Maximum life span
Encyclopedia
Maximum life span is a measure of the maximum amount of time one or more members of a population has been observed to survive between birth
and death
.
Most living species have at least one upper limit on the number of times cells can divide. For humans, this is called the Hayflick limit
, although number of cell divisions does not strictly control lifespan (non-dividing cells and dividing cells lived 120 years in the oldest known human
).
. 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 is in contrast with mean life span (average life span 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".
whose dates of birth and death were verified to the modern norms of Guinness World Records
and the Gerontology Research Group
was Jeanne Calment
, a French
woman who lived to 122. The maximum (recorded) life span for humans has increased from 103 in 1798 to 110 years in 1898, 115 years in 1990, and 122.45 years since Calment's death in 1997 (See List of the verified oldest people and List of verified supercentenarians who died before 1980.), among steady improvements in overall life expectancy
. Reduction of infant mortality has accounted for most of this increased average longevity
, but since the 1960s mortality rate
s 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." 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.
No fixed theoretical limit to human longevity is apparent today. "A fundamental question in aging research is whether humans and other species possess an immutable life-span limit." "The assumption that the maximum human life span is fixed has been justified [but] is invalid in a number of animal models and ... may become invalid for humans as well." 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.
s and squirrel
s rarely live to their maximum life span, usually dying of accident
s, 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
.
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 or have effective defenses against predation, such as bird flight, tortoise shells, porcupine quills, or large primate brains.
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:
The longest-lived vertebrates have been variously described as
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:
s are referred to as annuals
which live only one year, biennials
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 4,841 years old (as of 2010) and the Bristlecone Pine called Prometheus
was a little older still, at least 4,844 years (and possibly as old as 5,000 years), when it was cut down in 1964. The oldest known plant (possibly oldest living thing) is a creosote bush (Larrea tridentata) in the Mojave Desert called King Clone
at about 11,700 years.
is calorie restriction
with adequate nutrition. "Maximum life span" here means the mean life span of the most long-lived 10% of a given cohort, as caloric restriction has not yet been shown to break mammalian world records for longevity. Rat
s, mice
, and hamster
s experience maximum life-span extension from a diet that contains 40–60% of the calories (but all of the required nutrients) that the animals consume when they can eat as much as they want. Mean life span 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 species 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 on caloric restriction, which lived to ~1800 days (maximum for normal B6 mice under ideal conditions is 1200 days) in the lab of A. Bartke at Southern Illinois University
.
Most biomedical gerontologists
(gerontologists who search for ways to extend maximum life span) believe that biomedical molecular engineering
will eventually extend maximum lifespan and even bring about rejuvenation
.
Aubrey de Grey
, a theoretical gerontologist, has proposed that the damage called aging can be reversed by SENS (Strategies for Engineered Negligible Senescence). Dr. de Grey has established The Methuselah Mouse Prize to award money to researchers who can extend the maximum life span of mice. A. Bartker collected the prize for the GhR knockout mouse and Speakman collected the prize for extending the maximum lifespan of an adult mouse, using caloric restriction initiated late in life.
Birth
Birth is the act or process of bearing or bringing forth offspring. The offspring is brought forth from the mother. The time of human birth is defined as the time at which the fetus comes out of the mother's womb into the world...
and death
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
.
Most living species have at least one upper limit on the number of times cells can divide. For humans, this is called the Hayflick limit
Hayflick limit
The Hayflick limit is the number of times a normal cell population will divide before it stops, presumably because the telomeres reach a critical length....
, although number of cell divisions does not strictly control lifespan (non-dividing cells and dividing cells lived 120 years in the oldest known human
Oldest people
This is a list of tables of the verified oldest people in the world in ordinal rank, such as oldest person or oldest man. In these tables, a supercentenarian is considered 'verified' if his or her claim has been validated by an international body that specifically deals in longevity research, such...
).
