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This post is a review of Prospective Longevity: A New Vision of Population Aging by Warren C. Sanderson and Sergei Scherbov.
In 2018, Emile Ratelband, a 69-year-old motivational speaker, asked a court in the Netherlands to change his official age. Ratelband argued that physically and mentally he was about 49. His chronological age, he added, subjected him to discrimination and reduced his odds of finding an appropriate partner on dating websites. A district court dismissed his suit.
Ratelband’s case may seem frivolous, but it reminds us that the physical and cognitive capabilities of older people have changed significantly in ways not captured by definitions of old age that are fixed at 60, 65, or 70. In Prospective Longevity, Warren Sanderson, an emeritus professor of economics at Stony Brook University, and Sergei Scherbov, Deputy Program Director at the World Population Program at the International Institute for Applied Systems Management, lay out a new approach to conceptualize and measure population aging that takes into account remaining life expectancy, functional ability, and variations across time, space, and population subgroups. Accepted by the Population Division of the United Nations (alongside conventional metrics), their benchmarks—the years we have left instead of the years we have already lived and the prospective old-age dependency ratio (POADR), which uses that threshold—have immense implications for data collection and public policy.
Prospective Longevity is, alas, not an easy read. The presentation of data is aimed at demographers, economists, and systems analysts, and not at general readers. And the authors beat their metaphor of seeing old age through old and new pairs of glasses into the ground. That said, they make a compelling case for a better way to answer the question, how old is old?
Sanderson and Scherbov set the old age threshold at the chronological age at which remaining life expectancy is 15 years. If statistics for men and women are combined, the number for 2018 is 73.9 in Japan, 71.5 in the United States, 66.6 in China, 65.5 in the Russian Federation, and 58.4 in Nigeria. This methodology changes the proportion of old people in these countries. The authors also conclude, albeit tentatively, that the quality of life (i.e. activity and health) in old age does not diminish as the prospective old age threshold increases.
Sanderson and Scherbov argue as well that public policies should be formulated based on characteristics that change over time rather than fixed chronological ages. They suggest, for example, that, “instead of lurching from one reform to another,” pensions should reflect intergenerational fairness: Individuals should receive sums approximating what they have paid in, getting the same proportion of their income after taxes. Economically disadvantaged pensioners might be subsidized by appropriating funds from people who die before they can collect their allotment. The authors acknowledge that their proposal does not account for changes over time in the cost of living. They maintain, however, “that the most important advantage” of their proposal is that it is understandable, grounded in “widely accepted principles,” and incorporates increases in life expectancy. And they ask readers to assess their admittedly “very simple” principle of intergenerational equity in the context of the maxim that “all models are wrong, but some are useful,” especially when they stimulate a fresh look at a pressing problem.
Between 2015 and 2030, the number of people in the world age 60 or older is projected to increase by 65 percent, from 901 million to 1.4 billion; by 2050, this cohort will reach nearly 2.1 billion. As the general strike in France reminds us, debates over government decisions about “old age” are increasingly contentious. Sanderson and Scherbov are surely right that we should not settle on solutions while “our vision of the demographic environment is occluded.”
