[tt] Science: Jim Oeppen and James W. Vaupel: Broken Limits to Life Expectancy

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Jim Oeppen and James W. Vaupel: Broken Limits to Life Expectancy
Science 02.5.10: Vol. 296. no. 5570, pp. 1029 - 1031

Is life expectancy [HN1] approaching its limit? Many--including
individuals planning their retirement and officials responsible for
health and social policy--believe it is. The evidence suggests
otherwise.

Consider first an astonishing fact. Female life expectancy in the
record-holding country has risen for 160 years at a steady pace of
almost 3 months per year [Fig. 1 and suppl. table 1 (1)]. In 1840 the
record was held by Swedish women, who lived on average a little more
than 45 years. Among nations today, the longest expectation of
life--almost 85 years--is enjoyed by Japanese women [HN2]. The
four-decade increase in life expectancy in 16 decades is so
extraordinarily linear [r2 = 0.992; also see suppl. figs. 1 to 5 (1)]
that it may be the most remarkable regularity of mass endeavor ever
observed. Record life expectancy has also risen linearly for men (r2 =
0.980), albeit more slowly (slope = 0.222): the gap between female and
male levels [HN3] has grown from 2 to 6 years (suppl. fig. 2).

Figure 1
Fig. 1. Record female life expectancy from 1840 to the present [suppl.
table 2 (1)]. The linear-regression trend is depicted by a bold black
line (slope = 0.243) and the extrapolated trend by a dashed gray line.
The horizontal black lines show asserted ceilings on life expectancy,
with a short vertical line indicating the year of publication (suppl.
table 1). The dashed red lines denote projections of female life
expectancy in Japan published by the United Nations in 1986, 1999, and
2001 (1): It is encouraging that the U.N. altered its projection so
radically between 1999 and 2001.

In addition to forewarning any looming limit to the expectation of
life, trends in best-practice life expectancy provide information
about the performance of countries. The gap between the record and the
national level is a measure of how much better a country might do at
current states of knowledge and demonstrated practice. Although rapid
progress in catch-up periods typically is followed by a slower rise,
life-expectancy trajectories do not appear to be approaching a maximum
(Fig. 2).

Figure 2
Fig. 2. Female life expectancy in Chile, Japan, New Zealand
(non-Maori), Norway, and the United States compared with the trend in
record life expectancy.

The linear climb of record life expectancy suggests that reductions in
mortality should not be seen as a disconnected sequence of
unrepeatable revolutions but rather as a regular stream of continuing
progress (2, 3). Mortality improvements [HN4] result from the
intricate interplay of advances in income, salubrity, nutrition,
education, sanitation, and medicine, with the mix varying over age,
period, cohort, place, and disease (4). Before 1950, most of the gain
in life expectancy was due to large reductions in death rates at
younger ages. In the second half of the 20th century, improvements in
survival after age 65 propelled the rise in the length of people's
lives. For Japanese females, remaining life expectancy at age 65 grew
from 13 years in 1950 to 22 years today, and the chance of surviving
from 65 to 100 soared from less than 1 in 1000 to 1 in 20 (1). The
details are complicated but the resultant straight line of
life-expectancy increase is simple.

World life expectancy more than doubled over the past two centuries,
from roughly 25 years to about 65 for men and 70 for women (4). This
transformation of the duration of life greatly enhanced the quantity
and quality of people's lives. It fueled enormous increases in
economic output and in population size, including an explosion in the
number of the elderly [HN5] (5, 6). Although students of mortality
eventually recognized the reality of improvements in survival, they
blindly clung to the ancient notion that under favorable conditions
the typical human has a characteristic life-span. As the expectation
of life rose higher and higher, experts were unable to imagine its
rising much further. They envisioned various biological barriers and
practical impediments. The notion of a fixed life-span evolved into a
belief in a looming limit to life expectancy.

Ultimate Expectations of Life

In 1928, Louis Dublin quantified this consensus (7). Using U.S. life
tables as a guide, he estimated the lowest level to which the death
rate in each age group could possibly be reduced. His calculations
were made "in the light of present knowledge and without intervention
of radical innovations or fantastic evolutionary change in our
physiological make-up, such as we have no reason to assume." His
"hypothetical table promised an ultimate figure of 64.75 years" for
the expectation of life both for males and for females. At the time,
U.S. life expectancy was about 57 years. Because Dublin did not have
data for New Zealand, he did not realize that his ceiling had been
pierced by women there: in the non-Maori life table for 1921, female
life expectancy is 65.93 years [Fig. 1 and suppl. tables 1 and 2 (1)].

Marshalling methods and arguments strikingly similar to Dublin's,
Olshansky et al. in 1990 and again in 2001 [HN6] assess the life
expectancy that could be attained if age-specific death rates could be
reduced by amounts that are not "implausible," "overly optimistic,"
and "highly unlikely" (8, 9). In 1990, they asserted that life
expectancy "should not exceed ... 35 years at age 50 unless major
breakthroughs occur in controlling the fundamental rate of aging."
This cap, however, was surpassed by Japanese females in 1996.

Other scholars tried various stratagems to seize life expectancy
heights that they could not conceive of being surmounted (1). Although
some of the more recent ostensible limits have not yet been exceeded,
those from Dublin in 1928 to Olshansky et al. in 1990 have been
broken, on average 5 years after publication (Fig. 1 and suppl. table 1).

Better Forecasts

The ignominious saga of life-expectancy maxima is more than an
exquisite case for historians intrigued by the foibles of science.
Continuing belief in imminent limits is distorting public and private
decision-making. Forecasts of the expectation of life [HN7] are used
to determine future pension, health-care, and other social needs.
Increases in life expectancy of a few years can produce large changes
in the numbers of the old and very old, substantially augmenting these
needs (5, 6). The officials responsible for making projections have
recalcitrantly assumed that life expectancy will increase slowly and
not much further (10). The official forecasts distort people's
decisions about how much to save and when to retire. They give
politicians license to postpone painful adjustments to social-security
and medical-care systems (11).

Officials charged with forecasting trends in life expectancy over
future decades should base their calculations on the empirical record
of mortality improvements over corresponding spans of the past (2, 3).
Because best-practice life expectancy has increased by 2.5 years per
decade for a century and a half, one reasonable scenario would be that
this trend will continue in coming decades. If so, record life
expectancy will reach 100 in about six decades. This is far from
eternity: modest annual increments in life expectancy will never lead
to immortality. It is striking, however, that centenarians may become
commonplace within the lifetimes of people alive today (12).