Definition
In animal studies, maximum life span is often taken to be the mean life span of the most long-lived 10% of a given cohortCohort study
A cohort study or panel study is a form of longitudinal study used in medicine, social science, actuarial science, and ecology. It is an analysis of risk factors and follows a group of people who do not have the disease, and uses correlations to determine the absolute risk of subject contraction...
. By another definition, however, maximum life span corresponds to the age at which the oldest known member of a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
or experimental group has died. Calculation of the maximum life span in the latter sense depends upon initial sample size.
Maximum life span is in contrast with mean life span (average life span or life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...
). Mean life span varies with susceptibility to disease, accident
Accident
An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...
, suicide
Suicide
Suicide is the act of intentionally causing one's own death. Suicide is often committed out of despair or attributed to some underlying mental disorder, such as depression, bipolar disorder, schizophrenia, alcoholism, or drug abuse...
and homicide
Murder
Murder is the unlawful killing, with malice aforethought, of another human being, and generally this state of mind distinguishes murder from other forms of unlawful homicide...
, whereas maximum life span is determined by "rate of aging".
In humans
The longest-living personOldest people
This is a list of tables of the verified oldest people in the world in ordinal rank, such as oldest person or oldest man. In these tables, a supercentenarian is considered 'verified' if his or her claim has been validated by an international body that specifically deals in longevity research, such...
whose dates of birth and death were verified to the modern norms of Guinness World Records
Guinness World Records
Guinness World Records, known until 2000 as The Guinness Book of Records , is a reference book published annually, containing a collection of world records, both human achievements and the extremes of the natural world...
and the Gerontology Research Group
Gerontology Research Group
The Gerontology Research Group was started in 1990, and is a global eGroup of researchers in gerontology, some of who also meet monthly at UCLA in Los Angeles, California. The primary function of the group is to further gerontology research, with the objective of reversing or retarding aging...
was Jeanne Calment
Jeanne Calment
Jeanne Louise Calment was a French supercentenarian who had the longest confirmed human life span in history, living to the age of . She lived in Arles, France, for her entire life, and outlived both her daughter and grandson. She became especially well known from the age of 113, when the...
, a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
woman who lived to 122. The maximum (recorded) life span for humans has increased from 103 in 1798 to 110 years in 1898, 115 years in 1990, and 122.45 years since Calment's death in 1997 (See List of the verified oldest people and List of verified supercentenarians who died before 1980.), among steady improvements in overall life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...
. Reduction of infant mortality has accounted for most of this increased average longevity
Longevity
The word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....
, but since the 1960s mortality rate
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
s among those over 80 years have decreased by about 1.5% per year. "The progress being made in lengthening lifespans and postponing senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
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 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.
No fixed theoretical limit to human longevity is apparent today. "A fundamental question in aging research is whether humans and other species possess an immutable life-span limit." "The assumption that the maximum human life span is fixed has been justified [but] is invalid in a number of animal models and ... may become invalid for humans as well." Studies in the biodemography of human longevity
Biodemography of human longevity
Biodemography is a multidisciplinary approach, integrating biological knowledge with demographic research on human longevity and survival...
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.
In other animals
Small animals such as birdBird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s and squirrel
Squirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
s rarely live to their maximum life span, usually dying of accident
Accident
An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...
s, disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
or predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
. Grazing animals accumulate wear and tear to their teeth to the point where they can no longer eat, and they die of starvation
Starvation
Starvation is a severe deficiency in caloric energy, nutrient and vitamin intake. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, death...
.
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 or have effective defenses against predation, such as bird flight, tortoise shells, porcupine quills, or large primate brains.
The differences in life span between species demonstrate the role of genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
in determining maximum life span ("rate of aging"). The records (in years) are these:
- for common house mouseHouse mouseThe house mouse is a small rodent, a mouse, one of the most numerous species of the genus Mus.As a wild animal the house mouse mainly lives associated with humans, causing damage to crops and stored food....
