Longevity may refer to especially long-lived members of a population, whereas life expectancy is defined statistically as the average number of years remaining at a given age. For example, a population's life expectancy at birth is the same as the average age at death for all people born in the same year (in the case of cohorts).
Longevity studies may involve putative 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. The legendary fountain of youth appeared in the work of the Ancient Greek historian Herodotus.
There are difficulties in authenticating the longest human life span, 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.
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: [1]
Population longevities are increasing as life expectancies around the world grow: [2] [3]
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: [4] [5] [6]
Evidence-based studies indicate that longevity is based on two major factors: genetics and lifestyle. [10]
Twin studies have estimated that approximately 20-30% of the variation in human lifespan can be related to genetics, with the rest due to individual behaviors and environmental factors which can be modified. [11] Although over 200 gene variants have been associated with longevity according to a US-Belgian-UK research database of human genetic variants [12] these explain only a small fraction of the heritability. [13]
Lymphoblastoid cell lines established from blood samples of centenarians have significantly higher activity of the DNA repair protein PARP (Poly ADP ribose polymerase) than cell lines from younger (20 to 70 year old) individuals. [14] The lymphocytic cells of centenarians have characteristics typical of cells from young people, both in their capability of priming the mechanism of repair after H2O2 sublethal oxidative DNA damage and in their PARP gene expression. [15] These findings suggest that elevated PARP gene expression contributes to the longevity of centenarians, consistent with the DNA damage theory of aging. [16]
In July 2020, scientists used public biological data on 1.75 m people with known lifespans overall and identified 10 genomic loci which appear to intrinsically influence healthspan, lifespan, and longevity – of which half have not been reported previously at genome-wide significance and most being associated with cardiovascular disease – and identified haem metabolism as a promising candidate for further research within the field. Their study suggests that high levels of iron in the blood likely reduce, and genes involved in metabolising iron likely increase healthy years of life in humans. [18] [17]
Longevity is a highly plastic trait, and traits that influence its components respond to physical (static) environments and to wide-ranging life-style changes: physical exercise, dietary habits, living conditions, and pharmaceutical as well as nutritional interventions. [19] [20] [21] A 2012 study found that even modest amounts of leisure time physical exercise can extend life expectancy by as much as 4.5 years. [22]
As of 2021, there is no clinical evidence that any dietary practice contributes to human longevity. [23] Although health can be influenced by diet, including the type of foods consumed, the amount of calories ingested, and the duration and frequency of fasting periods, [24] there is no good clinical evidence that fasting promotes longevity in humans, as of 2021 [update] . [23] [25] [26]
Calorie restriction is a widely researched intervention to assess effects on aging, defined as a sustained reduction in dietary energy intake compared to the energy required for weight maintenance. [23] [25] To ensure metabolic homeostasis, the diet during calorie restriction must provide sufficient energy, micronutrients, and fiber. [25] Some studies on rhesus monkeys showed that restricting calorie intake resulted in lifespan extension, while other animals studies did not detect a significant change. [23] [27] According to preliminary research in humans, there is little evidence that calorie restriction affects lifespan. [23] [25] There is a link between diet and obesity and consequent obesity-associated morbidity.
Four well-studied biological pathways that are known to regulate aging, and whose modulation has been shown to influence longevity are Insulin/IGF-1, mechanistic target of rapamycin (mTOR), AMP-activating protein kinase (AMPK), and Sirtuin pathways. [28] [29]
Autophagy plays a pivotal role in healthspan and lifespan extension. [29] [30]
In preindustrial times, deaths at young and middle age were more common than they are today. This is not due to genetics, but because of environmental factors such as disease, accidents, and malnutrition, especially since the former were not generally treatable with pre-20th-century medicine. Deaths from childbirth were common for women, and many children did not live past infancy. In addition, most people who did attain old age were likely to die quickly from the above-mentioned untreatable health problems. Despite this, there are several examples of pre-20th-century individuals attaining lifespans of 85 years or greater, including John Adams, Cato the Elder, Thomas Hobbes, Christopher Polhem, and Michelangelo. This was also true for poorer people like peasants or laborers.[ citation needed ] Genealogists will almost certainly find ancestors living to their 70s, 80s and even 90s several hundred years ago.
For example, an 1871 census in the UK (the first of its kind, but personal data from other censuses dates back to 1841 and numerical data back to 1801) found the average male life expectancy as being 44, but if infant mortality is subtracted, males who lived to adulthood averaged 75 years. The present life expectancy in the UK is 77 years for males and 81 for females, while the United States averages 74 for males and 80 for females.