Life expectancy can be forecast by considering the gap between
national performance and the best-practice level (Fig. 2). The U.S.
disadvantage varied from a decade in 1900 to less than a year in 1950
and about 5 years in 2000 (Fig. 2). If the trend in record life
expectancy continues and if the U.S. disadvantage is between a year
and a decade in 2070, then female life expectancy would be between
92.5 and 101.5, considerably higher than the Social Security
Administration's forecast of 83.9 published in 1999 (1). An
alternative method for forecasting life expectancy is to analyze the
rapidity of improvement in age-specific death rates over many decades
and then to use this information to project death rates over coming
decades (2, 3). The official Japanese forecast, issued in 1997, of
life expectancy (for males and females combined) in 2050 is 82.95 (1).
Projections based on the decline in death rates in Japan since 1950
result in a life expectancy some 8 years longer, 90.91, with a 90%
confidence range from 87.64 to 94.18 (3).

Declines in mortality might be systematically slower than in the past.
On the other hand, biomedical research may yield unprecedented
increases in survival. Given the extraordinary rise in best-practice
life expectancy and the demonstrated nearsightedness of expert vision,
the central forecast should be based on the long-term trend of
sustained progress in reducing mortality.

In their quest to impose a cap on average longevity, students of
mortality ignored essential research questions. Major changes in life
expectancy hinge on improvements in survival at advanced ages, but
comprehensive analysis of the substantial reductions since the
mid-20th century in death rates after age 80 first flourished in the
1990s (1, 13). Hypothesized biological barriers to longer life-spans
also first received systematic attention (and refutation) a decade ago
(1, 14-16). The impact of continuing mortality improvements on life
expectancy attracted empirical (12) and theoretical attention (17) in
the late 1980s, with refined methods developed over the past decade
(1-3).

Three Findings

This mortality research has exposed the empirical misconceptions and
specious theories that underlie the pernicious belief that the
expectation of life cannot rise much further. Nonetheless, faith in
proximate longevity limits endures, sustained by ex cathedra
pronouncement and mutual citation (1, 8, 9). In this article we add
three further lines of cogent evidence. First, experts have repeatedly
asserted that life expectancy is approaching a ceiling: these experts
have repeatedly been proven wrong. Second, the apparent leveling off
of life expectancy in various countries is an artifact of laggards
catching up and leaders falling behind. Third, if life expectancy were
close to a maximum, then the increase in the record expectation of
life should be slowing. It is not. For 160 years, best-performance
life expectancy has steadily increased by a quarter of a year per
year, an extraordinary constancy of human achievement.

References and Notes

1. Supplemental material--including data sources and additional
references--is available on Science Online at
http://www.sciencemag.org/cgi/content/full/296/5570/1029/DC1. Life
expectancy is the mean age at death under current mortality
conditions.
2. R. D. Lee, L. Carter, J. Am. Stat. Assoc. 87, 659 (1992).
3. S. Tuljapurkar, N. Li, C. Boe, Nature 405, 789 (2000).
4. J. Riley, Rising Life Expectancy: A Global History (Cambridge
Univ. Press, Cambridge, 2001), 243 pp.
5. L. G. Martin, S. H. Preston, Demography of Aging (National
Academy Press, Washington, DC, 1994).
6. R. W. Fogel, D. L. Costa, Demography 34, 49 (1997).
7. L. I. Dublin, Health and Wealth (Harper, New York, 1928), 361 pp.
8. S. J. Olshansky, B. A. Carnes, C. Cassel, Science 250, 634 (1990).
9. S. J. Olshansky, B. A. Carnes, A. Désesquelles, Science 292, 1654 (2001).
10. N. Keilman, J. Offic. Stat. 12, 245 (1997).
11. J. W. Vaupel, Washington Q. 23, 197 (2000).
12. J. W. Vaupel, A. E. Gowan, Am. J. Public Health 76, 430 (1986) .
13. V. Kannisto, J. Lauritsen, A.R. Thatcher, J.W. Vaupel, Pop. Dev.
Rev. 20, 793 (1994).
14. J. R. Carey, P. Liedo, D. Orozco, J. W. Vaupel, Science 258, 457
(1992).
15. J. W. Curtsinger, H. H. Fukui, D. Townsend, J. W. Vaupel,
Science 258, 461 (1992).
16. J. W. Vaupel et al., Science 280, 855 (1998).
17. J. W. Vaupel, Pop. Stud. 40, 147 (1986).
18. Funded by the Max Planck Society and the U.S. National Institute
on Aging (AG-08761). We thank V. Kannisto, P. Laslett, S. Horiuchi, 
R.
D. Lee, S. Leek, H. Maier, M. Luy, R. Rau, Y. Saito, S. Tuljapurkar,
K. W. Wachter, and J. R. Wilmoth for their assistance.

J. Oeppen is with the Cambridge Group for the History of Population
and Social Structure, Cambridge University, Cambridge, CB2 3EN, UK. He
is associated with, and J. W. Vaupel is at, the Max Planck Institute
for Demographic Research, Doberaner Strasse 114, D-18057 Rostock,
Germany.

To whom correspondence should be addressed. E-mail: jwv at demogr.mpg.de

HyperNotes

Related Resources on the World Wide Web

General Hypernotes

Dictionaries and Glossaries

The Glossary of Population Terms, made available by the Population
Reference Bureau, includes definitions of concepts related to
demographics, mortality, and life expectancy.

The United Nations Population Information Network offers a
Dictionary of Demographic and Reproductive Health Terminology.

Web Collections, References, and Resource Lists

The Open Directory Project has compiled links to Internet
resources on demography and population studies.

The Max Planck Institute for Demographic Research site features a
selection of demography links.

The Web site of the Population Reference Bureau, a nonprofit
provider of worldwide information on population and demographics,
offers general information on population trends, mortality, and a
wealth of other topics. The Bureau's PopNet browser organizes a
comprehensive set of population-related links by institution, country,
and topic.

The International Programs Center of the U.S. Census Bureau offers
a searchable International Data Base (IDB) of population and
demographic information and projections (including mortality and life
expectancy data).