, 4 - for Norway rat 7
- for dogDogThe domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, 29, in Australia (See List of oldest dogs) - for catCatThe cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, 38 - for polar bearPolar BearThe polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...
s, 42 (DebbyDebby (polar bear)Debby was the world's oldest polar bear. She lived in the Assiniboine Park Zoo in Winnipeg. In August 2008, the Guinness Book of World Records certified her as not only the oldest polar bear, but one of the three oldest individuals ever recorded of all bear species.Debby was born in the Soviet...
) - for horses, 62
- for common chimpanzeeCommon ChimpanzeeThe common chimpanzee , also known as the robust chimpanzee, is a great ape. Colloquially, the common chimpanzee is often called the chimpanzee , though technically this term refers to both species in the genus Pan: the common chimpanzee and the closely related bonobo, formerly called the pygmy...
s, 71.4 - for Asian elephantAsian ElephantThe Asian or Asiatic elephant is the only living species of the genus Elephas and distributed in Southeast Asia from India in the west to Borneo in the east. Three subspecies are recognized — Elephas maximus maximus from Sri Lanka, the Indian elephant or E. m. indicus from mainland Asia, and E. m....
s, 86
The longest-lived vertebrates have been variously described as
- Macaws (A parrot that can live up to 80-100 years in captivity)
- koiKoior more specifically , are ornamental varieties of domesticated common carp that are kept for decorative purposes in outdoor koi ponds or water gardens....
(A Japanese species of fish, 200+ years, though generally not exceeding 25) Hanako was reportedly 226 years old upon her death. - Greenland SharkGreenland sharkThe Greenland shark, Somniosus microcephalus, also known as the sleeper shark, gurry shark, ground shark, grey shark, or by the Inuit languages name Eqalussuaq, is a large shark native to the waters of the North Atlantic Ocean around Greenland and Iceland. These sharks live farther north than any...
s (A species of shark native to the North Atlantic, believed to be about 200 years) - tortoiseTortoiseTortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
s (Galápagos tortoiseGalápagos tortoiseThe Galápagos tortoise or Galápagos giant tortoise is the largest living species of tortoise, reaching weights of over and lengths of over . With life spans in the wild of over 100 years, it is one of the longest-lived vertebrates...
) (190 years) - tuataraTuataraThe tuatara is a reptile endemic to New Zealand which, though it resembles most lizards, is actually part of a distinct lineage, order Sphenodontia. The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago. Their most recent common...
s (a New Zealand reptile species, 100-200+ years) - eelEelEels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
s, the so called Brantevik eel (Swedish: Branteviksålen) is thought to have lived in a water well in southern Sweden since 1859, which makes it over 150 years old. - whaleWhaleWhale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s (Bowhead WhaleBowhead WhaleThe bowhead whale is a baleen whale of the right whale family Balaenidae in suborder Mysticeti. A stocky dark-colored whale without a dorsal fin, it can grow to in length. This thick-bodied species can weigh to , second only to the blue whale, although the bowhead's maximum length is less than...
) (Balaena mysticetus about 200 years)
- Although this idea was unproven for a time, recent research has indicated that bowhead whaleBowhead WhaleThe bowhead whale is a baleen whale of the right whale family Balaenidae in suborder Mysticeti. A stocky dark-colored whale without a dorsal fin, it can grow to in length. This thick-bodied species can weigh to , second only to the blue whale, although the bowhead's maximum length is less than...
s recently killed still had harpoonHarpoonA harpoon is a long spear-like instrument used in fishing to catch fish or large marine mammals such as whales. It accomplishes this task by impaling the target animal, allowing the fishermen to use a rope or chain attached to the butt of the projectile to catch the animal...
s in their bodies from about 1890, which, along with analysis of amino acids, has indicated a maximum life span, stated as "the 211 year-old bowhead could have been from 177 to 245 years old". However, with the possible exception of the Bowhead whale, the claims of lifespans >100 year must be taken with some skepticism as they rely on conjecture (e.g. counting otoliths) rather than empirical, continuous documentation.
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 molluscBivalviaBivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
(Arctica islandicaArctica islandicaArctica islandica, commonly known as the ocean quahog, is an edible marine bivalve mollusk native to the North Atlantic ocean, which is harvested commercially...
