Longevity is long life or existence. Reflections on longevity have usually gone beyond acknowledging the basic shortness of human life and included thinking about, and conceiving, methods to extend life (indefinitely). Longevity has been a topic not only for the scientific community but also for writers of travel, science fiction and utopian novels. The record human lifespan that has been authenticated is the 122 years 164 days of Jeanne Calment, 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.

Different people have different lifestyles. But it appears that it matters most where in the world (rather than how) you live. Health care and hygiene seem to influence life expectancy more than any other factor (from the CIA World Fact Book):

• First World: 77-81 years
• Second World: 65-77 years
• Third World: 35-60 years

Tobacco smoking is generally accepted to significantly affect longevity, and is one of the main statistical factors explaining differences in life expectancy between advanced nations. This may be offset by other factors; Japan, a country with a high rate of tobacco consumption, has the highest life expectancy in the world (80.91 years, CIA Fact Book 2002). Hong Kong, a dense 7 million people city with constant stress, follows Japan closely (79.8 years, CIA Fact Book 2002).

Food and lifestyle make rather a small difference (all from CIA World Fact Book 2002):

• USA: 77.4 years
• UK: 77.99 years
• Germany: 77.78 years
• France: 79.05 years
• Italy: 79.25 years
• Australia: 80 years

Future

It is believed by some that life expectancy in First World countries will have risen to 100 years by 2030, and to 120 years by 2060. However, the mainstream view (such as the US Census Bureau) is that life expectancy will be in the mid-80s by the year 2050 (up from 77 today) and 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 USA would have 5.3 million people aged over 100 in 2100.

Longevity in fiction

• James Hilton: Lost Horizon
• P.D. James: The Children of Men
• James L. Halperin: The Truth Machine
• John Wyndham: Trouble with Lichen
• Robert A. Heinlein: Time Enough for Love, Methuselah's Children, and others.
• Arthur C. Clarke: 2001: A Space Odyssey
• David Brin & Gregory Benford: Heart of the Comet
• Kim Stanley Robinson's Mars trilogy
• Roger Zelazny: This Immortal
• J. K. Rowling: Harry Potter and the Philosopher's Stone (The Philosopher's Stone and Nicholas Flamel)
• J. R. R. Tolkien: The Lord of the Rings (Aragorn, Bilbo and Gollum)

See also

• List of centenarians
• List of supercentenarians
• Methuselah
• Longevity myths
• Senescence (aging)
• Immortality
• Life extension
• Caloric restriction
• Tai Chi Chuan
• Bristlecone pine
• Resveratrol