1.1: Why study Human Aging?

Personal and Professional Reasons

Why have you chosen to study human aging? Why have others done so? For some people the answer is based on personal reasons. Younger individuals may expect to live long enough to reach old age and may wonder what will happen to them as they get older. They also may want to learn about aging so that they can improve their chances of aging happily and with good health. Curiosity or interest in bolstering one’s well-being may be a prime reason older individuals study aging. Still other individuals may have family members, friends, colleagues, or acquaintances who are experiencing aging. Their interest may spring from curiosity about what is happening to those other people. Beyond being curious, individuals may want to be better able to interact with and care for older people.

On a professional level, some individuals study human aging because their careers involve working with or caring for older people. The careers of others may entail carrying out research on or educating people about human aging.

Whatever your reasons for studying human aging, you should be aware that people have many reasons for doing so and that those who are studying human aging are being joined by a growing number of people.

Population Trends

(The data in this section are updated annually by the US Census Bureau and other agencies. Refer to the latest data and updates for Chapter 1). They do not yet include the 2020 census data. US Census Bureau 2020 census information is at US Census Bureau Reports - 2020 and 2017 .

Why has the study of aging become so important during the last few decades? One main reason is the rapid increase in the number of elderly people. According to current projections, this will continue until about A.D. 2030, after which the number of elderly people will rise more slowly (Figure 1.1). The proportion of elderly persons in the total population is also rising and will probably continue to grow for several decades. For example, in 2000, 21.4 percent of the population was over age 54. This number should rise to about 29.7 percent by the year 2020, it will probably increase to about 32.6 percent by the year 2040, and grow to about 35.2 percent by 2060 (Table 1.1). These data and projections for 2021 and thereafter will change due to substantial changes in immigration since 2010 and effects from the Coronavirus COVID-19 pandemic that began in early 2020.

There will also be an increase in both the number and proportion of people of higher ages (Figure 1.1, Figure 1.2 Graph) and Figure 1.2 Web Sites). For example, consider all people over age 65. In 2000, they numbered 34.8 million, made up 12.7 percent of the total population, and represented 59.2 percent of the population over age 55. By the year 2020 the corresponding statistics will probably change to 56.1 million, 16.9 percent, and 56.7 percent, respectively. By the year 2040 these values should reach 80.8 million, 21.6 and 66.3 percent, respectively. In 2020, those over age 84 will likely comprise 2.0 percent of the total population and 12.0 percent of people over age 64. By the year 2040, those over age 84 may make up 3.9 percent of the total population and 17.9 percent of people over age 64.

Figure 1.2 Graph - Elders as Percentages of U.S. Population 1900-2060 - a (US Census Bureau 2020 census information is at US Census Bureau Reports - 2020 and 2017 . Copyright 2020: Augustine G. DiGiovanna, Ph.D., Salisbury University, Maryland. Used with permission. )

Four factors explain these population changes. One factor is the high birth rates before 1920 and between 1946 and 1964, followed by a decrease after 1964 (Figure 1.3). A second is the high number of births between 1946 and 1964 (Figure 1.4 ). A third factor is the decline in childhood death rates, especially during the first year of life (Figure 1.5).

Figure 1.5 U.S. death rates for different age group 1900-2020 (Copyright 2020: Augustine G. DiGiovanna, Ph.D., Salisbury University, Maryland. Used with permission. )

Since the childhood death rate in 1940 was already low compared with 1900 and since the childhood death rate dropped substantially between 1940 and 1955, a much higher percentage of those born during these latter years survived into adulthood. The last factor is the increase in life expectancy at all ages, including middle age and old age. (Figure 1.6). Between 1900 and 1940, life expectancy for those over age 64 increased by less than one year, while it increased almost two years between 1940 and 1954. Life expectancy for those over age 64 increased more than 2.6 years since then. Because of these circumstances, a large group is now entering old age while a smaller group is replacing them as the younger segment of the population. This large group has become known as the "baby boomers" (Figure 1.7). Life expectancy for all adults including those over age 64 is expected to continue increasing for decades. Therefore, a larger percentage of those reaching old age will remain alive longer. In terms of populations and elders, the "baby boomer bump" is the wave of the future. It should be noted that major changes in immigration since 2000 are likely to have significant effects on the number and percentages of elders in the US population. The effects from the Coronavirus COVID-19 pandemic that began in early 2020 are ongoing. The US Census Bureau is taking these changes into consideration in making population projections.

The significance of these increases in the number and proportion of older people is that the elderly will have an ever-greater influence on many aspects of society. As a group they will spend larger amounts of money, use more services, and have more political power. Therefore, an understanding of aging processes and other age-related changes is vital if society is to adapt to the changes that will accompany this phenomenon. Such an understanding may be especially important for those who, by virtue of their leadership positions, make decisions that have a broad impact, such as corporate and political decision makers.