Studies have shown that black American males have the shortest lifespans of any group of people in the US, averaging only 69 years (Asian-American females average the longest). [31] This reflects overall poorer health and greater prevalence of heart disease, obesity, diabetes, and cancer among black American men.
Women normally outlive men. Theories for this include smaller bodies that place lesser strain on the heart (women have lower rates of cardiovascular disease) and a reduced tendency to engage in physically dangerous activities. [32] Conversely, women are more likely to participate in health-promoting activities. [33] The X chromosome also contains more genes related to the immune system, and women tend to mount a stronger immune response to pathogens than men. [34] However, the idea that men have weaker immune systems due to the supposed immuno-suppressive actions of testosterone is unfounded. [35]
There is debate as to whether the pursuit of longevity is a worthwhile health care goal. Bioethicist Ezekiel Emanuel, who is also one of the architects of ObamaCare, has argued that the pursuit of longevity via the compression of morbidity explanation is a "fantasy" and that longevity past age 75 should not be considered an end in itself. [36] This has been challenged by neurosurgeon Miguel Faria, who states that life can be worthwhile in healthy old age, that the compression of morbidity is a real phenomenon, and that longevity should be pursued in association with quality of life. [37] Faria has discussed how longevity in association with leading healthy lifestyles can lead to the postponement of senescence as well as happiness and wisdom in old age. [38]
Most biological organisms have a naturally limited longevity due to aging, unlike a rare few that are considered biologically immortal.
Given that different species of animals and plants have different potentials for longevity, the disrepair accumulation theory of aging tries to explain how the potential for longevity of an organism is sometimes positively correlated to its structural complexity. It suggests that while biological complexity increases individual lifespan, it is counteracted in nature since the survivability of the overall species may be hindered when it results in a prolonged development process, which is an evolutionarily vulnerable state. [39]
According to the antagonistic pleiotropy hypothesis, one of the reasons biological immortality is so rare is that certain categories of gene expression that are beneficial in youth become deleterious at an older age.
Longevity myths are traditions about long-lived people (generally supercentenarians), either as individuals or groups of people, and practices that have been believed to confer longevity, but for which scientific evidence does not support the ages claimed or the reasons for the claims. [40] [41] A comparison and contrast of "longevity in antiquity" (such as the Sumerian King List, the genealogies of Genesis, and the Persian Shahnameh) with "longevity in historical times" (common-era cases through twentieth-century news reports) is elaborated in detail in Lucian Boia's 2004 book Forever Young: A Cultural History of Longevity from Antiquity to the Present and other sources. [42]
After the death of Juan Ponce de León, Gonzalo Fernández de Oviedo y Valdés wrote in Historia General y Natural de las Indias (1535) that Ponce de León was looking for the waters of Bimini to cure his aging. [43] Traditions that have been believed to confer greater human longevity also include alchemy, [44] such as that attributed to Nicolas Flamel. In the modern era, the Okinawa diet has some reputation of linkage to exceptionally high ages. [45]
Longevity claims may be subcategorized 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 ...." [46] The estimate of 17 years per decade was corroborated by the 1901 and 1911 British censuses. [46] Time magazine considered that, by the Soviet Union, longevity had been elevated to a state-supported "Methuselah cult". [47]
Robert Ripley regularly reported supercentenarian claims in Ripley's Believe It or Not! , usually citing his own reputation as a fact-checker to claim reliability. [48]
Longevity in other animals can shed light on the determinants of life expectancy in humans, especially when found in related mammals. However, important contributions to longevity research have been made by research in other species, ranging from yeast to flies to worms. In fact, some closely related species of vertebrates can have dramatically different life expectancies, demonstrating that relatively small genetic changes can have a dramatic impact on aging. For instance, Pacific Ocean rockfishes have widely varying lifespans. The species Sebastes minor lives a mere 11 years while its cousin Sebastes aleutianus can live for more than 2 centuries. [49] Similarly, a chameleon, Furcifer labordi , is the current record holder for shortest lifespan among tetrapods, with only 4–5 months to live. [50] By contrast, some of its relatives, such as Furcifer pardalis, have been found to live up to 6 years. [51]
There are studies about aging-related characteristics of and aging in long-lived animals like various turtles [52] [53] and plants like Ginkgo biloba trees. [54] They have identified potentially causal protective traits and suggest many of the species have "slow or [times of][ clarification needed ] negligible[ clarification needed ] senescence" (or aging). [55] [52] [53] The jellyfish T. dohrnii is biologically immortal and has been studied by comparative genomics. [56] [57]
