Centenarian
A centenarian is a person who has reached the age of 100 years. Because life expectancies worldwide are below 100 years, the term is invariably associated with longevity. In 2012, the United Nations estimated that there were 316,600 living centenarians worldwide. As world population and life expectancy continue to increase, the number of centenarians is expected to increase substantially in the 21st century. According to the UK ONS, one-third of babies born in 2013 in the UK are expected to live to 100. Supercentenarian. A supercentenarian, sometimes hyphenated as super-centenarian, is a person who has reached the  age of 110 years, something only achieved by about one in 1000 centenarians. Even rarer is a person who has lived to age 115 – there are fewer than 100 people in recorded history who have indisputably reached this age. , Lucile Randon, Tekla Juniewicz, Maria Branyas Morera, and Casilda Benegas are the only living people with such an age. Current incidences. The United Nations predicts that there are 573,000 centenarians currently, almost quadruple the 151,000 suggested in the year 2000. According to a 1998 United Nations demographic survey, Japan is expected to have 272,000 centenarians by 2050; other sources suggest that  the number could be closer to 1 million. The incidence of centenarians in Japan was one per 3,522 people in 2008. In Japan, the number of centenarians is highly skewed towards females. Japan in fiscal year 2016 had 57,525 female centenarians, while there were 8,167 males, a ratio of 7:1. The increase of centenarians was even more skewed at 11.6:1. Centenarian populations by country. The total number of living centenarians in the world remains uncertain. It was estimated by the Population Division of the United Nations as 23,000 in 1950, 110,000 in 1990, 150,000 in 1995, 209,000 in 2000, 324,000  in 2005, 455,000 in 2009 and 573,000 in 2021. However, these older estimates did not take into account the contemporary downward adjustments of national estimates made by several countries such as the United States; thus, in 2012, the UN estimated there to be only 316,600 centenarians worldwide. The following table gives estimated centenarian populations by country, including both the latest and the earliest known estimates, where available. Recognition and congratulations worldwide. In many countries, people receive a gift or congratulations from federal/state institutions on their 100th birthday. Europe. Centenarians born in Ireland receive a €2,540 "Centenarians' Bounty" and  a letter from the President of Ireland, even if they are resident abroad. In the Netherlands, the King and the King's Commissioner sends a letter on the 100th birthday and on every birthday beginning with the 105th. German centenarians receive a letter of congratulations from the President of Germany. Centenarians born in Italy receive a letter of congratulations from the President of Italy. Swedish centenarians receive a telegram from the King and Queen of Sweden. United Kingdom and Commonwealth. In the United Kingdom and the other Commonwealth realms, the monarch sends greetings (formerly as a telegram) on the 100th  birthday and on every birthday beginning with the 105th. The centenarian acrobat Henry Johnson received a congratulatory letter from Edward VII via Viscount Knollys in 1906. The tradition of Royal congratulations continued in 1908, when the Secretary for King Edward VII sent a congratulatory letter to Reverend Thomas Lord of Horncastle in a newspaper clipping, declaring, "I am commanded by the King to congratulate you on the attainment of your hundredth year, after a most useful life". The practice was formalised from 1917, under the reign of King George V, who also sent congratulations on the attainment of a Diamond  Wedding Anniversary (or jubilee) marking 60 years of marriage. Queen Elizabeth II sends a greeting card style with the notation: "I am so pleased to know that you are celebrating your one-hundredth birthday, I send my congratulations and best wishes to you on such a special occasion", thereafter each few years the card is updated with a current picture of the Queen to ensure people do not receive the same card more than once. The Queen further sends her congratulations on one's 105th birthday and every year thereafter as well as on special wedding anniversaries; people must apply  for greetings three weeks before the event, on the official British Monarch's website. Russian Federation. In 2019, there were reported to be over 20,000 centenarians living in Russia, a sharp increase from 6,700 in 2007. Centenarians in Russia receive a letter from Vladimir Putin, officially congratulating them for reaching one hundred years. North America. In the United States, centenarians traditionally receive a letter from the President, congratulating them for their longevity. Asia. Japanese centenarians receive a silver cup and a certificate from the Prime Minister of Japan upon the Respect for the Aged Day following their 100th birthday, honouring  them for their longevity and prosperity in their lives. In Madhya Pradesh, the award known as Shatayu Samman is given out to