Longevity

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.

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.

Life expectancy, as of 2010

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]

• Developed countries: 77–90 years (e.g. Canada: 81.29 years, 2010 est.)
• Developing countries: 32–80 years (e.g. Mozambique: 41.37 years, 2010 est.)

Population longevities are increasing as life expectancies around the world grow:[2][3]

• Australia: 80 years in 2002, 81.72 years in 2010
• France: 79.05 years in 2002, 81.09 years in 2010
• Germany: 77.78 years in 2002, 79.41 years in 2010
• Italy: 79.25 years in 2002, 80.33 years in 2010
• Japan: 81.56 years in 2002, 82.84 years in 2010
• Monaco: 79.12 years in 2002, 79.73 years in 2011
• Spain: 79.06 years in 2002, 81.07 years in 2010
• United Kingdom: 80 years in 2002, 81.73 years in 2010
• United States: 77.4 years in 2002, 78.24 years in 2010

Long-lived individuals

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]

• Eilif Philipsen (21 July 1682 – 20 June 1785, 102 years, 333 days): first person to reach the age of 100 (on 21 July 1782) and whose age could be validated.[7][8]
• Geert Adriaans Boomgaard (1788–1899, 110 years, 135 days): first person to reach the age of 110 (on September 21, 1898) and whose age could be validated.
• Margaret Ann Neve, (18 May 1792 – 4 April 1903, 110 years, 346 days) the first validated female supercentenarian (on 18 May 1902).
• Jeanne Calment (1875–1997, 122 years, 164 days): the oldest person in history whose age has been verified by modern documentation.[note 1] This defines the modern human life span, which is set by the oldest documented individual who ever lived.
• Sarah Knauss (1880–1999, 119 years, 97 days): the third oldest documented person in modern times and the oldest American.
• Jiroemon Kimura (1897–2013, 116 years, 54 days): the oldest man in history whose age has been verified by modern documentation.
• Kane Tanaka (1903–2022, 119 years, 107 days): the second oldest documented person in modern times and the oldest Japanese.

Major factors

Evidence-based studies indicate that longevity is based on two major factors: genetics and lifestyle.[10]

Genetics

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]

Lifestyle

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]

Caloric 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.