Honey bees (Apis mellifera) are eusocial insects that display dramatic caste-specific differences in longevity. Queen bees live for an average of 1-2 years, compared to workers who live on average 15-38 days in summer and 150-200 days in winter. [58] Worker honey bees with high amounts of flight experience exhibit increased DNA damage in flight muscle, as measured by elevated 8-Oxo-2'-deoxyguanosine, compared to bees with less flight experience. [59] This increased DNA damage is likely due to an imbalance of pro- and anti-oxidants during flight-associated oxidative stress. Flight induced oxidative DNA damage appears to hasten senescence and reduce longevity in A. mellifera. [59]
Gene editing via CRISPR-Cas9 and other methods have significantly altered lifespans in animals. [67] [68] [69]
Human life expectancy is a statistical measure of the estimate of the average remaining years of life at a given age. The most commonly used measure is life expectancy at birth. This can be defined in two ways. Cohort LEB is the mean length of life of a birth cohort and can be computed only for cohorts born so long ago that all their members have died. Period LEB is the mean length of life of a hypothetical cohort assumed to be exposed, from birth through death, to the mortality rates observed at a given year. National LEB figures reported by national agencies and international organizations for human populations are estimates of period LEB.
Senescence or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle. However, the resulting effects of senescence can be delayed. The 1934 discovery that calorie restriction can extend lifespans by 50% in rats, the existence of species having negligible senescence, and the existence of potentially immortal organisms such as members of the genus Hydra have motivated research into delaying senescence and thus age-related diseases. Rare human mutations can cause accelerated aging diseases.
Life extension is the concept of extending the human lifespan, either modestly through improvements in medicine or dramatically by increasing the maximum lifespan beyond its generally-settled biological limit of around 125 years. Several researchers in the area, along with "life extensionists", "immortalists", or "longevists", postulate that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement will eventually enable humans to have indefinite lifespans through complete rejuvenation to a healthy youthful condition (agerasia). The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.
A centenarian is a person who has reached the age of 100 years. Because life expectancies worldwide are below 100, the term is invariably associated with longevity. The United Nations estimated that there were 316,600 living centenarians worldwide in 2012, and 573,000 in 2020, almost quadruple the 2000 estimate of 151,000.
Maximum life span 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.
A supercentenarian, sometimes hyphenated as super-centenarian, is a person who is 110 years or older. This age is achieved by about one in 1,000 centenarians. Supercentenarians typically live a life free of significant age-related diseases until shortly before the maximum human lifespan is reached.
Biogerontology is the sub-field of gerontology concerned with the biological aging process, its evolutionary origins, and potential means to intervene in the process. The term "biogerontology" was coined by S. Rattan, and came in regular use with the start of the journal Biogerontology in 2000. It involves interdisciplinary research on the causes, effects, and mechanisms of biological aging. Biogerontologist Leonard Hayflick has said that the natural average lifespan for a human is around 92 years and, if humans do not invent new approaches to treat aging, they will be stuck with this lifespan. James Vaupel has predicted that life expectancy in industrialized countries will reach 100 for children born after the year 2000. Many surveyed biogerontologists have predicted life expectancies of more than three centuries for people born after the year 2100. Other scientists, more controversially, suggest the possibility of unlimited lifespans for those currently living. For example, Aubrey de Grey offers the "tentative timeframe" that with adequate funding of research to develop interventions in aging such as strategies for engineered negligible senescence, "we have a 50/50 chance of developing technology within about 25 to 30 years from now that will, under reasonable assumptions about the rate of subsequent improvements in that technology, allow us to stop people from dying of aging at any age". The idea of this approach is to use presently available technology to extend lifespans of currently living humans long enough for future technological progress to resolve any remaining aging-related issues. This concept has been referred to as longevity escape velocity.
The Hayflick limit, or Hayflick phenomenon, is the number of times a normal somatic, differentiated human cell population will divide before cell division stops.
Biodemography is a multidisciplinary approach, integrating biological knowledge with demographic research on human longevity and survival. Biodemographic studies are important for understanding the driving forces of the current longevity revolution, forecasting the future of human longevity, and identification of new strategies for further increase in healthy and productive life span.