persons who live at least 100 years to promote awareness of good health. Worldwide cultural traditions and rituals. An aspect of blessing in many cultures is to offer a wish that the recipient lives to 100 years old. Among Hindus, people who touch the feet of elders are often blessed with "May you live a hundred years". In Sweden, the traditional birthday song states, "May he/she live for one hundred years". In Judaism, "May you live to  be 120 years old" is a common blessing. In Poland, "Sto lat", a wish to live a hundred years, is a traditional form of praise and good wishes, and the song "sto lat, sto lat" is sung on the occasion of the birthday celebrations—arguably, it is the most popular song in Poland and among Poles around the globe. Chinese emperors were hailed to live ten thousand years, while empresses were hailed to live a thousand years. In Italy, "A hundred of these days!" ("cento di questi giorni") is an augury for birthdays, to live to celebrate 100 more birthdays . Some Italians say "Cent'anni!", which means "a hundred years", in that they wish that they could all live happily for a hundred years. In Greece, wishing someone Happy Birthday ends with the expression "να τα εκατοστήσεις" ("na ta ekatostisis"), which can be loosely translated as "may you make it one hundred birthdays". In Sri Lanka, it is a custom to bless as "you may live 220 instead of 120". Centenarians in antiquity. While the number of centenarians per capita was much lower in ancient times than today, the data suggest that they were not unheard of. Estimates of life expectancy  in antiquity are far lower than modern values mostly due to the far greater incidence of deaths in infancy or childhood. Those who lived past early childhood had a reasonable chance of living to a relatively old age. The assumption of what constitutes "old age", or being "elderly", at least, seems to have remained unchanged since antiquity, the line being generally drawn at either sixty or sixty-five years; Psalm 90:10 in the Hebrew Bible appears to give seventy to eighty years as the natural life expectancy of a person surviving into old age, "The years of our life are  seventy, or even by reason of strength eighty". A survey of the lifespans of male individuals with entries in the "Oxford Classical Dictionary" (i.e., a sample pre-selected to include those who lived long enough to attain historical notability) found a median lifespan of 72 years, and a range of 32 to 107 years, for 128 individuals born before 100 BC (though the same study found a median lifespan of 66 years for 100 individuals born after 100 BC but no later than 602 AD); by comparison, male individuals listed in "Chambers Biographical Dictionary" who died between 1900 and 1949  had a median lifespan of 71.5 years, with a range between 29 and 105 years. The author of the 1994 study concluded that it was only in the second half of the 20th century that medical advances have extended the life expectancy of those who live into adulthood. Reliable references to individuals in antiquity who lived past 100 years are quite rare, but they do exist. For instance, Cicero's wife Terentia was reported by Pliny the Elder to have lived from 98 BC to 6 AD, 104 years. Regnal dates of Bronze Age monarchs are notoriously unreliable; the sixth  dynasty Egyptian ruler Pepi II is sometimes listed as having lived c. 2278 – c. 2184 BC, as he is said to have reigned for 94 years, but alternative readings cite a reign of just 64 years. Adad-guppi, mother of the last king of the Neo-Babylonian Empire Nabonidus apparently lived from c. 648-544 BC (c. 104 years) according to inscriptions on funeral steles. Diogenes Laërtius (c. AD 250) gives one of the earliest references regarding the plausible centenarian longevity given by a scientist, the astronomer Hipparchus of Nicaea (c. 185 – c. 120 BC), who, according to the doxographer , assured that the philosopher Democritus of Abdera (c. 470/460 – c. 370/360 BC) lived 109 years. All other ancient accounts of Democritus appear to agree that the philosopher lived at least 90 years. The case of Democritus differs from those of, for example, Epimenides of Crete (7th and 6th centuries BC), who is said to have lived an implausible 154, 157, or 290 years, depending on the source. Other ancient Greek philosophers thought to have lived beyond the age of 90 include Xenophanes of Colophon (c. 570/565 – c. 475/470 BC), Pyrrho of Ellis (c. 360 – c. 270 BC), and Eratosthenes of  Cirene (c. 285 – c. 190 BC). Hosius of Córdoba, the man who convinced Constantine the Great to call the First Council of Nicaea, reportedly lived to age 102. A rare record of an ordinary person who lived to be a centenarian is the tombstone of Roman British legionary veteran Julius Valens, inscribed "VIXIT ANNIS C". In the medieval period, Albert Azzo II, Margrave of Milan (d. 1097) is reported by Bernold of Constance as having lived past 100 years ("iam maior centenario"). Research. Research in Italy suggests that healthy centenarians have high levels of both vitamin A and vitamin E  and that this seems to be important in causing their extreme longevity. Other research contradicts this, however, and