) (aka "MingMing (clam)right|thumb|upright|One [[valve |valve]] of the shell of Ming, a clam estimated to be 405-410 years oldMing is the nickname given to a specimen of an ocean quahog clam, Arctica islandica, family Veneridae, and is the oldest living animal ever discovered.Judging by the annual growth rings on the...
" between 405–410 years old)
Exception
- One species of jellyfishJellyfishJellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
, Turritopsis nutriculaTurritopsis nutriculaTurritopsis nutricula, the immortal jellyfish, is a hydrozoan whose medusa, or jellyfish, form can revert to the polyp stage after becoming sexually mature. It is the only known case of a metazoan capable of reverting completely to a sexually immature, colonial stage after having reached sexual...
, reverts to a sexually immature stage after reproducing, rather than dying as in other jellyfish. Consequently the species is considered biologically immortalBiological immortalityBiological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
and has no maximum lifespan.
- There may be no natural limit to the Hydra'sHydra (genus)Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...
life span, but it is not yet clear how to estimate the age of a specimen.
In plants
PlantPlant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s are referred to as annuals
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
which live only one year, biennials
Biennial plant
A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots , then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming...
which live two years, and perennials
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous 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
General Sherman (tree)
The General Sherman is a giant sequoia tree located in the Giant Forest of Sequoia National Park in Tulare County, California. By volume, it is the largest known living single stem tree on Earth...
is alive and well in its third millennium
Millennium
A millennium is a period of time equal to one thousand years —from the Latin phrase , thousand, and , year—often but not necessarily related numerically to a particular dating system....
. A Great Basin Bristlecone Pine
Great Basin Bristlecone Pine
Pinus longaeva, the Great Basin Bristlecone Pine, is a long-living species of tree found in the higher mountains of the southwest United States. The species is one of three closely related trees known as bristlecone pines and is sometimes known as the Intermountain or Western bristlecone pine...
called Methuselah
Methuselah (tree)
Methuselah is a Great Basin Bristlecone Pine tree growing high in the White Mountains of Inyo County in eastern California. Its measured age of 4,842 years makes it the world's oldest known living non-clonal organism...
is 4,841 years old (as of 2010) and the Bristlecone Pine called Prometheus
Prometheus (tree)
Prometheus was the oldest known non-clonal organism, a Great Basin Bristlecone Pine tree growing near the tree line on Wheeler Peak in eastern Nevada, United States...
was a little older still, at least 4,844 years (and possibly as old as 5,000 years), when it was cut down in 1964. The oldest known plant (possibly oldest living thing) is a creosote bush (Larrea tridentata) in the Mojave Desert called King Clone
King Clone
King Clone is thought to be the oldest Creosote bush ring in the Mojave Desert is estimated to be 11,700 years old. It is considered one of the oldest living organisms on Earth...
at about 11,700 years.
Increasing maximum life span
Currently, the only (non-transgenic) method of increasing maximum life span that is recognized by biogerontologistsGerontology
Gerontology is the study of the social, psychological and biological aspects of aging...
is calorie restriction
Calorie restriction
Caloric restriction , or calorie restriction, is a dietary regimen that restricts calorie intake, where the baseline for the restriction varies, usually being the previous, unrestricted, intake of the subjects...
with adequate nutrition. "Maximum life span" here means the mean life span of the most long-lived 10% of a given cohort, as caloric restriction has not yet been shown to break mammalian world records for longevity. Rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s, mice
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
, and hamster
Hamster
Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....
s experience maximum life-span extension from a diet that contains 40–60% of the calories (but all of the required nutrients) that the animals consume when they can eat as much as they want. Mean life span is increased 65% and maximum life span is increased 50%, when caloric restriction is begun just before puberty
Puberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
.). For fruit flies
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
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 species 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 on caloric restriction, which lived to ~1800 days (maximum for normal B6 mice under ideal conditions is 1200 days) in the lab of A. Bartke at Southern Illinois University
Southern Illinois University
Southern Illinois University is a state university system based in Carbondale, Illinois, in the Southern Illinois region of the state, with multiple campuses...
