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Demography of Aging

Age Composition of Societies

Demography is the study of changes in the size, diversity, distribution, and composition of human populations over time.

Demography is the study of the structure and composition of human populations. Demographers use statistical data to analyze and describe changes in the size, diversity, distribution, and composition of human populations over time. This analysis might concern the age composition of a population, the incidence of problems such as poverty and disease, and the distribution of wealth.

Age composition refers to the proportions of people within different age categories in a given society. A greater or lesser proportion of older people has major implications for the sustainability of those social welfare programs on which the elderly rely. For example, older people have a greater need for health care and welfare assistance. Knowledge of the age composition of a society also helps governments and other institutions plan spending on infrastructure and other projects. Demographers also consider other data alongside age, such as wealth, income, and health. Combining data in this way helps identify trends such as differing wealth distribution and health outcomes across generations.

A common way of organizing demographic data is to organize it into age cohorts, or groups of people categorized according to age, sometimes referred to as generations. A prominent example of one of these age cohorts is the baby boom generation. Baby boomers are members of the generation born between 1944 and 1961. These years witnessed a huge increase in the birth rate resulting from prosperity following World War II. About 65 million Americans were born in this period. Early in the 21st century, the baby boom generation began reaching old age. This large proportion of elderly people in American society has posed many challenges for policy makers.

Changes in Global Age Composition

Demographers suggest that the world's age composition has changed and will continue to change as each generation lives longer than the generation before.
Around the world, people are living longer. This is especially true in industrialized nations such as the United States, United Kingdom, Italy, and Japan. Since the late 19th century, life expectancy, or the average life span among a population, has increased in each of these countries. This trend is owed to improvements in medical science, increased access to health care, improved nutrition (resulting from an increase in societal wealth and advances in agricultural science), and a reduction in child mortality. As life expectancy increases, however, a number of other demographic effects are felt. As more people live into old age, the proportion of elders increases. Sociologists say that these populations are aging, or "graying," in reference to the tendency for hair to become gray in old age.

Percentage of Population Age 65 Years or Older (2015)

Sociologists study demographic transition, the processes that impact the age structure of countries and regions. Multiple factors, including public health systems, infrastructure, and birth rates, influence population aging.
An aging population is partly a result of the increased productivity of industrialized societies. Industrialization increased life expectancy, as advances in technology made agriculture more productive, leading to a more stable food supply. Industrialization also helped to raise standards of living, giving more people access to higher quality shelter and better sanitary conditions. Advances in medicine and declining birth rates also contribute to aging populations. As people live longer and women have fewer babies, on average, the percentage of older people in a population increases.

The aging of the population is an issue facing many countries. This trend is likely to continue throughout the 21st century in the wake of continued industrial development and advances in medicine and technology. For example, the U.S. Census Bureau projects that by 2030 the U.S. population will include more older people than children for the first time in the country's history.

Societies with aging populations face several challenges. As a rule, elderly people require more health care and other support than younger people. As elderly people leave the workforce, their care is partly paid for by the labor of younger people. Improved life expectancy means that people in aging societies are living a greater part of their lives in retirement than was the case when social welfare programs, such as Social Security and Medicare, were instituted. As a result, those programs face an acute pressure on their funding. The United States faces major decisions about how to care for the baby boom generation, who began reaching their 60s in 2004.

However, it is possible that the trend of aging populations will be reversed in the future. Changing social attitudes, war, resource scarcity, and climate change could all end the global trend toward longer lives and older populations. Immigration patterns can also change the demographic makeup of societies. Migrants tend to be relatively young. This means that increased migration to countries with aging populations can increase the younger proportion of the population, thus increasing the number of people available to care for elders and to pay into social security systems that elders rely upon.