Demographic shocks: the view from history: discussion

Massimo Livi-Bacci has taken us on a fascinating tour of demographic history. What lessons for developments in the world today can we draw from the story he tells? I will distinguish between three types of lessons, which I call "economic lessons," "demographic lessons," and "cultural/political lessons."Demography ; Economic conditions

Population Aging

Population aging is primarily the result of past declines in fertility, which produced a decades long period in which the ratio of dependents to working age adults was reduced. Rising old-age dependency in many countries represents the inevitable passing of this %u201Cdemographic dividend.%u201D Societies use three methods to transfer resources to people in dependent age groups: government, family, and personal saving. In developed countries, families are predominant in supporting children, while government is the main source of support for the elderly. The most important means by which aging will affect aggregate output is the distortion from taxes to fund PAYGO pensions.

Intergenerational Transfers, Aging, and Uncertainty

Research on intergenerational transmission of wealth has pointed to uncertainty -- about the date of one's own death, for example -- as a potential source of significant bequest flows. In this paper I examine the effects of this same uncertainty on the behavior of those who expect to receive bequests. Potential heirs who are prudent will consume less than would be warranted by the size of their expected bequests, and so on average consumption will rise at the age when actual bequests are received. I examine the effect of this uncertainty on the outcome of population aging. Population aging, by changing the relative sizes of the bequeathing generation and those receiving bequests, raises the average size of bequests received and reduces the saving of the bequest-receiving generation. I show that accounting for the effects of uncertainty slows down the reduction in saving that results from population aging.

The Baby Boom, The Baby Bust, and the Housing Market

This paper examines the impact of major demographic changes on the housing market in the United States. The entry of the Baby Boom generation into its house-buying years is found to be the major cause of the increase in real housing prices in the l97Os. Since the Baby Bust generation is now entering its house-buying years, housing demand will grow more slowly in the 1990s than in any time in the past forty years. If the historical relation between housing demand and housing prices continues into the future, real housing prices will fall substantially over the next two decades.

The Dynamics of the Age Structure, Dependency, and Consumption

We examine the dynamic interaction of the population age structure, economic dependency, and fertility, paying particular attention to the role of intergenerational transfers. In the short run, a reduction in fertility produces a %u201Cdemographic dividend%u201D that allows for higher consumption. In the long run, however, higher old-age dependency can more than offset this effect. To analyze these dynamics we develop a highly tractable continuous-time overlapping generations model in which population is divided into three groups (young, working age, and old) and transitions between groups take place in a probabilistic fashion. We show that most highly developed countries have fertility below the rate that maximizes steady state consumption. Further, the dependency-minimizing response to increased longevity is to raise fertility. In the face of the high taxes required to support transfers to a growing aged population, we demonstrate that the actual response of fertility will likely be exactly the opposite, leading to increased population aging.

Mortality Change, the Uncertainty Effect, and Retirement

We examine the role of changing mortality in explaining the rise of retirement over the course of the 20th century. We construct a model in which individuals make labor/leisure choices over their lifetimes subject to uncertainty about their date of death. In an environment in which mortality is high, an individual who saved up for retirement would face a high risk of dying before he could enjoy his planned leisure. In this case, the optimal plan is for people to work until they die. As mortality falls, however, it becomes optimal to plan, and save for, retirement. We simulate our model using actual changes in the US life table over the last century, and show that this 'uncertainty effect' of declining mortality would have more than outweighed the 'horizon effect' by which rising life expectancy would have led to later retirement. One of our key results is that continuous changes in mortality can lead to discontinuous changes in retirement behavior.

Saving and Growth: A Reinterpretation

We examine the relationship between income growth and saving using both cross-country and household data. At the aggregate level, we find that growth Granger causes saving, but that saving does not Granger cause growth. Using household data, we find that households with predictably higher income growth save more than households with predictably low growth. We argue that standard Permanent Income models of consumption cannot explain these findings, but that a model of consumption with habit formation may. The positive effect of growth on saving implies that previous estimates of the effect of saving on growth may be overstated.