.
Most biomedical gerontologists
Gerontology
Gerontology is the study of the social, psychological and biological aspects of aging...
(gerontologists who search for ways to extend maximum life span) believe that biomedical molecular engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
will eventually extend maximum lifespan and even bring about rejuvenation
Rejuvenation (aging)
Rejuvenation is the hypothetical reversal of the aging process.Rejuvenation is distinct from life extension. Life extension strategies often study the causes of aging and try to oppose those causes in order to slow aging...
.
Aubrey de Grey
Aubrey de Grey
Aubrey David Nicholas Jasper de Grey is an English author and theoretician in the field of gerontology, and the Chief Science Officer of the SENS Foundation. He is editor-in-chief of the academic journal Rejuvenation Research, author of The Mitochondrial Free Radical Theory of Aging and co-author...
, a theoretical gerontologist, has proposed that the damage called aging can be reversed by SENS (Strategies for Engineered Negligible Senescence). Dr. de Grey has established The Methuselah Mouse Prize to award money to researchers who can extend the maximum life span of mice. A. Bartker collected the prize for the GhR knockout mouse and Speakman collected the prize for extending the maximum lifespan of an adult mouse, using caloric restriction initiated late in life.
Research data concerning maximum life span
- A comparison of the heart mitochondria in rats (7-year maximum life span) and pigeons (35-year maximum life span) showed that pigeon mitochondria leak fewer free-radicalsRadical (chemistry)Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
than rat mitochondria, despite the fact that both animals have similar metabolic rate and cardiac output - For mammalMammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s there is a direct relationship between mitochondrial membrane fatty acid saturation and maximum life span - Studies of the liverLiverThe liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
lipidLipidLipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s of mammalMammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s and a bird (pigeon) show an inverse relationship between maximum life span and number of double bondDouble bondA double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...
s - Selected species of birds and mammals show an inverse relationship between telomereTelomereA telomere is a region of repetitive DNA sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos "end" and merοs "part"...
rate of change (shortening) and maximum life span - Maximum life span correlates negatively with antioxidantAntioxidantAn antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
enzymeEnzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
levels and free-radicalsRadical (chemistry)Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
production and positively with rate of DNA repairDNA repairDNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as UV light and radiation can cause DNA damage, resulting in as many as 1... - 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 transgenicGenetically modified organismA genetically modified organism or genetically engineered organism is an organism whose genetic material has been altered using genetic engineering techniques. These techniques, generally known as recombinant DNA technology, use DNA molecules from different sources, which are combined into one...
mice has been extended about 20% by overexpression of human catalaseCatalaseCatalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...
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 DNAMitochondrial DNAMitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
) 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 mammalMammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
ian species - DrosophilaDrosophilaDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
(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 glutathioneGlutathioneGlutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...
in long-lived transgenicGenetically modified organismA genetically modified organism or genetically engineered organism is an organism whose genetic material has been altered using genetic engineering techniques. These techniques, generally known as recombinant DNA technology, use DNA molecules from different sources, which are combined into one...
DrosophilaDrosophilaDrosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
(fruit-flies) extended maximum lifespan by nearly 50% - A mutation in the age−1 gene of the nematodeNematodeThe nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
worm Caenorhabditis elegansCaenorhabditis elegansCaenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
increased mean life span 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 KnockOutKnockout mouseA knockout mouse is a genetically engineered mouse in which researchers have inactivated, or "knocked out," an existing gene by replacing it or disrupting it with an artificial piece of DNA...