The Gompertz–Makeham law states that the human death rate is the sum of an age-dependent component, which increases exponentially with age and an age-independent component. In a protected environment where external causes of death are rare, the age-independent mortality component is often negligible. In this case the formula simplifies to a Gompertz law of mortality. In 1825, Benjamin Gompertz proposed an exponential increase in death rates with age.
Enquiry into the evolution of ageing, or aging, aims to explain why a detrimental process such as ageing would evolve, and why there is so much variability in the lifespans of organisms. The classical theories of evolution suggest that environmental factors, such as predation, accidents, disease, and/or starvation, ensure that most organisms living in natural settings will not live until old age, and so there will be very little pressure to conserve genetic changes that increase longevity. Natural selection will instead strongly favor genes which ensure early maturation and rapid reproduction, and the selection for genetic traits which promote molecular and cellular self-maintenance will decline with age for most organisms.
Poly [ADP-ribose] polymerase 1 (PARP-1) also known as NAD+ ADP-ribosyltransferase 1 or poly[ADP-ribose] synthase 1 is an enzyme that in humans is encoded by the PARP1 gene. It is the most abundant of the PARP family of enzymes, accounting for 90% of the NAD+ used by the family. PARP1 is mostly present in cell nucleus, but cytosolic fraction of this protein was also reported.
Ageing is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In a broader sense, ageing can refer to single cells within an organism which have ceased dividing, or to the population of a species.
A centenarian is a person who has attained the age of 100 years or more. Research on centenarians has become more common with clinical and general population studies now having been conducted in France, Hungary, Japan, Italy, Finland, Denmark, the United States, and China. Centenarians are the second fastest-growing demographic in much of the developed world. By 2030, it is expected that there will be around a million centenarians worldwide. In the United States, a 2010 Census Bureau report found that more than 80 percent of centenarians are women.
Negligible senescence is a term coined by biogerontologist Caleb Finch to denote organisms that do not exhibit evidence of biological aging (senescence), such as measurable reductions in their reproductive capability, measurable functional decline, or rising death rates with age. There are many species where scientists have seen no increase in mortality after maturity. This may mean that the lifespan of the organism is so long that researchers' subjects have not yet lived up to the time when a measure of the species' longevity can be made. Turtles, for example, were once thought to lack senescence, but more extensive observations have found evidence of decreasing fitness with age.
The anti-aging movement is a social movement devoted to eliminating or reversing aging, or reducing the effects of it. A substantial portion of the attention of the movement is on the possibilities for life extension, but there is also interest in techniques such as cosmetic surgery which ameliorate the effects of aging rather than delay or defeat it.
Biomarkers of aging are biomarkers that could predict functional capacity at some later age better than chronological age. Stated another way, biomarkers of aging would give the true "biological age", which may be different from the chronological age.
Genetics of aging is generally concerned with life extension associated with genetic alterations, rather than with accelerated aging diseases leading to reduction in lifespan.
In biogerontology, the disposable soma theory of aging states that organisms age due to an evolutionary trade-off between growth, reproduction, and DNA repair maintenance. Formulated by British biologist Thomas Kirkwood, the disposable soma theory explains that an organism only has a limited amount of resources that it can allocate to its various cellular processes. Therefore, a greater investment in growth and reproduction would result in reduced investment in DNA repair maintenance, leading to increased cellular damage, shortened telomeres, accumulation of mutations, compromised stem cells, and ultimately, senescence. Although many models, both animal and human, have appeared to support this theory, parts of it are still controversial. Specifically, while the evolutionary trade-off between growth and aging has been well established, the relationship between reproduction and aging is still without scientific consensus, and the cellular mechanisms largely undiscovered.
This timeline lists notable events in the history of research into senescence or biological aging, including the research and development of life extension methods, brain aging delay methods and rejuvenation.
Chuan xiong ... has long been a key herb in the longevity tradition of China, prized for its powers to boost the immune system, activate blood circulation, and relieve pain.
Taoist devotion to immortality is important to us for two reasons. The techniques may be of considerable value to our goal of a healthy old age, if we can understand and adapt them. Secondly, the Taoist longevity tradition has brought us many interesting remedies.
The Old Man of the Sea / Yaupa / a native of Futuna, one of the New Hebrides Islands / regularly worked his own farm at the age of 130 / He died in 1899 of measles — a children's disease ... Horoz Ali, the last Turkish gatekeeper of Nicosia, Cyprus, lived to the age of 120 ... Francisco Huppazoli (1587–1702) of Casale, Italy, lived 114 years without a day's illness and had 4 children by his 5th wife — whom he married at the age of 98
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