has found that this theory does not apply to centenarians from Sardinia, for whom other factors probably play a more important role. A preliminary study carried out in Poland showed that, in comparison with young healthy female adults, centenarians living in Upper Silesia had significantly higher red blood cell glutathione reductase and catalase activities, although serum levels of vitamin E were not significantly higher. Researchers in Denmark have also found that centenarians exhibit a high activity of glutathione reductase in red blood  cells. In this study, the centenarians having the best cognitive and physical functional capacity tended to have the highest activity of this enzyme. Other research has found that people whose parents became centenarians have an increased number of naïve B cells. It is well known that the children of parents who have a long life are also likely to reach a healthy age, but it is not known why, although the inherited genes are probably important. A variation in the gene FOXO3A is known to have a positive effect on the life expectancy of humans, and is found much more  often in people living to 100 and beyond – moreover, this appears to be true worldwide. Men and women who are 100 or older tend to have extroverted personalities, according to Thomas T. Perls, the director of the New England Centenarian Study at Boston University. Centenarians will often have many friends, strong ties to relatives and high self-esteem. In addition, some research suggests that the offspring of centenarians are more likely to age in better cardiovascular health than their peers. DNA repair. 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 years old) individuals. The lymphocytic cells of centenarians have characteristics typical of cells from young people, both in their capability of priming the mechanism of repair after HO sublethal oxidative DNA damage and in their PARP capacity. PARP activity measured in the permeabilized mononuclear leukocyte blood cells of thirteen mammalian species correlated with maximum lifespan of the species. These findings suggest that PARP mediated DNA repair activity contributes to the longevity of centenarians, consistent with the DNA damage theory of aging. Japanese bio-study. Many experts attribute  Japan's high life expectancy to the typical Japanese diet, which is particularly low in refined simple carbohydrates, and to hygienic practices. The number of centenarians in relation to the total population was, in September 2010, 114% higher in Shimane Prefecture than the national average. This ratio was also 92% higher in Okinawa Prefecture. In Okinawa, studies have shown five factors that have contributed to the large number of centenarians in that region: Although these factors vary from those mentioned in the previous study, the culture of Okinawa has proven these factors to be important in its large population of  centenarians. A historical study from Korea found that male eunuchs in the royal court had a centenarian rate of over 3%, and that eunuchs lived on average 14 to 19 years longer than uncastrated men. Centenarian controversy in Japan. The number of Japanese centenarians was called into question in 2010, following a series of reports showing that hundreds of thousands of elderly people had gone "missing" in the country. The deaths of many centenarians had not been reported, casting doubt on the country's reputation for having a large population of centenarians. In July 2010, Sogen Kato, a centenarian listed  as the oldest living male in Tokyo, registered to be aged 111, was found to have died some 30 years before; his body was found mummified in his bed, resulting in a police investigation into centenarians listed over the age of 105. Soon after the discovery, the Japanese Justice Ministry found that at least 234,354 other Japanese centenarians were "missing" and began a nationwide search in early August 2010. Epigenetic studies. By measuring the biological age of various tissues from centenarians, researchers may be able to identify tissues that are protected from aging effects. According to a study of 30  different body parts from centenarians and younger controls, the cerebellum is the youngest brain region (and probably body part) in centenarians (about 15 years younger than expected) according to an epigenetic biomarker of tissue age known as epigenetic clock. These findings could explain why the cerebellum exhibits fewer neuropathological hallmarks of age related dementias compared to other brain regions. Further, the offspring of semi-supercentenarians (subjects who reached an age of 105–109 years) have a lower epigenetic age than age-matched controls (age difference=5.1 years in peripheral blood mononuclear cells) and centenarians are younger (8.6 years) than expected based on  their chronological age. Media references. Centenarians are often the subject of news stories, which often focus on the fact that they are over 100 years old. Along with the typical birthday celebrations, these reports provide researchers and cultural historians with evidence as to how the rest of society views this elderly population. Some examples: