Population Aging

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There were 420 million people in the world age sixty-five and older as of the year 2000, according to United Nations estimates (United Nations, 1998). If they all lived together under one flag, they would represent the third largest nation in the world. As a fraction of the total world population, the older population accounts for 7 percent, but this percentage varies considerably from one part of the world to another. For example, in the year 2000 only 19 percent of the total population of the world was living in more developed nations, yet 41 percent of the world's population age sixty-five or older was there, accounting for 14 percent of the total population of these wealthier countries. Still, that left the other 59 percent of people in the world age sixty-five and older living in the developing countries, even though the older population represented only 5 percent of those populations.

Between the years 2000 and 2010 the average annual rate of growth of the population age sixty-five and older in the world is projected to be 2.0 percent, compared to 1.2 percent per year for the total population (United Nations, 1998). That decade, however, represents the lull before the storm because the huge batch of babies born after World War II will have moved into the older ages in the following decade, between 2010 and 2020. During that decade, the population age sixty-five and older in the world will increase by 3.0 percent per year, while the total world population is projected to grow by only 1.1 percent. Furthermore, ever since 1970 the older population has been growing more quickly in less developed countries than in the more developed countries, even though the percent of the population that is sixty-five and older is still lower in those parts of the world. In 1970 the older population was almost evenly divided between more and less developed nations, but by the year 2020 we can expect there to be more than twice as many older people in the less developed nations as in the more developed. China contributed disproportionately to that number due to its large population size. In 2000, there were an estimated 89 million older people in China (one in five of all people in the world age sixty-five and older), even though they represented only 7 percent of China's population.

World's oldest and youngest populations

Using the percentage of the population age sixty-five and older as the index to an older population, the older populations of the world at the beginning of the twenty-first century are the wealthier countries of the worldthose of North America and Europe, plus Japan. The list is led by Italy (18.2 percent in 2000), followed by Greece (17.2 percent), Sweden (17.2 percent), Belgium (17.1 percent), and Japan (17.0 percent) (National Center for Health Statistics). The United States is twenty-seventh on this list, with 12.7 percent of the population age sixty-five and older.

By contrast, the younger nations are located especially in the developing regions of Africa, western Asia, and southern Asia. Using the percent under age fifteen as the index of a youthful population, the youngest populations in the year 2000 were Uganda and Yemen (both with 49 percent), followed by Burkina Faso, Niger, Burundi, Angola, and the Democratic Republic of the Congo (all with 48 percent). The forty youngest countries (all with more than 40 percent of the population under age fifteen) are in sub-Saharan Africa and the Middle East. In these countries, the population age sixty-five and older averages about 34 percent of the total. The obverse of that is that in the forty oldest countries of the world, the population under age fifteen tends to average only about 1620 percent of the population.

Within the United States, the state of Florida exceeds all others in its percentage of the population that is sixty-five or older (18 percent in 2000), followed by West Virginia and Pennsylvania (both at 15.6 percent), Iowa (15.2 percent), and North Dakota (15.0 percent). At the other extreme, the youngest states are, in order, Alaska, Utah, Georgia, California, and Texas.

Age distribution of a population

As death rates drop and life expectancy increases, the older population increases partly because life expectancy goes up somewhat at the older age. However, the most important impact on aging is due to the fact that lower mortality increases the probability of surviving to old age. For example, in 1900 the life expectancy in the United States was lower than in almost every country in the world today. At birth a male could have expected to live an average of only 46.3 years, while the average was 48.3 for females. These life expectancies were about the same as England at the time, but lower than most Scandinavian nations. At this level of mortality, a male baby had only a 36 percent chance of surviving from birth to age sixty-five, and a female baby had a 41 percent chance of living that long. For those who reached 65, the pattern of mortality in 1900 produced a life expectancy at age 65 of 11.5 additional years for males, and 12.2 additional years for females. In that year only 4.1 percent of the U.S. population was age sixty-five and older, comparable to the countries of sub-Saharan Africa and the Middle East as of the year 2000.

Significant improvements in mortality occurred in the United States and other developed countries between 1900 and 1950, with female life expectancy in the United States increasing from 48.3 to 71.1 years. In concert with that, the percentage age sixty-five and older doubled to 8.2 in 1950. By the end of the twentieth century, life expectancy at birth for females in the United States had improved to 79.2 years30.9 years more than at the turn of this century. Along with this, the percentage age sixty-five and older increased to 12.7 of the total. The century of improvement in life expectancy more than doubled the proportion of female babies surviving from birth to age sixty-five and has been a major reason for the increase in the number of older persons in the United States.

It is now commonplace for people to reach old age; so much so that long life is virtually taken for granted in richer nations. Furthermore, on reaching age sixty-five, females in the United States at the end of the twentieth century could expect to live an additional 19.2 years on averagean improvement of 7.0 years more beyond age 65 than was true a hundred years earlier, in 1900 (Anderson). This translates into more than a doubling of the proportion of women age sixty-five who will still be alive at age eighty. In 1997 in the United States, for example, more than two-thirds (68 percent) of the women alive at age sixty-five will still be alive at age eighty. The situation is not quite so favorable for males, but it has been improving for them, too.

Although declining mortality will always lead to an increase in the number of older people, the percentage age sixty-five and older will increase noticeably only if fertility also declines, as it always has historically in the context of the demographic transition (from low life expectancy and high fertility to high life expectancy and low fertility). Stable population models (Coale and Demeny) can be used to illustrate the percentage of the population that would be age sixty-five and older if a population maintained different combinations of mortality and fertility over time. For example, a country whose life expectancy was only thirty years would have 3.9 percent of the population age sixty-five and older if the total fertility rate (TFR) were five children per woman, and it would drop to 2.8 percent if the TFR went up to six. On the other hand, at a TFR of four or below at this low life expectancy, the population would be depopulating (because of fewer births than the number of deaths) so the percentage age sixty-five and older would be temporarily high, and then everybody would die off.

Stable population models show us that as life expectancy increases from thirty years to sixty years in a population where fertility remains at five children per woman, the percent age sixty-five and older goes down slightly. This actually happened in Mexico. Mortality was declining in Mexico between 1950 and 1970, but fertility had not begun to decline and so the older population was declining as a percent of the total population. However, as mortality continues to decline, eventually it gets low enough that the percentage representing the older population begins to increase even if fertility does not change. At any given level of life expectancy, the lower the level of fertility, the higher is the percentage of the population that is sixty-five or older. The typical path followed by the percentage of the population that is older as a country passes through the demographic transition is that the percentage goes from about 23 in premodern societies to 20 percent or even higher as life expectancy reaches eighty years and as fertility drops below replacement level.

The impact of migration on the growth of the older population is more complex than the effect of either mortality or fertility. Younger people are more likely to migrate than the elderly, but there is no biological limitation to migration and so it is that, although in general migration tends to leave the older population behind, there are other times when older people move disproportionately to specific areas (such as Florida in the United States) in search of "amenity-rich communities with sunnier, warmer and recreationally more enjoyable environments" (Rogers, 1992, p. 3). Migration affects population aging most by what older people do not dothey do not migrate very much. Throughout the world, older people tend to age in place. As a consequence, the process of urbanization, which occurs in concert with the demographic transition, has left older people abandoned in the countryside by their children who migrate to the cities in search of work. In general, outmigration tends to increase the percentage of the population that is older in a region, whereas immigration has the opposite effect.

Racial/ethnic differences in population aging in the United States

The general patterns discussed above do not capture the variability that can exist within any given population. In the United States, for example, racial and ethnic groups tend to differ in their patterns of mortality, fertility, and migration, and therefore they differ with respect to population aging. For the year 2000, the percentage of those sixty-five and older in the United States was 12.7 percent overall, but U.S. Census Bureau data suggest that 14.8 percent of the non-Hispanic white population was sixty-five or older, compared to 8.4 percent for blacks, 7.7 percent for Asians and Pacific Islanders, 7.4 percent for American Indians, Eskimo, and Aleut, and 6.0 percent for Hispanics (U.S. Census Bureau, 2000). Recent immigrants, who tend to be young and who thus pull down the percentage of the population that is older, influence the low figure for both Hispanics and Asians, as does their higher fertility than the non-Hispanic white population. On the other hand, blacks and American Indians tend to have both higher fertility and higher mortality than non-Hispanic whites, thus lowering the percentage that is older compared to non-Hispanic whites. Overall in 2000, non-Hispanic whites comprised 83.5 percent of all persons in the United States who were sixty-five or older, followed by blacks (8.1 percent), Hispanics (5.6 percent), Asian and Pacific Islanders (2.4 percent), and American Indians, Eskimo, and Aleut (0.4 percent).