(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)pyreneBenzopyreneBenzo[a]pyrene, C20H12, is a five-ring polycyclic aromatic hydrocarbon whose metabolites are mutagenic and highly carcinogenic. Benzo[a]pyrene is listed as a Group 1 carcinogen by the IARC. It belongs to a class of polycyclic aromatic compounds known as benzopyrenes, which consist of a benzene...
to a water-soluble form also correlates well with maximum life span. - Short-term induction of oxidative stressOxidative stressOxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage...
due to calorie restrictionCalorie restrictionCaloric restriction , or calorie restriction, is a dietary regimen that restricts calorie intake, where the baseline for the restriction varies, usually being the previous, unrestricted, intake of the subjects...
increases life span in Caenorhabditis elegansCaenorhabditis elegansCaenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
by promoting stress defense, specifically by inducing an enzyme called catalase. As shown by Michael RistowMichael RistowMichael Ristow is a German medical researcher who has published influential articles on the metabolic basis of human diseases, including type 2 diabetes, obesity and cancer, as well as general aging processes...
and co-workers nutritive antioxidants completely abolish this extension of life span by inhibiting a process called mitohormesis.
See also
- AgeingAgeingAgeing or aging is the accumulation of changes in a person over time. Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline...
- American Aging AssociationAmerican Aging AssociationThe American Aging Association is a non-profit, tax-exempt biogerontology organization of scientists and laypeople dedicated to biomedical aging studies intended to slow the aging process. The abbreviation AGE is intended to be representative of the organization, even though it is not an acronym...
- Aubrey de GreyAubrey de GreyAubrey David Nicholas Jasper de Grey is an English author and theoretician in the field of gerontology, and the Chief Science Officer of the SENS Foundation. He is editor-in-chief of the academic journal Rejuvenation Research, author of The Mitochondrial Free Radical Theory of Aging and co-author...
- BiodemographyBiodemographyBiodemography is the science dealing with the integration of biology and demography.Biodemography is a new branch of human demography concerned with understanding the complementary biological and demographic determinants of and interactions between the birth and death processes that shape...
- Biological immortalityBiological immortalityBiological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
- Calorie restrictionCalorie restrictionCaloric restriction , or calorie restriction, is a dietary regimen that restricts calorie intake, where the baseline for the restriction varies, usually being the previous, unrestricted, intake of the subjects...
- Compression of morbidityCompression of morbidityThe compression of morbidity in public health is a hypothesis put forth by James Fries, professor of medicine at Stanford University School of Medicine...
- DNA damage theory of agingDNA damage theory of agingThe DNA damage theory of aging proposes that aging is a consequence of unrepaired DNA damage accumulation. Damage in this context includes chemical reactions that mutate DNA and/or interfere with DNA replication. Although both mitochondrial and nuclear DNA damage can contribute to aging, nuclear...
- Extreme longevity trackingExtreme longevity trackingExtreme longevity tracking is the tracing and recording of claims of exceptionally long human lives , as a branch of demography. Persons have been noted for tracking 'supercentenarians' for hundreds of years; some included quite famous persons noted in other fields...
- GerontologyGerontologyGerontology is the study of the social, psychological and biological aspects of aging...
- Hayflick limitHayflick limitThe Hayflick limit is the number of times a normal cell population will divide before it stops, presumably because the telomeres reach a critical length....
- Indefinite lifespanIndefinite lifespanIndefinite lifespan or, indefinite life extension, is a term used in the life extension movement to refer to the longevity of humans, and other life-forms, under conditions in which aging can be effectively and completely prevented and treated. Such individuals would still be susceptible to...
- Life expectancyLife expectancyLife expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...
- Life extensionLife extensionLife extension science, also known as anti-aging medicine, experimental gerontology, and biomedical gerontology, is the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan...
- List of long-living organisms
- LongevityLongevityThe word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....
- Methuselah Mouse Prize
- Michael RistowMichael RistowMichael Ristow is a German medical researcher who has published influential articles on the metabolic basis of human diseases, including type 2 diabetes, obesity and cancer, as well as general aging processes...
- Mitohormesis
- Oldest peopleOldest peopleThis is a list of tables of the verified oldest people in the world in ordinal rank, such as oldest person or oldest man. In these tables, a supercentenarian is considered 'verified' if his or her claim has been validated by an international body that specifically deals in longevity research, such...
- SenescenceSenescenceSenescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
- Strategies for Engineered Negligible Senescence (SENS)