More Moderate Lifespan improvement

From: Robin Hanson (
Date: Thu Jun 15 2000 - 07:09:42 MDT

Today's issues of Nature has more forecasts of lifespan improvement
over the next fifty years based on trends over the last fifty years.
A USA lifespan of over 85 in 2050 would require a substantial
deviation from historical trends. Optimists be warned!

Nature 405:789-792 (2000)
"A universal pattern of mortality decline in the G7 countries"
Shripad Tuljapurkar, Nan Li & Carl Boe

Human lifespan has increased enormously this century. But we remain
uncertain about the forces that reduce mortality, and about the cost
implications of ageing populations and their associated social burden. The
poor understanding of the factors driving mortality decline, and the
difficulty of forecasting mortality are due in part to the pronounced
irregularity of annual to decadal mortality change. Here we examine
mortality over five decades in the G7 countries (Canada, France, Germany,
Italy, Japan, UK, US). In every country over this period, mortality at each
age has declined exponentially at a roughly constant rate. This trend places
a constraint on any theory of society-driven mortality decline, and provides
a basis for stochastic mortality forecasting. We find that median forecasts
of life expectancy are substantially larger than in existing official
forecasts. In terms of the costs of ageing, we forecast values of the
dependency ratio (that is, the ratio of people over 65 to working people) in
2050 that are between 6% (UK) and 40% (Japan) higher than official forecasts.

Robin Hanson
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323

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