come in Annual s, Biennial s, and Perennial s. The longer-lived perennials, woody-stemmed plants such as trees and bushes, often live for hundreds and even thousands of years. The oldest-known tree is the Bristlecone Pine , at 4700 years; it has been claimed that Creosote Bush es live for 11,000 years, but claims of this nature are based on estimates, rather than actual Ring Count s.

INCREASING MAXIMUM LIFE SPAN

Currently, the only (non- the life extending benefits of calorie restriction are gained immediately at any age upon beginning calorie restriction and ended immediately at any age upon resuming full feeding [ SCIENCE ; Mair,W; 301:1731-1733 (2003) ].

Mammals fed Anti-oxidant s show up to a 30% increase in Mean Life Span , but no increase in maximum life span. Antioxidants are most valuable for animals that are cancer-prone, or subjected to Radiation or Chemical toxins. There are evidently homeostatic mechanisms in cells that govern the amount of allowable antioxidant activity. Many Life-extensionists have dismissed the value of antioxidants simply because they have not been shown to increase maximum life span -- as if extending Mean Life Span was not important.

Many Transgenic species of mice have been created which have maximum life span greater than that of wild-type or laboratory mice, including Ames dwarf mice, Snell dwarf mice, mice with increased Mitochondria l Catalase , etc.

Some biomedical Gerontologists (the kind of gerontologists who search for ways to extend maximum life span) believe that Biomedical Molecular Engineering can someday extend maximum lifespan and even bring about Rejuvenation .

One such researcher is Aubrey De Grey , who calls his project to reverse the damage we call ''aging'' ''' SENS ''' (''' Strategies For Engineered Negligible Senescence '''). Dr. de Grey has established the The Methuselah Mouse Prize to award money to researchers who can extend the maximum life span of mice.

RESEARCH DATA CONCERNING MAXIMUM LIFE SPAN

A comparison of the Heart Mitochondria in rats (4-year maximum life span) and Pigeon s (35-year maximum life span) showed that pigeon Mitochondria leak fewer Free-radicals than rat mitochondria, despite the fact that both animals have similar Metabolic Rate and Cardiac output

OF AGING AND DEVELOPMENT 98:95-111 (1997)

For Mammal s there is a direct relationship between Mitochondria l Membrane saturation and maximum life span

OF LIPID RESEARCH 39:1989-1994 (1998)

Studies of the Liver Lipid s of Mammal s and a Bird ( Pigeon ) show an inverse relationship between maximum life span and number of Double Bond s

OF GERONTOLOGY 55A(6):B286-B291 (2000)

Maximum life span correlates negatively with Antioxidant Enzyme levels and correlates positively with lower rate of Free-radicals production and higher rate of DNA Repair

OF COMPARATIVE PHYSIOLOGY B 168:149-158 (1998)

Females express both more Mn−SOD and more glutathione peroxidase antioxidant Enzyme s than males, and this has been suggested to be the reason females live longer than males in Mammal ian species

LETTERS; Vina,J; 579(12):2541-2545 (2005)

The maximum life span of transgenic mice has been extended about 20% by overexpression of human Catalase targeted to Mitochondria

SCIENCE

A comparison of 7 non- Primate Mammal s (mouse, hamster, rat, guinea-pig, rabbit, pig and cow) showed that the rate of Mitochondrial superoxide and hydrogen peroxide production in Heart and Kidney were inversely correlated with maximum life span

RADICAL BIOLOGY & MEDICINE 15:621-627 (1993)

A study of 8 non- Primate Mammals showed a direct correlation between maximum life span and oxidative damage to mtDNA ( Mitochondrial DNA ) in heart & brain

FASEB JOURNAL; Barja,G; 14(2):312-318 (2000)

A study of several species of mammals and a bird (pigeon) indicated a linear relationship between oxidative damage to protein and maximum life span

GERONTOLOGY 31(3):387-392 (1996)

There is a direct correlation between DNA Repair and maximum life span for Mammal ian species

OF AGING AND DEVELOPMENT; Cortopassi, GA; 91:211-218 (1996)

Drosophila (fruit-flies) bred for 15 generations by only using eggs that were laid toward the end of reproductive life achieved maximum life spans 30% greater than that of controls

OF GERONTOLOGY 55A(11):B552-B559 (2000)

A mutation in the age−1 gene of the Nematode Worm Caenorhabditis Elegans inceased Mean Life Span 65% and maximum life span 110%

118:75-86 (1988)

Fat -specific Insulin Receptor KnockOut (FIRKO) mice have reduced fat mass, normal calorie intake and an increased maximum life span of 18%

SCIENCE

The capacity of mammalian species to detoxify the Carcinogenic chemical benzo(a)pyrene to a water-soluble form also correlates well with maximum life span

CELL RESEARCH 116:359-364 (1978)

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Maximum Lifespan