Maximum life span (or, for humans, maximum reported age at death) is a measure of the maximum amount of time one or more members of a population have been observed to survive between birth and death. The term can also denote an estimate of the maximum amount of time that a member of a given species could survive between birth and death, provided circumstances that are optimal to that member's

longevity The word " longevity" is sometimes used as a synonym for "life expectancy" in demography. However, the term ''longevity'' is sometimes meant to refer only to especially long-lived members of a population, whereas ''life expectancy'' is always d ...

. Most living species have an upper limit on the number of times

somatic Somatic may refer to: * Somatic (biology), referring to the cells of the body in contrast to the germ line cells ** Somatic cell, a non-gametic cell in a multicellular organism * Somatic nervous system, the portion of the vertebrate nervous sys ...

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

not expressing telomerase can divide. This is called the Hayflick limit, although this number of cell divisions does not strictly control lifespan.

Definition

In animal studies, maximum span is often taken to be the

mean life span Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...

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 the initial sample size. ''Maximum life span'' contrasts with ''

( average life span'', '' life expectancy)'', and ''

''. Mean life span varies with susceptibility to disease, accident,

suicide Suicide is the act of intentionally causing one's own death. Mental disorders (including depression, bipolar disorder, schizophrenia, personality disorders, anxiety disorders), physical disorders (such as chronic fatigue syndrome), and s ...

and

homicide Homicide occurs when a person kills another person. A homicide requires only a volitional act or omission that causes the death of another, and thus a homicide may result from accidental, reckless, or negligent acts even if there is no inten ...

, whereas maximum life span is determined by "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 The compression of morbidity in public health is a hypothesis put forth by James Fries, professor of medicine at Stanford University School of Medicine. The hypothesis was supported by a 1998 study of 1700 University of Pennsylvania alumni over a pe ...

'', and not the specific life span of an individual.

In humans

Demographic evidence

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 French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

woman who is verified to have lived to 122. Reduction of infant mortality has accounted for most of the increased average life span

, 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 Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...

is entirely due to medical and public-health efforts, rising standards of living, better education, healthier nutrition and more salubrious lifestyles." Animal studies suggest that further lengthening of median human lifespan as well as maximum 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 , results in ongoing primate studies have demonstrated that the assumptions derived from rodents are valid in primates. It has been proposed that no fixed theoretical limit to human longevity is apparent today. Studies in the biodemography of human longevity indicate a ''late-life mortality deceleration law'': that death rates level off at advanced ages to a late-life mortality plateau. That is, there is no fixed upper limit to human longevity, or fixed maximal human lifespan. This law was first quantified in 1939, when researchers found that the one-year probability of death at advanced age asymptotically approaches a limit of 44% for women and 54% for men. However, this evidence depends on the existence of a late-life plateaus and deceleration that can be explained, in humans and other species, by the existence of very rare errors. Age-coding error rates below 1 in 10,000 are sufficient to make artificial late-life plateaus, and errors below 1 in 100,000 can generate late-life mortality deceleration. These error rates cannot be ruled out by examining documents (the standard) because of successful pension fraud, identity theft, forgeries and errors that leave no documentary evidence. This capacity for errors to explain late-life plateaus solves the "fundamental question in aging research is whether humans and other species possess an immutable life-span limit" and suggests that a limit to human life span exists. A theoretical study suggested the maximum human lifespan to be around 125 years using a modified

stretched exponential function The stretched exponential function f_\beta (t) = e^ is obtained by inserting a fractional power law into the exponential function. In most applications, it is meaningful only for arguments between 0 and +∞. With , the usual exponential functio ...

for human survival curves. In another study, researchers claimed that there exists a maximum lifespan for humans, and that the human maximal lifespan has been declining since the 1990s. A theoretical study also suggested that the maximum human life expectancy at birth is limited by the human life characteristic value δ, which is around 104 years. The United Nations has undertaken an importan
Bayesian sensitivity analysis of global population burden based on life expectancy projection at birth in future decades
The 2017 95% prediction interval of 2090 average life expectancy rises as high as +6 (106, in Century Representation Form) by 2090, with dramatic, ongoing, layered consequences on world population and demography should that happen. The prediction interval is extremely wide, and the United Nations cannot be certain. Organizations like the Methuselah Foundation are working toward an end to senescence and practically unlimited human lifespan. If successful, the demographic implications for human population will be greater in effective multiplier terms than any experienced in the last five centuries if maximum lifespan or the birthrate remain unlimited by law. Modern Malthusian predictions of overpopulation based on increased longevity have been criticized on the same basis as general population alarmism (see Malthusianism).