The World Wide Web Virtual Library on Demography and Population
Studies points to a variety of Internet resources on demographic data
sources and information.

H-DEMOG, the Web site of the Historical Demography Internet
discussion group, includes a page of links to demography Web
resources.

The Population Studies Center at the University of Michigan
maintains a collection of Internet resources on issues of
demographics, aging, mortality, and population.

The Sharlin Demography Library of the U.C. Berkeley Department of
Demography offers a convenient list of pointers to demography Web
resources.

The Population & Environment Linkages Service, hosted by the
National Council for Science and the Environment, provides links to
information (much of it culled from the International Data Base of the
U.S. Census Bureau) on worldwide demographics, current and projected
life expectancy values, and health policy.

The Center for Human Resource Research at Ohio State University
offers a collection of Internet Resources for Demographers.

The Netherlands Interdisciplinary Demographic Institute provides
the World Wide Web of Demography, a wide-ranging collection of online
resources.

General Reports and Articles

The Population Index Web site, from Princeton University's Office
of Population Research, provides a searchable and browsable database
containing more than 45,000 abstracts of demographic literature
published since 1986.

Population Handbook [PDF], a general introduction to population
dynamics and demographic data from the Population Reference Bureau,
includes sections explaining life tables, life expectancy, and
mortality rates.

Between Zeus and the Salmon: The Biodemography of Longevity, from
the Committee on Population of the National Research Council, examines
"what biology and demography have to tell and ask each other about
human longevity," and touches upon some of the themes explored in this
policy forum.

Longevity Records, a study of the life spans of a variety of fish,
reptile, amphibian, bird, and mammal species (including Homo sapiens),
is made available online at the Max Planck Institute for Demographic
Research site. Also posted at the institute site is an online edition
of Exceptional Longevity: From Prehistory to the Present, a monograph
exploring the evolution of human longevity over time.

"Biodemographic trajectories of longevity," a review article by J.
W. Vaupel et al. in the 8 May 1998 issue of Science, explores the
possible causes of the substantial increase in old-age survival since
1950.

Demographic Research is a free, peer-reviewed online journal
published by the Max Planck Institute for Demographic Research.

Population Today is a newsletter posted by the Population
Reference Bureau.

Numbered Hypernotes

1. Life expectancy. A wide range of Web sites (in addition to the
supporting online material accompanying this policy forum) provide
basic data on worldwide life expectancy. Among them: The Berkeley
Mortality Database, developed by J. R. Wilmoth, offers life tables,
birth and death rate data, and historical life expectancy figures for
France, the U.S., Sweden, and Japan, drawn from census data and vital
statistics. The National Center for Health Statistics of the U.S.
Centers for Disease Control and Prevention publishes historical life
expectancy data for the United States. Statistics Canada maintains
current and historical information about life expectancy at birth by
gender and province. The World Population Data Sheet of the Population
Reference Bureau presents global data on current life expectancy by
country and gender. The Global Terrestrial Observing System (GTOS) of
the U.N. Food and Agriculture Organization offers a capsule summary
[PDF] of the concept of life expectancy and the principal sources for
worldwide data. An article posted by the Population Reference Bureau
titled "How much better can it get?" briefly outlines the debate
between researchers who argue for and against fundamental biological
limits on human life expectancy.

2. Life expectancy in Japan. Data on Japanese life expectancy can
be found in the database pages of the Japanese Ministry of Health,
Labor, and Welfare, which offer detailed life tables for Japan, along
with information on historical trends in the five leading causes of
death and other information. Japanese government predicitions of the
country's future population, along with the life expectancy
assumptions that those predictions embody, can be downloaded at the
Web site of the National Institute of Population and Social Security
Research.

3. Differences between female and male life expectancy. In The
World's Women 2000: Trends and Statistics, the United Nations
Statistics Division provides a worldwide summary table of life
expectancy and infant mortality for females and males. Historical data
on life expectancy by age for males and females in the U.S., covering
the period from 1850 to 1999, can be found on the InfoPlease site.
"Around the globe, women outlive men," an article from the
August/September 2001 issue of Population Today, offers a color-coded
global map of differences between male and female longevity and some
notes on the reasons for the difference; another article from the
Population Reference Bureau discusses the causes of the gender gap in
U.S. mortality.

4. Mortality and mortality improvements. The National Academy Press
publication Beyond Six Billion: Forecasting the World's Population
includes a chapter on mortality that explores the causes of historical
increases in mortality and of the differences in mortality increase
between different societies. World Population Beyond Six Billion, a
report presented by the Population Reference Bureau, discusses in some
detail the long-term changes in population patterns since before 1900
and the nature and causes of historical mortality declines.

5. Implications of an aging population. Institutions focused on the
demography of aging include (among many others) the National Institute
on Aging, the Administration on Aging of the U.S. Department of Health
and Human Services, the University of Pennsylvania's Population Aging
Research Center, and the Michigan Center on the Demography of Aging.
Several publications of the National Academy Press, including
Preparing for an Aging World (2001) and Demography of Aging (1994),
deal with the aging of the worldwide population from demographic and
policy perspectives. A 10 March 2001 article in Science News titled
"Making sense of centenarians" describes the increase in
100-plus-year-old members of the population, and the lifestyle,
health, and genetic factors that may be contributing to that increase.
Aging in the Americas into the XXI Century, a wall chart offered in
PDF form from the National Institute on Aging and the U.S. Census
Bureau, provides graphic information on the changing age structure in
North, Central, and South America and the implications of those
changes. The Population Reference Bureau has posted a variety of
reports and articles on the older population, including Elderly
Americans, a study that overviews the demographic characteristics and
profound social, health, and economic impacts of the rapidly aging
population in the U.S.

6. Previous discussion in Science. The issue of whether there are
limits to life expectancy has a long pedigree of discussion in
Science. In the 2 November 1990 issue, S. J. Olshansky, B. A. Carnes,
and C. Cassel published "In search of Methuselah: Estimating the upper
limits to human longevity," which argued that fundamental limits to
life expectancy are likely (AAAS members can gain access to the full
text of that article through the JSTOR link on the membership portal
AAASmember.org). J. R. Wilmoth, in "The future of human longevity: A
demographer's perspective" in the 17 April 1998 issue, held that
extrapolation of the long-term, stable declines in mortality suggested
a continued rise in life expectancy, an assertion disputed in
subsequent letters by L. Gavrilov and N. Gavrilova and by S. J.
Olshansky et al. "Prospects for Human Longevity," a Policy Forum by S.
J. Olshansky, B. A. Carnes, and A. Désesquelles published in the 23
February 2001 issue, once again argued for fundamental biological
limits to human life span; that article was discussed in a letter
exchange with R. Lee.

