Centenarian

A centenarian is a person who lives to or beyond the age of 100 years. Because average global life expectancies are less than 100, the term is invariably associated with longevity. A supercentenarian is a person who has lived to the age of 110 or more, something only achieved by about one in 1,000 centenarians. Even rarer is a person who has lived to age 115 â€" there are only 34 people in recorded history who have indisputably reached this age, of whom only Misao Okawa, Gertrude Weaver, Jeralean Talley, Susannah Mushatt Jones, and Bernice Madigan are still living. In 2012, the United Nations estimated that there were 316,600 living centenarians worldwide. As life expectancy is increasing across the world, the population of centenarians is expected to raise significantly in the future. According to ONS, one third of babies born in 2013 in the UK are expected to live to 100.

Current incidence

The United States currently has the greatest number of known centenarians of any nation with 53,364 according to the 2010 Census, or 17.3 per 100,000 people. In 2010, 82.8% of US centenarians were female. Japan has the second-largest number of centenarians, with an estimated 51,376 as of September 2012, and the highest proportion of centenarians at 34.85 per 100,000 people. Japan started recording its centenarians in 1963, at which time the number of Japanese centenarians was found to be 153. This number surpassed the 10,000 mark in 1998, 20,000 in 2003, and 40,000 in 2009. 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.

Centenarian populations by country

The total number of 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 and 455,000 in 2009. 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 tabulated lists estimated centenarian populations by country, including both the latest and the earliest known estimates, where available.

Traditions

In many countries, people receive a gift or congratulations on their 100th birthday. In the United Kingdom and the other Commonwealth realms, the Queen sends greetings (formerly as a telegram) on the 100th birthday and on every birthday starting with the 105th. The tradition was first practiced in 1908, when the Secretary for King Edward VII sent a congratulatory letter to Reverend Thomas Lord of Horncastle, 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 formalized from 1917, under the reign of King George V.

In the United States, centenarians traditionally receive a letter from the President, congratulating them for their longevity. NBC's Today Show show has also named new centenarians on air since 1983. Centenarians born in Ireland receive a €2,540 "Centenarians' Bounty" and a letter from the President of Ireland, even if they are resident abroad. Japanese centenarians receive a silver cup and a certificate from the Prime Minister of Japan upon their 100th birthday, honouring them for their longevity and prosperity in their lives. Swedish centenarians receive a telegram from the King and Queen of Sweden. Centenarians born in Italy receive a letter from the President of Italy. In Japan, a "National Respect for the Aged Day" has been celebrated every September since 1966.

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, the term 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 celebrationsâ€"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".

Centenarians in ancient times

While the density of centenarians per capita was much lower in ancient times than today, the data suggest that they were not unheard of. However, ancient demographics are biased in favor of wealthy or powerful individuals rather than the ordinary person. Grmek and Gourevitch speculate that during the Classical Greek period, anyone who lived past the age of five years â€" surviving all the common childhood illnesses of that era â€" had a reasonable chance of living to a relatively old age. The average life expectancy in 400 BC was estimated to be around 30 years. One demographer of ancient civilizations reported that Greek men lived to 45 years (based on a sample size of 91), while women lived to 36.2 years (based on a sample size of 55). Notably, the gender statistics are inverted compared to today â€" childbirth at the time had a far higher mortality rate than in modern times, skewing female statistics downward. It was common for average citizens to take great care in their hygiene, Mediterranean diet and exercise, although there was much more male trauma per capita than today, due to military service being virtually universal for citizens of Ancient Greece. This also biased the statistics for men downward.

Diogenes Laertius (c. 250 AD) gives one of the earliest references regarding the plausible centenarian longevity given by a scientist, the astronomer Hipparchus of Nicea (c. 185 â€" c. 120 BC), who, according to the doxographer, assured that the philosopher Democritus of Abdera (c. 470/460 â€" c. 370/360 BC) lived 109 years. All other accounts about Democritus given by the ancients appear to agree on the fact that the philosopher lived at least 90 years. However, such longevity would not be dramatically out of line with that of other ancient Greek philosophers thought to have lived beyond the age of 90 (e.g.: Xenophanes of Colophon, c. 570/565 â€" c. 475/470 BC; Pyrrho of Ellis, c. 360 V c. 270 BC; Eratosthenes of Cirene c. 285 â€" c. 190 BC, etc.). The case of Democritus differs from the case of, for example, Epimenides of Crete (7th, 6th centuries BC), who is said to have lived an implausible 154, 157 or 290 years, depending on the source.

Numerous other historical figures were reputed to have lived past 100. The sixth dynasty Egyptian ruler Pepi II is believed by some Egyptologists to have lived to the age of 100 or more (c. 2278 BC â€" c. 2184 BC), as he ruled for 94 years. However, this is disputed, as others claim the length of his reign was actually 64 years. Hosius of Córdoba, the man who convinced Constantine the Great to call the First Council of Nicaea, reportedly lived to age 102. The Chronicon of Bernold of Constance records the death in 1097 of Azzo marchio de Longobardia, pater Welfonis ducis de Baiowaria, commenting that he was iam maior centenario. Ultimately, there is no reason to believe that centenarians did not exist in antiquity, even if they were not commonplace.

Research into centenarians

Research carried out in the Italy suggests that the healthy centenarians have high levels of both vitamin A and vitamin E and that this seems to be important in guaranteeing their extreme longevity. Other research contradicts this, however, and has found that these findings do 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 and higher, 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 having parents who 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.

According John W. Santrock's book A Topical Approach to Life-Span Development, there are five factors that research has suggested are most important to longevity in centenarians:

1. heredity and family history
2. health, i.e. weight, diet, whether or not a person smokes, amount of exercise
3. education level
4. personality
5. lifestyle

Santrock's book also noted that the largest group of centenarians are women who have never been married. Also, people who have been through traumatic life events learn to cope better with stress and poverty and are more likely to reach centenarian status.

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:

1. A diet that is heavy on grains, fish, and vegetables and light on meat, eggs, and dairy products.
2. Low-stress lifestyles, which are proven significantly less stressful than that of the mainland inhabitants of Japan.
3. A caring community, where older adults are not isolated and are taken better care of.
4. High levels of activity, where locals work until an older age than the average age in other countries, and more emphasis on activities like walking and gardening to keep active.
5. Spirituality, where a sense of purpose comes from involvement in spiritual matters and prayer eases the mind of stress and problems.

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 the 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, 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 its bed, resulting in a police investigation into centenarians listed over the age of 105. Soon after the discovery, the Japanese police found that at least 200 other Japanese centenarians were missing, and began a nationwide search in early August 2010. This incident led to growing concerns that Japan's welfare system can be exploited by unscrupulous family members keen to continue receiving benefits after the pensioners die. In one case, the remains of a mother thought to be 104 had been stuffed into her son's backpack for nearly a decade; in another, a man received around 9.5 million yen in pension payments despite his wife having died six years previously.

Additional research

Centenarians are often the subject of news stories that focus on the fact that they are over 100 years old. Other than 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:

• 105-Year-Old Texas Woman Reveals Bacon as her Secret behind Long Life

• 107-year-old Arkansas man dies in shootout with S.W.A.T.

• Seattle forces 103-year-old to sell parking lot so city can turn it into â€" a parking lot

• 102-year-old man sells rare coin collection for $23M at NYC auction