Non-demographic evidence

Evidence for maximum lifespan is also provided by the dynamics of physiological indices with age. For example, scientists have observed that a person's VO₂max value (a measure of the volume of oxygen flow to the cardiac muscle) decreases as a function of age. Therefore, the maximum lifespan of a person could be determined by calculating when the person's VO₂max value drops below the basal metabolic rate necessary to sustain life, which is approximately 3 ml per kg per minute. On the basis of this hypothesis, athletes with a VO₂max value between 50 and 60 at age 20 would be expected "to live for 100 to 125 years, provided they maintained their physical activity so that their rate of decline in VO₂max remained constant". Longitudinal variations of physiological indices, as diverse as complete blood counts (CBC) or physical activity records collected by wearable devices, along individual aging trajectories revealed a linear increase of the organism state fluctuations range with age. The broadening could be explained by a progressive loss of physiological resilience measured by the inverse auto-correlation times of the organism state fluctuations. Extrapolation of this data suggested that organism state recovery time and variance could simultaneously diverge at a critical point of 120 – 150 years of age corresponding to a complete loss of resilience and hence should be incompatible with survival. The criticality resulting in the end of life is an intrinsic biological property of an organism that is independent of stress factors and signifies a fundamental or absolute limit of human lifespan. The evidence of the divergence of the organism state fluctuations and hence the loss of resilience at a limiting age of approximately 130 years can also be found in the age-dependent variation of the DNA-methylation profiles obtained from human blood samples. Age dynamics of the body mass

In animals

Small animals such as birds and

squirrel Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

s rarely live to their maximum life span, usually dying of accidents, disease or predation. The maximum life span of most species is documented in the AnAge repository (The Animal Ageing and Longevity Database). Maximum life span is usually longer for species that are larger or have effective defenses against predation, such as bird flight, chemical defenses or living in social groups. The differences in life span between species demonstrate the role of genetics in determining maximum life span ("rate of aging"). The records (in years) are these: *for common house mouse, 4 * for Brown rat, 3.8 *for dogs, 29 (See List of oldest dogs) *for

cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

s, 38 (See List of oldest cats) * for common cranes, 43 *for

polar bear The polar bear (''Ursus maritimus'') is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest extant bear specie ...

s, 42 ( Debby) *for horses, 62 *for Asian elephants, 86 The longest-lived vertebrates have been variously described as * Large parrots (macaws and cockatoos can live up to 80–100 years in captivity) * Koi (a Japanese species of fish, allegedly living up to 200 years, though generally not exceeding 50 – a specimen named

Hanako Hanako may refer to: People with the given name Hanako: * Hanako (given name) meaning Flower Child * Hanako, Princess Hitachi, Hanako Tsugaru, later Princess Hitachi of Japan * Hanako Takigawa (1988) Japanese gravure model, actress and TV talent ...

was reportedly 226 years old upon her death) * Tortoises ( Galápagos tortoise) (190 years) * Tuatara (a New Zealand reptile species, 100–200+ years) * Eels, the so-called

Brantevik Eel The Brantevik Eel () (Before 1859 - Before 7 August 2014), also known as Åle, was a European eel (''Anguilla anguilla'') that is believed to have lived for more than 150 years. The eel was released into a well in the town of Brantevik, Sweden ...

(Swedish: Branteviksålen) is thought to have lived in a water well in southern Sweden since 1859, which makes it over 150 years old. It was reported that it had died in August 2014 at an age of 155. * Whales (

bowhead whale The bowhead whale (''Balaena mysticetus'') is a species of baleen whale belonging to the family Balaenidae and the only living representative of the genus ''Balaena''. They are the only baleen whale endemic to the Arctic and subarctic waters, ...

) (''Balaena mysticetus'' about 200 years)—Although this idea was unproven for a time, recent research has indicated that bowhead whales recently killed still had harpoons in their bodies from about 1890, which, along with analysis of

amino acids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

, has indicated a maximum life span of "177 to 245 years old". * Greenland sharks are currently the vertebrate species with the longest known lifespan. * An examination of 28 specimens in one study published in 2016 determined by

radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was dev ...

that the oldest of the animals that they sampled had lived for about 392 ± 120 years (a minimum of 272 years and a maximum of 512 years). The authors further concluded that the species reaches sexual maturity at about 150 years of age. Invertebrate species which continue to grow as long as they live (''e.g.,'' certain clams, some coral species) can on occasion live hundreds of years: *A bivalve mollusk ('' Arctica islandica'') (aka " Ming", lived 507±2 years.)