7. Life expectancy forecasts. The World Population Prospects
Population Database of the United Nations Population Information
Network lets users query the U.N.'s international forecasts for a
variety of population indicators, including life expectancy and
percent of population in various age cohorts, through 2050. A document
presenting the results of the 1996 population projection, provided by
the Austria-based International Institute for Applied Systems
Analysis, includes a discussion of the assumptions about mortality
that factor into such estimates. World Population Futures, presented
by the Population Reference Bureau, provides a thorough and useful
overview of how future population is forecast and, in particular, of
the uncertainties involved in projections of future mortality and life
expectancy.

8. J. Oeppen is with the Cambridge Group for the History of
Population and Social Structure, Department of Geography, University
of Cambridge, and is associated with the Max Planck Institute for
Demographic Research.

9. J. W. Vaupel is at the Max Planck Institute for Demographic
Research.

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Supplementary Material
This supplementary material is organized as follows:

* Data sources
* A brief history of life-expectancy limits, with references
* Further arguments and evidence about life-expectancy limits
* Supplementary figures 1 to 5
* Supplementary tables 1 and 2

Data Sources

Statistics in this article are from
http://www.demog.berkeley.edu/wilmoth/mortality,
http://www.mhlw.go.jp/english/database/index.html, N. Keyfitz and W.
Flieger, World Population: An Analysis of Vital Data (Univ. of Chicago
Press, Chicago, 1968); S. H. Preston, N. Keyfitz and R. Schoen, Causes
of Death: Life Tables for National Populations (Seminar Press, New
York, 1972); and life table collections at the Cambridge Group for the
History of Population and Social Structure and the Max Planck
Institute for Demographic Research. For further information about
online data available from the Max Planck Institute, see
http://www.demogr.mpg.de.

A Brief History of Life-Expectancy Limits, with References

Purported limits to life expectancy and the years when they were
broken are summarized in Fig. 1 of the main text and in supplementary
table 1. The following paragraphs provide some context and supply
references not given in the main text.

Louis Dublin, who became Chief Actuary of the Metropolitan Life
Insurance Company, seems to have been the first demographer to publish
a reasoned estimate of a ceiling to life expectancy. As noted in the
main text, when he published his limit in 1928 it had already been
breached by non-Maori women in New Zealand.

In 1936, joined by Alfred Lotka, the creator of modern mathematical
demography, Dublin assessed a revised life-expectancy limit using data
for New Zealand, as well as for the United States [L. I. Dublin, A. J.
Lotka, Length of Life: A Study of the Life Table (Ronald Press, New
York, 1936), p. 193]. Dublin and Lotka's "hypothetical table promises
an eventual expectation of life at birth of 69.93 years." Women on
Iceland surpassed this maximum in 1941. Trying yet again, Dublin
published in 1941 a third ostensible cap: 70.8 years [reported in his
memoirs: L. I. Dublin, The Facts of Life: From Birth to Death
(Macmillan, New York, 1951), p. 392]. Women in Norway broke this limit
in 1946.

Dublin's memoirs suggest that revising the ceiling upward was a
feature of his career with the Metropolitan Life Insurance Company. As
he observed half a century ago, "experience has shown that our
optimistic views regarding prospects for improved longevity are
generally conservative."

As noted in the main text, Olshansky and colleagues used methods and
rhetoric similar to Dublin's to estimate limits to life expectancy. In
addition to their articles in Science cited in note (8, 9) of the main
text, they have written a book: S. J. Olshansky, B. A. Carnes, The
Quest for Immortality (Norton, New York, 2001). See J. R. Wilmoth,
Pop. Dev. Rev. 27, 791 (2001) for a critical review.

Jean Bourgeois-Pichat [Population 3, 381 (1952) and Pop. Bull. U.N.
11, 12 (1978)] classified deaths into extrinsic causes that
potentially could be eliminated and intrinsic causes that could not;
he calculated a life table with the extrinsic causes excluded.
Similarly, James F. Fries [Milbank Q. 67, 208 (1990) and N. Engl. J.
Med. 303, 130 (1980)] distinguished between premature mortality, which
is tractable, and senescent mortality, which is not.

P. K. Whelpton identified the lowest age-specific death rates at each
age in various countries and estimated life expectancy if a population
enjoyed best-practice rates at all ages: see P. K. Whelpton, Forecasts
of the Population of the United States 1945-1975 (Bureau of the
Census, Washington, DC, 1947), a report notorious for missing the baby
boom. Whelpton focused his discussion on life-expectancy limits for
U.S. native-born white males. He concluded that for this population a
life expectancy in the year 2000 of 72.1 years was the upper limit of
what could be achieved by the largest mortality "declines that seem
reasonable" and close to what could be attained at the "biological
minimum of mortality."

Jacob S. Siegel [NIH Publ. 80-969 (National Institutes of Health,
Bethesda, MD, 1980), pp. 17-82] carried Whelpton's general approach a
step further by estimating life expectancy on the basis of
best-practice cause-specific and age-specific rates. See A. Nizard and
J. Vallin, Population 25, 847 (1970); G. Wunsch, Eur. Demogr. Infor.
Bull. 5(1), 2 (1974); and K. Uemura, World Health Stat. Q. 42, 26
(1989) for calculations similar to Whelpton's and Siegel's.

Whelpton assumed that mortality improvements would decelerate as an
ultimate cap was approached. This notion was later used by Tomas
Frejka [The Future of Population Growth (Wiley, New York, 1973) and
Pop. Dev. Rev. 7, 489 (1981)]. Both these publications focus on
population growth rather than life expectancy. In the first, Frejka
writes, "within broad limits mortality can be fairly well predicted."
He believes that life expectancy will approach a limit and that 77.5
is the most likely limit. He notes, however, that "mortality might
even take a course absolutely different from what has been assumed."

