longevity

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longevity

[lon-jev-i-tee, lawn-]

longevity, term denoting the length or duration of the life of an animal or plant, often used to indicate an unusually long life. The average human life-span of threescore and ten years cited in the Bible has been attained only in recent years in areas of the world where man has been largely freed from disease and social and economic disadvantages. In the period around the American Revolution, the average life span was less than 35 years. By 1920, in the United States, the average life span had risen to 54 years; and by 1992 the median life span was 75.8 years. Studies indicate that females are likely to live longer than males. Shigechiyo Izumi of Japan, the longest-lived person authenticated, lived 120 years. The whale averages 60 years. The eagle and the swan have the longest lives among birds; of the fishes, the carp and pike are believed to live as long as 150 years. Among plants, the bristlecone pine of California has the greatest longevity, over 4,600 years. See geriatrics.

The Columbia Electronic Encyclopedia Copyright © 2004.
Licensed from Columbia University Press

life span

Time between birth and death. It ranges from a mayfly's day to certain trees' thousands of years. Its limit appears to depend on heredity, but such factors as (in humans) disease, natural disasters, war, diet, and habits such as smoking reduce it. Maximum life span is theoretical; more meaningful is average life span, which life-insurance companies and actuaries analyze and tabulate. Long-lived progenitors tend to beget long-lived descendants. A very-low-calorie diet appears to prolong life. Reduced infant mortality and improved sanitation and nutrition account for much of the increase since circa 1800—from about 35 to over 70 years in most industrialized countries. The oldest well-documented age reached by a human is 122 years.

Learn more about life span with a free trial on Britannica.com.

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

Longevity

The word longevity is sometimes used as a synonym for "life expectancy" in demography. However, this is not the most popular or accepted definition. For the general public as well as writers, the word generally connotes 'long life', especially when it concerns someone or something lasting longer than expected (an 'ancient tree', for example).

Reflections on longevity have usually gone beyond acknowledging the basic shortness of human life and have included thinking about methods to extend life. Longevity has been a topic not only for the scientific community but also for writers of travel, science fiction and utopian novels. There are many difficulties in authenticating the longest human lifespan ever, due to inaccurate birth statistics; though fiction, legend, and mythology have proposed or claimed vastly longer lifespans in the past or future and longevity myths frequently allege them to exist in the present.

A life annuity is a form of longevity insurance.

History

Longevity according to the psalms of the Bible was estimated on average to be "threescore and ten", that is 70 years, and "by reason of strength be extended to fourscore", that is 80 years. In addition, Solon, the famous lawgiver of Ancient Greece, in his dialogue with Croesus stated 70 as the allotted length of life for man. The longest living person as recorded in the Old Testament was Methuselah, who was said to have lived nearly a millennium.

There are many organizations dedicated to exploring the causes behind aging, ways to prevent aging, and ways to reverse aging. Despite the fact that it is human nature not to wish to surrender to old age and death, a few organizations are against antiaging because they believe it sacrifices the best interests of the new generation and/or that it is unnatural and/or unethical. Others are dedicated to it, seeing it as a form of transhumanism and the pursuit of immortality. Even among those who do not wish for eternal life, longevity may be desired to experience more of life or to provide a greater contribution to humanity.

A remarkable statement mentioned by Diogenes Laertius (c. 250) is the earliest (or at least one of the earliest) references about plausible centenarian longevity given by a scientist, the astronomer Hipparchus of Nicea (c.185—c.120 B.C.), who, according to the doxographer, assured that the philosopher Democritus of Abdera (c.470/460—c.370/360 B.C.) lived 109 years. All other accounts given by the ancients about the age of Democritus appear to, without giving any specific age, agree on the fact that the philosopher lived over 100 years. This is a possibility that turns out to be likely, given the fact that many ancient Greek philosophers are thought to have lived over the age of 90 (e.g., Xenophanes of Colophon, c.570/565—c.475/470 B.C., Pyrrho of Ellis, c.360—c.270 B.C., Eratosthenes of Cirene c.285—c.190 B.C., etc.) and because of the difference that the case of Democritus evidences from the case of, for example, Epimenides of Crete (VII, VI centuries B.C.), who is said to have lived 154, 157 or 290 years, as has been said about countless elders even during the last centuries as well as in the present time. These cases are not verifiable by modern means.

Present life expectancies around the world

Various factors contribute to an individual's longevity. Significant factors in life expectancy include gender, genetics, access to health care, hygiene, diet and nutrition, exercise, lifestyle, and crime rates. Below is a list of life expectancies in different types of countries:

First World: . . . 77-83 years (e.g. Canada: 80.1 years, 2005 est)
Third World:. . . 35-60 years (e.g. Mozambique: 40.3 years, 2005 est)

Population longevities can be seen as increasing due to increases in life expectancies around the world:

Spain:. . . . . 81.02 years in 2002, 82.31 years in 2005
Australia: . . 80 years in 2002, 80.39 years in 2005
Italy:. . . . . . 79.25 years in 2002, 79.68 years in 2005
France: . . . .79.05 years in 2002, 79.60 years in 2005
Germany: . . 77.78 years in 2002, 78.65 years in 2005
UK: . . . . . . 77.99 years in 2002, 78.4 years in 2005
USA: . . . . . 77.4 years in 2002, 77.7 years in 2005

The current validated longevity records can be found in the list of supercentenarians. Notable individuals include:

Jeanne Calment (1875-1997, 122 years and 164 days) — the oldest person in history whose age has been verified by modern documentation. This defines the human lifespan, which is set by the oldest documented individual who ever lived.
Shigechiyo Izumi (1865-1986, 120 years 237 days, disputed) — the oldest male ever recognized by the Guinness Book of World Records; this is widely questioned by scholars, who believe that conflation of dates has occurred and this has compromised the authenticity of Izumi's age.
Christian Mortensen (1882-1998, 115 years 252 days) — the oldest male widely accepted by scholars.