Exceptions

*Some jellyfish species, including '' Turritopsis dohrnii'', ''Laodicea undulata'', and ''Aurelia'' sp.1, are able to revert to the polyp stage even after reproducing (so-called reversible life cycle), rather than dying as in other jellyfish. Consequently, these species are considered

biologically immortal Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, ...

and have no maximum lifespan. *There may be no natural limit to the ''Hydra'''s life span, but it is not yet clear how to estimate the age of a specimen. * Flatworms, or Platyhelminthes, are known to be "almost immortal" as they have a great regeneration capacity, continuous growth and binary fission type cellular division. * Lobsters are sometimes said to be

because they do not seem to slow down, weaken, or lose fertility with age. However, due to the energy needed for moulting, they cannot live indefinitely.

In plants

Plants are referred to as annuals which live only one year,

biennials A biennial plant is a flowering plant that, generally in a temperate climate, takes two years to complete its biological life cycle. Life cycle In its first year, the biennal plant undergoes primary growth, during which its vegetative structures ...

which live two years, and perennials which live longer than that. The longest-lived perennials, woody-stemmed plants such as trees and bushes, often live for hundreds and even thousands of years (one may question whether or not they may die of old age). A giant sequoia, General Sherman is alive and well in its third millennium. A Great Basin Bristlecone Pine called Methuselah is years old. Another Bristlecone Pine called Prometheus was a little older still, showing 4,862 years of growth rings. The exact age of Prometheus, however, remains unknown as it is likely that growth rings did not form every year due to the harsh environment in which it grew but it was estimated to be ~4,900 years old when it was cut down in 1964. The oldest known plant (possibly oldest living thing) is a clonal Quaking Aspen ('' Populus tremuloides'') tree colony in the Fishlake National Forest in Utah called Pando at about 16,000 years.

Lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Rhizocarpon geographicum'' can live upwards of 10,000 years.

Increasing maximum life span

"Maximum life span" here means the mean life span of the most long-lived 10% of a given cohort. Caloric restriction has not yet been shown to break mammalian world records for longevity.

Rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...

mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

, and hamsters experience maximum life-span extension from a diet that contains all of the nutrients but only 40–60% of the calories that the animals consume when they can eat as much as they want.

Mean life span Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...

is increased 65% and maximum life span is increased 50%, when caloric restriction is begun just before puberty. For fruit flies 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. A few transgenic strains of mice have been created that have maximum life spans greater than that of wild-type or laboratory mice. The Ames and Snell mice, which have mutations in pituitary transcription factors and hence are deficient in Gh, LH, TSH, and secondarily IGF1, have extensions in maximal lifespan of up to 65%. To date, both in absolute and relative terms, these Ames and Snell mice have the maximum lifespan of any mouse not on caloric restriction (see below on GhR). Mutations/knockout of other genes affecting the GH/IGF1 axis, such as Lit, Ghr and Irs1 have also shown extension in lifespan, but much more modest both in relative and absolute terms. The longest lived laboratory mouse ever was a Ghr knockout mouse, which lived to ≈1800 days in the lab of Andrzej Bartke at Southern Illinois University. The maximum for normal B6 mice under ideal conditions is 1200 days. Most biomedical gerontologists believe that

biomedical Biomedicine (also referred to as Western medicine, mainstream medicine or conventional medicine)

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

engineering will eventually extend maximum lifespan and even bring about rejuvenation. Anti-aging drugs are a potential tool for extending life. Aubrey de Grey, a theoretical gerontologist, has proposed that aging can be reversed by

strategies for engineered negligible senescence Strategies for engineered negligible senescence (SENS) is a range of proposed regenerative medical therapies, either planned or currently in development, for the periodic repair of all age-related damage to human tissue. These therapies have the u ...

. De Grey has established The Methuselah Mouse Prize to award money to researchers who can extend the maximum life span of mice. So far, three Mouse Prizes have been awarded: one for breaking longevity records to Dr. Andrzej Bartke of Southern Illinois University (using GhR knockout mice); one for late-onset rejuvenation strategies to Dr. Stephen Spindler of the University of California (using caloric restriction initiated late in life); and one to Dr. Z. Dave Sharp for his work with the pharmaceutical rapamycin.

