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May 24, 2012 |
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The word " longevity " is sometimes used as a synonym for " life expectancy" in demography or to connote "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 brevity 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 life span ever by modern verification standards, owing to inaccurate or incomplete birth statistics. Fiction, legend, and folklore have proposed or claimed life spans in the past or future vastly longer than those verified by modern standards, and longevity narratives and unverified longevity claims frequently speak of their existence in the present. A life annuity is a form of longevity insurance. A remarkable statement mentioned by Diogenes Laertius (c. 250 AD) 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 BC), who, according to the doxographer, was assured that the philosopher Democritus of Abdera (c. 470/460 ??? c. 370/360 BC) lived 109 years. All other accounts given by the ancients about the age of Democritus appear, without giving any specific age, to agree that the philosopher lived over 100 years. This possibility is likely, given 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 BC, Pyrrho of Ellis, c. 360 ??? c. 270 BC, Eratosthenes of Cirene, c. 285 ??? c. 190 BC, etc.). The case of Democritus is different from the case of, for example, Epimenides of Crete (7th, 6th centuries BC), 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. 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:
Population longevities can be seen as increasing due to increases in life expectancies around the world:
The Gerontology Research Group validates current longevity records by modern standards, and maintains a list of supercentenarians; many other unvalidated longevity claims exist. Record-holding individuals include:
Evidence-based studies indicate that longevity is based on two major factors, genetics (fate) and lifestyle choices. Twin studies , have estimated that approximately 20-30% of an individual???s lifespan is related to genetics, the rest is due to individual behaviors and environmental factors which can be modified. Study of the regions of the world known as blue zones , where people commonly live active lives past 100 years of age, have shown that longevity is related to a healthy social and family life, not smoking, eating a plant-based diet, frequent consumption of legumes and nuts, and engaging in regular physical activity. In another well-designed cohort study , the combination of a plant based diet, frequent consumption of nuts, regular physical activity, normal BMI, and not smoking accounted for differences up to 10 years in life expectancy. The Alameda County Study discovered three additional lifestyle characteristics that promote longevity: limiting alcohol consumption, sleeping 7 to 8 hours per night, and not snacking (eating between meals). Longevity traditions are traditions about long-lived people (generally supercentenarians), and practices that have been believed to confer longevity. The Fountain of Youth reputedly restores the youth of anyone who drinks of its waters. The New Testament, following older Jewish tradition, attributes healing to the Pool of Bethesda when the waters are "stirred" by an angel. After the death of Juan Ponce de Le??n, Gonzalo Fern??ndez de Oviedo wrote in Historia General y Natural de las Indias (1535) that Ponce de Le??n was looking for the waters of Bimini to cure his aging. Traditions that have been believed to confer greater human longevity also include alchemy, such as that attributed to Nicolas Flamel. In the modern era, the Okinawa diet has some reputation of linkage to exceptionally high ages. More recent longevity claims are subcategorized by many editions of Guinness World Records into four groups: "In late life, very old people often tend to advance their ages at the rate of about 17 years per decade .... Several celebrated super-centenarians (over 110 years) are believed to have been double lives (father and son, relations with the same names or successive bearers of a title) .... A number of instances have been commercially sponsored, while a fourth category of recent claims are those made for political ends ...." Robert L. Ripley regularly reported supercentenarian claims in Ripley's Believe It or Not!, usually citing his own reputation as a fact-checker to claim reliability. The U.S. Census Bureau view on the future of longevity 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. The United Nations has also made projections far out into the future, up to 2300, at which point it projects that life expectancies in most developed countries will be between 100 and 106 years and still rising, though more and more slowly than before. These projections also suggest that life expectancies in poor countries will still be less than those in rich countries in 2300, in some cases by as much as 20 years. The UN itself mentioned that gaps in life expectancy so far in the future may well not exist, especially since the exchange of technology between rich and poor countries and the industrialization and development of poor countries may cause their life expectancies to converge fully with those of rich countries long before that point, similarly to the way life expectancies between rich and poor countries have already been converging over the last 60 years as better medicine, technology, and living conditions became accessible to many people in poor countries. The UN has warned that these projections are uncertain, and caution that any change or advancement in medical technology could invalidate their projections. Recent increases in the rates of lifestyle diseases, such as obesity, diabetes , hypertension, and heart disease, may drastically slow or reverse this trend toward increasing life expectancy in the developed world. 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. Scientists 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 owing to the considerable advances in medicine related to childbirth. Some argue that molecular nanotechnology will greatly extend human life spans. If the rate of increase of life span can be raised with these technologies to a level of twelve months increase per year, this is defined as effective biological immortality and is the goal of radical life extension. Currently living :
Currently nonliving :
*Longevity This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "longevity".
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