By Joseph Chamie
By improving quality of life, advances in technology and medicine, and decreasing mortality among older adults, the 21st century is witnessing an increase in the number of centenarians.
It is estimated that in the world there are about half a million people who are over 100 years old, almost three times the number at the beginning of the century, despite the fact that the world population increased 20 percent.
While the world population is forecast to increase 80 percent by the end of this century, the number of centenarians is estimated to multiply by 60, reaching more than 26 million by 2100 (Figure 1.).
Source: Population Division of the United Nations.
People over 100 years old represent a small proportion of the 7,300 million inhabitants of the planet, about six per 100,000 inhabitants or one in 16,000.
But the proportion is projected to grow rapidly in the coming decades, and according to projections, by the end of this century there will be 236 people over the age of 100 per 100,000 or one in 425.
Currently, the countries with the highest number of centenarians are the United States (72,000), Japan (61,000), China (48,000), India (27,000) and Italy (25,000), which account for around half of the inhabitants of more 100 years.
By mid-century, those countries will continue to rank in the top five, but with larger numbers: China (882,000), Japan (441,000), the United States (378,000), Italy (216,000), and India (207,000).
Regarding the number of people over 100 years old per 100,000 inhabitants, the top five countries are Japan (48), Italy (41), Uruguay (34), Chile and France (31).
With 22 centenarians per 100,000 inhabitants, the United States is in 15th place, behind many European countries such as France, Germany, Spain and Great Britain.
By the middle of this century, Japan and Italy are forecast to have the highest proportion of centenarians with a higher number, roughly 400 per 100,000 inhabitants or one in 250.
The large proportion of long-lived people in some countries is largely due to their low mortality and age structures with many older adults.
Japan and Italy, for example, have the longest life expectancy in the world (83 years), the highest proportion of middle-aged adults (46 years) and large sectors over 65 (26 and 22 percent, respectively).
In terms of longevity, women have a clear advantage.
In general, the female population tends to live longer than men, with a disproportionately higher number of women in the older ages. They constitute 80 percent of the centenarians; and 96 percent of the 46 documented as supercentenarians, over 110 years old.
Therefore, it should not be surprising that the documented person who lived the longest is a woman. French Jeanne Calment was born in 1875 and died in 1997, having lived 122 years and 164 days. The man to have lived the longest was the Japanese Jiroemon Kimura, who died at 116 years and 54 days.
Calment and Kimura became people who lived at least a million hours or 114 years and 57 days. The odds of a centenarian reaching that milestone are very low, less than one in 1,000.
Some 30 documented people lived more than 114 years.
Until recently, the oldest living person was Misao Okawa from Japan, who lived 117 years and 26 days.
Today, the oldest living person is Susannah Mushatt Jones, in the United States, who was born on July 6, 1899. She is closely followed by Emma Morano, in Italy, who was born on November 29, 1899.
The oldest living man is the supercentennial Yasutaro Koide of Japan, who was born on March 13, 1903.
Studying centenarians is beneficial, as it provides a better understanding of the aging process. Research helps identify ways to increase life expectancy and improve quality of life for older people who continue to age.
Among the key drivers of exceptional longevity are inherited "super" genes. Most of those who reach age 100 have a grandparent, father (mother), or brother (sister) who lived 90 years or more.
Some studies also show that siblings of centenarians have a significantly greater chance (17 times more for men and nine times more for women) of turning 100 than others born at the same time.
In addition to the importance of genetics, especially in older ages, some of the most notable factors related to longevity are: (a) good health and personal habits, such as diet, exercise, normal weight, low stress and do not smoke or abuse substances; (b) education and high knowledge; (c) a strong and committed social support system; (d) an optimistic outlook and positive emotions capable of adapting to change and planning alternatives.
Many centenarians say that they do not feel their chronological age, but think and feel many years younger.
The odds that a person will live to 100 years today are low, but they are certainly higher than those of their parents or grandparents.
A study in Britain calculated that the odds of a British newborn living to 100 years were one in four for a boy and one in three for a girl.
Other studies are more optimistic about the chances of being a centenarian, with estimates indicating that more than half of babies in the most industrialized nations have a life expectancy of 100 years.
The greatest longevity of around 100 years is, by the way, a blessing that most people would like to achieve.
But the growing number and proportion of centenarians and older adults raise questions about programs and policies, such as retirement age, health care, pensions, economic investments, taxes, social services, maintenance of the health, rehabilitation, care and assisted living.
Not paying attention or delaying attention to the profound consequences of an aging population and greater longevity is not only a short-term vision, but it also makes the situation of individuals, families and communities more difficult, as well as increases the economic cost for governments.
Despite political leaders trying to do otherwise, the demographic realities of an aging population and increasing human longevity cannot be sincerely denied or with political ingenuity or avoided by law.
In the end, the demographic duck will pay off one way or another.