Other forecasts in which life expectancy asymptotically approaches a
limit include projections by the World Bank [P. Demeny, Pop. Dev. Rev.
10, 103 (1984); R. A. Bulatao and E. Bos, Policy Research Working
Paper 337 (World Bank, Washington, DC, 1989)]; and the United Nations
(United Nations, World Population Prospects (New York, various years
including 1973, 1986, 1989, 1999, 2001).

In most such asymptotic forecasts, judgment, rather than empirical
calculation, is used to specify the maximum life expectancy. Research
by the eminent demographer Ansley J. Coale provides a notable
exception. Coale [IUSSP Int. Conf. Manila 4, 35 (1981); A. J. Coale
and G. Guo, Pop. Bull. U.N. 30, 1 (1991)] tried to empirically
estimate the upper limit of life expectancy by fitting an asymptotic
function.

An account of official life-expectancy projections before 1970 is
provided by Samuel H. Preston, World Health Stat. Rep. 27, 719 (1974).

H. Cruijsen and H. Eding [in E. Tabeau, A. van den Berg Jeths, and C.
Heathcote, Eds., Forecasting Mortality in Developed Countries (Kluwer
Academic, Dordrecht, Netherlands, 2001), p. 243] review mortality
forecasting in 13 European Union countries in the early and mid 1990s.
They found that all assumed mortality improvements would decelerate
and 10 constrained life expectancy to reach an ultimate limit by a
target date.

For recent forecasts for Japan, see National Institute of Population
and Social Security Research, Population Projection of Japan,
1996-2050 (Tokyo, 1997) and
http://www.ipss.go.jp/English/ppfj02/top.html. For a recent U.S.
forecast, see Board of Trustees, Social Security Administration, 1999
Annual Report (Government Printing Office, Washington, DC, 1999).
Ronald D. Lee [Pop. Dev. Rev. 26, 137 (2000)] provides a critical
account of the low mortality assumptions used by the U.S. Social
Security Administration.

In the early 1940s, when he was a student at Princeton University,
Ansley Coale developed and applied a method that computed the average
rapidity of improvement in age-specific death rates over many decades
and then used this information to project death rates over coming
decades [F. W. Notestein, I. B. Taeuber, D. Kirk, A. J. Coale, L. K.
Kiser, The Future Population of Europe and the Soviet Union (League of
Nations, Geneva, 1944), pp. 5, 183-189]. Today vastly superior data
resources are available and powerful, practicable methods have been
developed to do more than Coale attempted. These methods use
information about fluctuations in the speed of change in the past to
estimate confidence bounds for the uncertainty enveloping life
expectancy in the future. See references (2) and (3) of the main text
and J. Alho, Rev. Stat. Finland 4, 1 (1998).

For further information about methods for forecasting life expectancy,
see J. R. Wilmoth, Science 280, 395 (1998); J. W. Vaupel, Science 280,
986 (1998); J. Bongaarts, R. A. Bulato, Eds., Beyond Six Billion:
Forecasting the World's Population (National Academy Press,
Washington, DC, 2000); W. Lutz, W. Sanderson, S. Scherbov, Nature 412,
543 (2001); and J. Bongaarts and G. Feeney, Pop. Dev. Rev. 28, 234
(2002). S. J. Olshansky, B. A. Carnes, and A. Désesquelles [Science
292, 1654 (2001)] use changes in age-specific probabilities of death
over the decade from 1985 to 1995 to make long-term projections, one
out to the year 2577. It is more appropriate to base long-term
projections on long-term historical data and to use changes in central
death rates. See R. D. Lee, Science 292, 1654 (2001), as well as the
references given above.

For information about record longevity, see B. Jeune and J. W. Vaupel,
Eds., Exceptional Longevity (Odense Univ. Press, Denmark, 1995) online
at http://www.demogr.mpg.de/Papers/Books/Monograph2/start.htm; B.
Jeune and J. W. Vaupel, Eds., Validation of Exceptional Longevity
(Odense Univ. Press, Denmark, 1999); and J. R. Wilmoth, L. J. Deegan,
J. Lundstrom, and S. Horiuchi, Science 289, 2366 (2000).

Further Arguments and Evidence about Life-Expectancy Limits

S. J. Olshansky, B. A. Carnes, and A. Désesquelles [Science 292, 1654
(2001)] emphasize a theoretical barrier to longer life expectancy:
"entropy in the life table means that small but equal incremental
gains in life expectancy require progressively larger reductions in
mortality.... Projections based on biodemographic principles that
recognize the underlying biology within the life table would lead to
more realistic forecasts of life expectancy that reflect the
demographic reality of entropy in the life table." Entropy in the life
table is merely the statistic -Integration Symbols(a,t)ln
s(a,t)da/Integration Symbols(a,t)da, where s(a,t) is the probability
of surviving from birth to age a at age-specific death rates
prevailing at time t. Contrary to Olshansky et al.'s claim, in
countries with long life expectancies a continuing rate of decline in
age-specific death rates of N percent per year will increase life
expectancy at birth by about N years per decade [J. W. Vaupel, Pop.
Stud. 40, 147 (1986); J. W. Vaupel and V. Canudas Romo, in E. J.
Docker et al., Eds., Optimization, Dynamics, and Economic Analysis:
Essays in Honor of Gustav Feichtinger (Physica Verlag, New York,
2000), pp. 345-352, online at
http://www.demogr.mpg.de/Papers/Working/wp-1999-015.pdf]. Note that
steady rates of change in mortality levels produce steady absolute
increases in life expectancy: This relationship may underlie the
linear trend of record life expectancy. In any case, valid
biodemographic principles impose no insurmountable barriers to longer
lives. See references in note (14-16) of the main text of this article
and K. W. Wachter, C. E. Finch, Eds., Between Zeus and the Salmon: The
Biodemography of Longevity (National Academy Press, Washington, DC,
1997); J. R. Carey, D. S. Judge, Pop. English Select. 13, 9 (2001);
and J. R. Carey, D. S. Judge, Pop. Dev. Rev. 27, 411 (2001).