The demographics of the older population are expected to look quite different by mid-century. Census Bureau projections suggest that by 2050 more than one in five Americans (20.4 percent) will be sixty-five or older. The percentages are projected to be 24.7 percent for non-Hispanic whites, 18.7 percent for blacks, 16.4 percent for American Indian, Eskimo, and Aleut, 15.0 for Asians and Pacific Islanders, and 13.9 percent for Hispanics. In that year the older population will mirror the racial and ethnic diversity that could be seen in the shopping malls of many American cities in the year 2000, as the teenagers in the malls in 2000 grow into the older ages by 2050. This will amount to an older population that is 64.2 percent non-Hispanic white, 16.4 percent Hispanic, 12.2 percent black, 6.5 percent Asian and Pacific Islander, and 0.6 percent American Indian, Eskimo, Aleut.

What does the future holdis demography destiny?

There are two important global trends ahead in population aging. Most noteworthy and most widely discussed is the graying of Europe, East Asia, and, to a lesser extent, North America. As of the year 2000, many countries in Europe, along with Japan and South Korea, were on the verge of depopulation, as a consequence of birth rates that have been persistently below the replacement level, and life expectancy that keeps increasing, even (or perhaps, especially) at the older ages. There is a concern about the social and economic impact of an ever-growing proportion of the population that is retired from the labor force and facing potentially debilitating health conditions associated with aging. In essence, the question is, Who will keep the economy going and support these individuals in their old age? There are several solutions. The birth rate could increase, but there are few signs that this will happen. The death rate could go up, but there is little likelihood of that. Workers could stay in the labor force longer and thus delay the economic impact of aging, but in fact the age at retirement has been going down, rather than up, over the past few decades in most rich countries. The other solution, and probably the most likely one, is for the populations of these countries to be rejuvenated by migrants from othertypically less developedcountries. The United Nations has termed this "replacement migration" (United Nations, 2000).

Migration is already serving to prop up the numbers of younger people in several European counties (especially France, Germany, and the United Kingdom), but in eastern Europe, in particular, migration would have to increase substantially to prevent depopulation and rapid aging. Japan has traditionally closed its doors to international migration, but demography could be destiny in pushing Japan to decide to allow more immigrants, such as those from the Philippines, to enter the country and become permanent residents, rather than just allowing a small number of short-term guest workers, as has been the policy for a long time. The United States and Canada, of course, are already experiencing replacement migration and for this reason neither country is on the verge of depopulation, and both have relatively low percentages of the population in the older ages, at least compared to Europe and Japan.

The other important issue for the future is the aging of the older population itself. Health technology has made significant gains in allowing people to survive stroke, heart attacks, cancer, and to live more comfortably with a variety of chronic ailments that would have incapacitated a person only a few decades ago. Although we continue to think of age sixty-five as somehow the beginning of old age, medical technologycombined with improvements in lifestyle such as less smoking and more exercisehave pushed back the age at which the average person's health noticeably slows down the pace of living and leads into eventual dependency on a caregiver. It is likely that age eighty or even beyond is closer now in the twenty-first century to what age sixty-five was in the late nineteenth and early twentieth centuries in terms of becoming decrepit and dependentthe things about aging that most younger people fear the most. This suggests that the process of population aging will push us to rethink our view about when old age actually begins.

John R. Weeks

See also Longevity: Reproduction; Longevity: Selection; Longevity: Social Aspects; Migration, Geographic; Mobility and Distribution.


Anderson, R. N. "United States Life Tables, 1997." National Vital Statistics Reports 47 (1999): 28.

Coale, A., and Demeny, P. Regional Model Life Tables and Stable Populations. New York: Academic Press, 1983.

National Center for Health Statistics. Older Americans 2000: Key Indicators of Well-Being; Federal Interagency Forum on Aging Related Statistics. Washington, D.C.: Centers for Disease Control, National Center for Health Statistics, 2000.

Rogers, A. "Introduction." Elderly Migration and Population Redistribution: A Comparative Study. Edited by Andrei Rogers. London: Bellhaven Press, 1992.

United Nations. World Population Projections to 2150. New York: Population Division of the United Nations, 1998.

United Nations. Replacement Migration: Is it a Solution to Declining and Ageing Populations? New York: Population Division of the United Nations, 2000.

U.S. Census Bureau. Population Projections of the United States by Age, Sex, Race, Hispanic Origin, and Nativity: 1999 to 2100. Washington, D.C.: U.S. Census Bureau, 2000. Available on the World Wide Web at www.census.gov

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Population Aging

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Population Aging