Exceptions: Populations from developing world with high life expectancy

Some populations have reputation of producing unusual number of individuals with exceptionally high ages, for example:

Okinawans,
people from the mountains of Pakistan the Hunza,
the inhabitants from the high mountain valley of Vilcabamba in South America,
inhabitants of some regions in the Caucasus mountains.

Religion

The Bible contains many accounts of long-lived humans, the oldest being Methuselah living to be 969 years old (). Today some maintain that the unusually high longevity of Biblical patriarchs are the result of an error in translation: lunar cycles were mistaken for the solar ones, and that the actual ages being described would have been 12.4 times less (a lunar cycle being 29.5 days). This makes Methuselah's age only 78. This rationalization, however, seems doubtful too since patriarchs such as Mahalalel and Enoch were said to have become fathers after 65 "years". If the lunar cycle claim were accepted this would translate to an age of about 5 years and 3 months.

One claim of Christian scholars is that the life span of humans has changed; that originally man was to have everlasting life, but due to man's sin, God progressively shortened man's life in the "four falls of mankind" — first to less than 1000 years, then to under 500, 200, and eventually 120 years. After those long living people died around the time of the Biblical Flood, God decided that humans would not be permitted to live more than 120 years However, since later biblical figures (and more recent people) such as Sarah lived for longer than that, 120 years should be considered the "usual" upper limit to man's lifespan. Some individuals can live slightly longer than that.

It has been hypothesized that there is a trade-off between cancerous tumor suppression and tissue repair capacity, and that by lengthening telomeres we might slow aging and in exchange increase vulnerability to cancer (Weinstein and Ciszek, 2002). Experimentation with telomeres on worms has yielded increased worm life spans by about 20% (Joeng et al., 2004). Even if further study shows that telomeres specifically are not tied to aging, the concept that some sort of DNA damage can cause genetically accelerated aging cannot be abandoned, thus providing a rational explanation for longevity and a subsequent reduction of longevity post-flood.

Many cultures like the Sumerians and Indus Valley also document groups of people who have lived for hundreds of years.

Furthermore, starting with reformers John Calvin and Martin Luther, an alternative explanation has arisen: 120 years would not refer to man's lifespan but to the amount of time left before the flood.

A more commonly accepted explanation is that such stories are longevity myths; age exaggeration tends to be greater in "mythical" periods in many cultures; the early emperors of Japan or China often ruled for more than a century, according to tradition. With the advent of modern accountable record-keeping, age claims fell to realistic levels. Even later in the Bible King David died at 70 years; other kings in their 30s, 40s, and 50s.

Future

The mainstream view on the future of longevity, such as the US Census Bureau, is that life expectancy in the United States will be in the mid 80s by 2050 (up from 77.85 in 2006) and will top out eventually in the low 90s, barring major scientific advances that can change the rate of human aging itself, as opposed to merely treating the effects of aging as is done today. The Census Bureau also predicted that the United States would have 5.3 million people aged over 100 in 2100.

Recent increases in the rates of lifestyle diseases, such as obesity, diabetes, hypertension, and heart disease, may however drastically slow or reverse this trend toward increasing life expectancy in the developed world.

Oeppen and Vaupel (see Science:1029, 2002) have observed that since 1840 record life expectancy has risen linearly for men and women, albeit more slowly for men. For women the increase has been almost three months per year. In light of steady increase, without any sign of limitation, the suggestion that life expectancy will top out must be treated with caution. Oeppen and Vaupel observe that experts who assert that "life expectancy is approaching a ceiling ... have repeatedly been proven wrong." It is thought that life expectancy for women has increased more dramatically due to the considerable advances in medicine related to childbirth.

Some argue that molecular nanotechnology will greatly extend human lifespans. If the rate of increase of lifespan can be raised with these technologies to a level of not three months per year, but twelve months per year, we will have achieved effective immortality. This is the goal of radical life extension.

Non-human biological longevity

Living:

Methuselah — 4,800-year-old bristlecone pine in the White Mountains of California, the oldest currently living organism known.
Cheeta — a 76-year-old chimpanzee, the oldest chimpanzee known.

Dead:

A bristlecone pine nicknamed "Prometheus", felled in the Great Basin National Park in Nevada in 1964, found to be about 4900 years old, is the longest-lived single organism known.
A quahog clam (Arctica islandica), dredged from off the coast of Iceland in 2007, was found to be from 400 to 410 years old, the oldest animal documented. Other clams of the species have been recorded as living up to 374 years.
Tu'i Malila, a radiated tortoise presented to the Tongan royal family by Captain Cook, lived for over 185 years. It is the oldest documented reptile. Adwaitya, an Aldabra Giant Tortoise, may have lived for up to 250 years.
A Bowhead Whale killed in a hunt was found to be approximately 211 years old (possibly up to 245 years old), the longest lived mammal known.
Lamellibrachia luymesi, a deep-sea cold-seep tubeworm, is estimated to reach ages of over 250 years based on a model of its growth rates.
Hanako (Koi Fish) was the longest-lived vertebrate ever recorded at 215 years.