If the expectation of life in developed countries were approaching an
imminent maximum, then the pace of improvement in mortality in the
countries with the highest life expectancies would be slower than the
pace in countries with shorter life expectancies. There is, however,
no correlation between the level of life expectancy and the pace of
improvement. Indeed, in the current life-expectancy leader, Japan,
death rates are falling exceptionally rapidly. Furthermore, as life
expectancy rose over the course of the 20th century, the pace of
mortality improvement at older ages accelerated. Even after age 100,
death rates are falling. Female life expectancy is higher than the
male level in long-lived countries, but female life expectancy is
increasing somewhat more rapidly. See reference (13) of the main text
and V. Kannisto, Development of Oldest-Old Mortality, 1950-1990
(Odense Univ. Press, Denmark, 1994) online at
http://www.demogr.mpg.de/Papers/Books/Monograph1/OldestOld.htm; V.
Kannisto, The Advancing Frontier of Survival (Odense Univ. Press,
Denmark, 1996) online at
http://www.demogr.mpg.de/Papers/Books/Monograph3/The_advancing.htm; A.
R. Thatcher, V. Kannisto, J. W. Vaupel, The Force of Mortality at Ages
80 to 120 (Odense Univ. Press, Denmark, 1998), online at
http://www.demogr.mpg.de/Papers/Books/Monograph5/ForMort.htm; J. W.
Vaupel, Philos. Trans. R. Soc. London B 352, 1799 (1997); and J. R.
Wilmoth, in K. W. Wachter and C. E. Finch, Eds., Between Zeus and the
Salmon: The Biodemography of Longevity (National Academy Press,
Washington, DC, 1997).

The conventional view is that "future gains in life expectancy cannot
possibly match those of the past, because they were achieved primarily
by saving the lives of infants and children-something that happens
only once for a population" [S. J. Olshansky, B. A. Carnes, and A.
Désesquelles, Science 292, 1654 (2001)]. The sustained improvement in
best-practice life expectancy belies this contention.

Reinforcing processes may help sustain the increase in record life
expectancy. For instance, the decline in childhood diseases may lead
to fitter adults and fewer premature deaths may reduce bereavement
effects, an important risk factor for mortality. The improvements also
increase the number of people who survive to be elderly, leading to
greater attention to health at those ages. Increasingly prosperous,
educated populations aided by armies of researchers, physicians,
nurses, and public-health workers incessantly seize opportunities to
push death back. Economy, politics, and society may adapt to reflect
the changing age-structure of the population.

This argument was proposed by Tuljapurkar et al. in seeking to explain
the universal pattern of mortality decline in the richest countries
over the past 50 years [reference (3) in main text]. They highlight
"the roughly constant long-run exponential rates of decline" in
age-specific death rates and seek to explain this remarkable "linear"
(i.e., on a log scale) pattern of decline. Their work provides another
critique of the pessimism of mortality forecasts and suggests that the
exponential increase in national income per capita in advanced
countries may have been enough to offset the increasing marginal costs
of reducing morbidity and death.

Note, however, that while the United States may be one of the richest
countries in the world, it has not been the healthiest. Similarly high
levels of life expectancy are now enjoyed by much poorer countries,
such as Chile and Costa Rica. International transfers of health
technology over the past century have contributed to both rising and
converging life expectancy around the globe [C. Wilson, Pop. Dev. Rev.
28, 234 (2001)]..

Supplemental Figure 1. Female life expectancy in the record-holding
country, based on the annual data shown in supplementary table 1. The
fitted trend has a slope of 0.243 and r2 = 0.982.

Supplemental Figure 2. Male (blue squares) and female (red circles)
life expectancy in the record-holding country, based on the annual
data shown in supplementary table 1. For males the fitted line has a
slope of 0.222 and r2 = 0.980.

Supplemental Figure 3. Female life expectancy in the record-holding
country (bold red circles) and in the second-best country (green
circles), based on the annual data shown in supplementary table 1. The
line for second-best life expectancy has a slope of 0.260 and r2 =
0.979.

Supplemental Figure 4. Male life expectancy in the record-holding
country (bold blue squares) and in the second-best country (green
squares), based on the annual data shown in supplementary table 1. The
line for second-best life expectancy has a slope of 0.240 and r2 =
0.975.

Supplemental Figure 5. Female life expectancy in the record holding
country based on the simplified data shown in supplementary table 1 as
well as additional data for years before 1840. The data before 1840
pertain to nonmetropolitan parishes in England [E. A. Wrigley et al.,
English Population History from Family Reconstitution: 1580-1837
(Cambridge Univ. Press, Cambridge, 1997)]. Available national data on
life expectancy in Denmark, Norway and Sweden before 1840 suggest that
female life expectancy in these countries was similar to that in
England. For Sweden, see the Human Mortality Database
http://www.demog.berkeley.edu/wilmoth/mortality or
http://www.demogr.mpg.de.. For Denmark, see H. C. Johansen and J.
Oeppen, Danish Population Estimates 1665-1840, Research Report 21,
Danish Center for Demographic Research, Odense, Denmark.

Supplemental Table 1. Estimates of maximum average longevity for
females. Limits pertain to female life expectancy at birth, with two
exceptions (*). Fries asserted that if all premature death were
eliminated, ages at death would follow a normal distribution with a
mean of 85 and a standard deviation that he gave as 5 in 1980 and as 7
in 1990. In normal distributions, the mode and median equal the mean.
The modal (i.e., most common) age of death was 86 in the 1985 Japanese
female life table. The median age of death exceeded 85 in the 1994
life table and the mean age of death after age 50 exceeded 85 in the
1996 life table. For Olshansky et al., the value of 85 shown in this
table is 50 plus remaining life expectancy at age 50, which they
assert will not exceed 35 years. The text of their article implies
that this assertion holds for women as well as for men. The maxima set
by Dublin, Dublin and Lotka, Siegel, and Fries also hold for both men
and women, whereas the other limits given in this table hold for women
only: male caps are lower. References are given in the Supplemental
Material, above.
Source Limit* Date published Date exceeded Exceeded by females in

Dublin 64.8 1928 1921 New Zealand
Dublin and Lotka 69.9 1936 1941 Iceland
Dublin 70.8 1941 1946 Norway
Bourgeois-Pichat 78.2 1952 1974 Iceland
Coale 84.2 1955 2000 Japan
United Nations 77.5 1973 1972 Sweden
Bourgeois-Pichat 80.3 1978 1980 Iceland
United Nations 80.0 1979 1976 Iceland
Siegel 79.4 1980 1976 Iceland
Frejka 77.5 1981 1972 Sweden
World Bank 82.5 1984 1993 Japan
United Nations 82.5 1985 1993 Japan
United Nations 87.5 1989
World Bank 90.0 1989
Fries 85.0* 1990 1985 Japan
Olshansky et al. 85.0* 1990 1996 Japan
Coale and Guo 84.9 1991
United Nations 92.5 1998
Olshansky et al. 88.0 2001

