tures affect the demand for public transfers of money, time, and living space? Will population aging lead to lower levels of aggregate saving, investment, and productivity growth? Will health care costs rise or decline relative to other costs?
Three other important features of population aging are also noteworthy. First, there are uncertainties about how some of the demographic forces will play out. For example, will increases in life expectancy accelerate with the development of new technology? Will persistent below-replacement fertility levels compel societies to alter immigration policies? How might the socioeconomic characteristics of tomorrow's elderly population differ from those of today? Second, because population aging generally is a gradual phenomenon, its socioeconomic consequences tend to appear gradually as well, and in some cases with a fair degree of predictability. Thus if policy makers recognize and appreciate the import of the coming changes, they will have a window of opportunity in which to develop policies and programs for coping with the stresses induced by changing population age structures. And third, most statements about aged individuals tend to reflect averages and mask a great deal of diversity in the population. For example, while a greater proportion of the elderly 1 than the nonelderly have some degree of disability, most of the elderly are not disabled. Likewise, there are prominent socioeconomic gradients among older populations in most countries that require explication and policy response.
As we move through the 21st century, countries around the world are apt to face slower growth (or even contraction) of the workforce, rapid increases in the over-65 and especially the over-80 population, potentially larger numbers of disabled persons and greater demand on health care systems, and the increase in poverty likely to accompany rising numbers of widows. Many countries are now in the early stages of adapting to their changing population age structures. Since current and prospective policy responses are likely to differ among countries, a number of natural experiments are, or shortly will be, under way, enabling countries to learn from each other's experience. To take advantage of this opportunity, the U.S. National Institute on Aging asked the National Academies, through its National Research Council, to convene a panel that would provide recommendations for an international research agenda and for the types of data needed to implement that agenda in the context of rapid demographic change.
1There is a growing awareness that the category “elderly” is an inadequate generalization that conceals the diversity of a broad age group spanning more than 40 years of life. For cross-national comparative purposes, however, some chronological demarcation of age categories is required. In this report, the term “elderly” refers to persons aged 65 and over, and the term “oldest old” to persons aged 80 and over.