Correlation with DNA repair capacity

Accumulated DNA damage appears to be a limiting factor in the determination of maximum life span. The theory that DNA damage is the primary cause of aging, and thus a principal determinant of maximum life span, has attracted increased interest in recent years. This is based, in part, on evidence in human and mouse that inherited deficiencies in DNA repair genes often cause accelerated aging. There is also substantial evidence that DNA damage accumulates with age in mammalian tissues, such as those of the brain, muscle, liver and kidney (reviewed by Bernstein et al. and see DNA damage theory of aging and DNA damage (naturally occurring)). One expectation of the theory (that DNA damage is the primary cause of aging) is that among species with differing maximum life spans, the capacity to repair DNA damage should correlate with lifespan. The first experimental test of this idea was by Hart and Setlow who measured the capacity of cells from seven different mammalian species to carry out DNA repair. They found that nucleotide excision repair capability increased systematically with species longevity. This correlation was striking and stimulated a series of 11 additional experiments in different laboratories over succeeding years on the relationship of nucleotide excision repair and life span in mammalian species (reviewed by Bernstein and Bernstein). In general, the findings of these studies indicated a good correlation between nucleotide excision repair capacity and life span. The association between nucleotide excision repair capability and longevity is strengthened by the evidence that defects in nucleotide excision repair proteins in humans and rodents cause features of premature aging, as reviewed by Diderich. Further support for the theory that DNA damage is the primary cause of aging comes from study of Poly ADP ribose polymerases (PARPs). PARPs are enzymes that are activated by DNA strand breaks and play a role in DNA base excision repair. Burkle et al. reviewed evidence that PARPs, and especially PARP-1, are involved in maintaining mammalian longevity. The life span of 13 mammalian species correlated with poly(ADP ribosyl)ation capability measured in mononuclear cells. Furthermore, lymphoblastoid cell lines from peripheral blood lymphocytes of humans over age 100 had a significantly higher poly(ADP-ribosyl)ation capability than control cell lines from younger individuals.

Research data

* A comparison of the heart

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

in rats (7-year maximum life span) and pigeons (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 * For

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s there is a direct relationship between mitochondrial membrane fatty acid saturation and maximum life span * Studies of the liver lipids of

s and a bird (pigeon) show an inverse relationship between maximum life span and number of double bonds * Selected species of birds and mammals show an inverse relationship between telomere rate of change (shortening) and maximum life span * Maximum life span correlates negatively with

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

enzyme levels and free-radicals production and positively with rate of DNA repair * Female mammals express more Mn−SOD and glutathione peroxidase antioxidant enzymes than males. This has been hypothesized as the reason they live longer However, mice entirely lacking in glutathione peroxidase 1 do not show a reduction in lifespan. * The maximum life span of transgenic mice has been extended about 20% by overexpression of human

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...

targeted to mitochondria * A comparison of 7 non-primate mammals (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 * A study of 8 non-primate mammals showed an inverse correlation between maximum life span and oxidative damage to mtDNA (

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

) in heart & brain * A study of several species of mammals and a bird (pigeon) indicated a linear relationship between oxidative damage to protein and maximum life span * There is a direct correlation between DNA repair and maximum life span for

ian species * 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 * Overexpression of the enzyme which synthesizes glutathione in long-lived transgenic ''Drosophila'' (fruit-flies) extended maximum lifespan by nearly 50% * A mutation in the age−1 gene of the

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

worm ''

Caenorhabditis elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (ro ...

'' increased

65% and maximum life span 110%. However, the degree of lifespan extension in relative terms by both the age-1 and daf-2 mutations is strongly dependent on ambient temperature, with ≈10% extension at 16 °C and 65% extension at 27 °C. * Fat-specific Insulin Receptor

KnockOut A knockout (abbreviated to KO or K.O.) is a fight-ending, winning criterion in several full-contact combat sports, such as boxing, kickboxing, muay thai, mixed martial arts, karate, some forms of taekwondo and other sports involving striking, a ...

(FIRKO) mice have reduced fat mass, normal calorie intake and an increased maximum life span of 18%. * The capacity of mammalian species to detoxify the carcinogenic chemical

benzo(a)pyrene Benzo 'a''yrene (B''a''P or B ) is a polycyclic aromatic hydrocarbon and the result of incomplete combustion of organic matter at temperatures between and . The ubiquitous compound can be found in coal tar, tobacco smoke and many foods, espec ...

to a water-soluble form also correlates well with maximum life span. * Short-term induction of oxidative stress due to calorie restriction increases life span in ''Caenorhabditis elegans'' by promoting stress defense, specifically by inducing an enzyme called catalase. As shown by

Michael Ristow Michael Ristow (b April 24, 1967) is a German medical researcher who has published influential articles on biochemical aspects of mitochondrial metabolism and particularly the possibly health-promoting role of reactive oxygen species in diseases ...

and co-workers nutritive antioxidants completely abolish this extension of life span by inhibiting a process called mitohormesis.

References

External links

Anage Database

Informational website on the biology of aging

{{DEFAULTSORT:Maximum Life Span Actuarial science Senescence