Supplemental Table 2. Level of male and female life expectancy at
birth [e(0)] in best-practice and second-best countries from 1840 to
2000. The simplified data in the second column were used to produce
Fig. 1, as well as supplementary fig. 5. The annual data in subsequent
columns were used to produce suppl. table 1 and supplementary figs. 1
to 4, as well as the regression lines in Fig. 1 and 2. After 1948 the
simplified data are the same as the annual data. Before 1948 there are
gaps in the simplified data. The gaps arise for three reasons. First,
we omitted data for 1914-1919 (World War I and influenza) and
1939-1945 (World War II). Second, life tables that covered several
years of time, sometimes five or even ten years, were often published
before 1948. In the simplified data, we include the life expectancy
from such life tables only at the mid-year of the period covered. If
it appears that the country was the record holder for the entire
period, we do not include life expectancy values for other years in
the period. Third, there were sometimes gaps before 1948 between life
tables published for specific countries. If it appeared likely that a
country was the record-holder even in years when there was a gap in
the life tables for that country, then we do not include life
expectancy values during the gap in the simplified data. In contrast,
in the annual data the life expectancy published for a period of years
is assumed to hold for every year during that period: this is what
produces the horizontal patterns in supplementary figs. 1 to 4.
Furthermore, the record-holder in a year is chosen from among the
countries that have published life expectancy estimates for that year:
countries that did not publish estimates for that year are not
considered. It is reassuring that the linear trend in life expectancy
is not affected by the use of simplified vs. annual data and that a
linear trend holds for males as well as females and for the
second-best country as well as the best-practice country. The slope of
the regression line for best-practice female life expectancy is 0.243
regardless of whether the simplified or annual data are used and r2 is
0.992 for the simplified data and 0.982 for the annual data.

Year
then
Simplified data/ Female e(0)/ Country
then
Annual data / Female/ 2nd e(0)/ Country
then
Annual data/ Male/ e(0)/ Country/ 2nd e(0)

1840 45.71 Sweden 45.71 Swe 45.20 43.11 Denmark 43.00
1841 47.90 Norway 46.92 44.50 Nor 43.87
1842 47.90 Nor 46.49 44.50 Nor 44.21
1843 47.90 Nor 47.90 Nor 47.15 45.30 Den 44.50
1844 47.90 Nor 47.01 45.03 Den 44.50
1845 48.69 Swe 47.90 44.50 Nor 43.45
1846 49.56 Nor 45.20 46.43 Nor 43.00
1847 45.95 Nor 45.20 43.40 Nor 43.00
1848 48.64 Nor 47.09 Swe 46.54 43.26 Nor 43.00
1849 49.75 Nor 47.12 46.32 Nor 43.00
1850 51.14 Nor 51.14 47.70 Nor 47.70
1851 51.37 Nor 47.49 47.94 Nor 44.85
1852 49.75 Nor 45.20 46.89 Nor 43.00
1853* 51.19 Nor 49.21 Nor 45.20 46.44 Nor 43.00
1854 53.20 Nor 47.99 49.92 Nor 45.68
1855 52.12 Nor 47.38 48.53 Nor 45.38
1856 51.67 Nor 47.30 48.71 Nor 44.00
1857 51.46 Nor 47.30 48.70 Nor 44.00
1858 51.73 Nor 52.94 Nor 47.30 49.93 Nor 44.00
1859 51.16 Nor 47.30 48.47 Nor 44.00
1860 51.13 Nor 50.29 48.52 Nor 47.09
1861 49.70 Australia 48.70 47.09 Aust 46.41
1862 49.70 Austr 48.40 47.09 Aust 46.62
1863 49.70 Aust 49.70 Aust 48.07 47.09 Aust 45.22
1864 49.84 NoNZr 49.70 47.52 Nor 47.09
1865 51.71 Nor 49.70 48.87 Nor 47.09
1866 51.38 Nor 49.70 48.27 Nor 47.09
1867 49.70 Australia 49.44 47.09 Aust 46.10
1868 50.65 Nor 49.70 Aust 48.82 47.09 Aust 45.32
1869 50.88 Nor 49.70 47.46 Nor 47.09
1870 52.47 Nor 50.89 49.60 Ireland 49.16
1871 51.31 Nor 50.94 49.60 Ireland 47.93
1872 52.12 Swe 51.47 49.60 Ireland 48.43
1873 50.45 Nor 51.06 Nor 50.44 48.16 Nor 47.09
1874 49.70 Australia 49.18 47.09 Aust 46.31NZ
1875 49.70 Australia 49.19 47.09 Aust 46.13
1876 54.22 NZ 54.22 NZ 48.33 51.99 NZ 45.57
1877 51.21 Nor 48.39 48.32 Nor 46.52
1878 53.17 Nor 48.04 50.41 Nor 45.87
1879 54.39 Nor 50.32 52.00 Nor 47.45
1880 57.26 NZ 53.25 54.44 NZ 50.48
1881 57.26 NZ 56.32 54.44 NZ 52.75
1882 57.26 NZ 50.84 54.44 NZ 47.20
1883 57.26 NZ 50.84 54.44 NZ 48.50
1884 57.26 NZ 52.03 54.44 NZ 49.54
1885 57.26 NZ 52.30 54.44 NZ 49.76
1886 57.26 NZ 57.26 NZ 52.87 54.44 NZ 50.48
1887 57.26 NZ 52.98 54.44 NZ 50.57
1888 57.26 NZ 53.57 54.44 NZ 51.03
1889 57.26 NZ 53.35 54.44 NZ 51.09
1890 57.26 NZ 51.77 54.44 NZ 49.12
1891 58.09 NZ 57.26 55.29 NZ 54.44
1892 58.09 NZ 57.26 55.29 NZ 54.44
1893 58.09 NZ 58.09 NZ 54.76 55.29 NZ 51.06
1894 58.09 NZ 54.76 55.29 NZ 51.06
1895 58.09 NZ 55.47 55.29 NZ 52.89
1896 59.95 NZ 55.89 57.37 NZ 52.22
1897 59.95 NZ 55.67 57.37 NZ 52.84
1898 59.95 NZ 59.95 NZ 56.15 57.37 NZ 53.21
1899 59.95 NZ 54.76 57.37 NZ 51.06
1900 59.95 NZ 55.14 57.37 NZ 51.79
1901 60.55 NZ 58.84 58.09 NZ 55.20
1902 60.55 NZ 58.84 58.09 NZ 55.20
1903 60.55 NZ 60.55 NZ 58.84 58.09 NZ 55.20
1904 60.55 NZ 58.84 58.09 NZ 55.20
1905 60.55 NZ 58.84 58.09 NZ 55.20
1906 61.76 NZ 58.84 59.17 NZ 55.64
1907 61.76 NZ 58.84 59.17 NZ 55.75
1908 61.76 NZ 61.76 NZ 58.84 59.17 NZ 55.24
1909 61.76 NZ 59.57 59.17 NZ 57.22
1910 61.76 NZ 59.47 59.17 NZ 56.47
1911 63.48 NZ 61.11 60.96 NZ 57.35
1912 63.48 NZ 59.78 60.96 NZ 57.13
1913 63.48 NZ 63.48 NZ 60.08 60.96 NZ 57.26
1914 63.48 NZ 59.91 60.96 NZ 57.00
1915 63.48 NZ 59.78 60.96 NZ 56.39
1916 59.27 Swe 59.09 57.09 Swe 55.83
1917 60.09 Swe 59.35 57.63 Swe 56.12
1918 58.10 Den 58.00 55.80 Den 55.74
1919 58.25 Den 58.10 56.69 Den 55.80
1920 63.31 Australia 60.60 59.15 Aust 59.06
1921 65.93 NZDagger Symbol 63.31
62.58 NZDagger Symbol 60.30
1922 65.43 NZ 65.56 NZ 63.31 63.07 NZ 60.30
1923 65.14 NZ 63.87 62.59 NZ 61.81
1924 67.02 NZ 63.51 63.76 NZ 62.19
1925 66.72 NZ 65.11 64.07 NZ 62.26
1926 66.57 NZ 66.27 NZ 64.47 63.38 NZ 62.23
1927 66.96 NZ 64.32 64.03 NZ 61.82
1928 66.79 NZ 64.63 64.11 NZ 62.87
1929 66.95 NZ 63.83 63.69 NZ 61.38
1930 67.47 NZ 66.59 64.32 NZ 63.89
1931 67.88 NZ 67.90 NZ 65.60 65.05 NZ 63.60
1932 68.40 NZ 67.14 66.28 NZ 64.70
1933 69.25 NZ 67.14 66.20 NZ 65.36
1934 68.54 NZ 67.66 65.83 Netherllands 65.60
1935 69.25 NZ 67.24 66.34 NZ 65.74
1936 68.45 NZ 68.56 NZ 67.40 66.05 Neth 65.75
1937 68.51 NZ 67.70 66.19 Neth 65.87
1938 68.94 Nor 68.94 Nor 68.22 66.50 Neth 65.19
1939 69.02 NZ 69.00 66.90 Neth 65.76
1940 69.59 NZ 68.57 66.15 NZ 65.35
1941 70.30 Iceland 69.15 66.10 Iceland 65.86
1942 70.49 Swe 70.30 67.56 Swe 66.34
1943 70.30 Iceland 70.23 67.32 Swe 66.12
1944 70.30 Iceland 70.00 66.58 NZ 66.16
1945 70.37 Nor 70.30 67.13 Swe 66.78
1946 71.28 Nor 71.28 Nor 70.65 68.34 Swe 67.84
1947 71.70 NZ 71.63 68.32 Nor 68.31
1948 72.80 Nor 72.80 Nor 72.39 69.71 Neth 69.38
1949 73.03 Nor 73.03 Nor 72.36 69.96 Nor 69.44
1950 73.21 Nor 73.21 Nor 72.59 70.29 Neth 69.91
1951 75.00 Iceland 75.00 Iceland 74.22 70.75 Nor 70.70
1952 75.00 Iceland 75.00 Iceland 74.28 71.03 Nor 70.94
1953 75.02 Iceland 75.02 Nor 75.00 71.23 Nor 70.70
1954 75.05 Iceland 75.05 Nor 75.00 71.34 Nor 70.95
1955 75.28 Nor 75.28 Nor 75.00 71.56 Nor 71.05
1956 75.47 Nor 75.47 Nor 75.00 71.46 Nor 70.95
1957 75.48 Nor 75.48 Nor 75.00 71.59 Neth 71.36
1958 75.48 Nor 75.48 Nor 75.00 71.52 Swe 71.45
1959 75.74 Nor 75.74 Nor 75.17 71.56 Swe 71.36
1960 75.83 Nor 75.83 Nor 75.30 71.39 Neth 71.32
1961 76.20 Iceland 76.20 Iceland 76.02 71.64 Swe 71.43
1962 76.20 Iceland 76.20 Iceland 76.02 71.36 Swe 70.96
1963 76.20 Iceland 76.20 Iceland 75.76 71.53 Swe 71.00
1964 76.28 Neth 76.28 Neth 76.20 71.61 Swe 71.28
1965 76.49 Nor 76.49 Nor 76.20 71.70 Swe 71.13
1966 76.69 Nor 76.69 Nor 76.46 71.82 Swe 71.42
1967 76.95 Nor 76.95 Nor 76.59 71.83 Swe 71.33
1968 76.80 Nor 76.80 Nor 76.45 71.73 Swe 71.23
1969 76.67 Nor 76.67 Nor 76.61 71.73 Swe 70.90
1970 77.32 Nor 77.32 Nor 77.20 72.25 Swe 71.60
1971 77.40 Swe 77.40 Swe 77.36 72.00 Greece 71.97
1972 77.54 Swe 77.54 Swe 77.51 72.24 Iceland 72.03
1973 77.72 Swe 77.72 Swe 77.69 72.19 Greece 72.18
1974 78.26 Iceland 78.26 Iceland 77.96 72.53 Greece 72.22
1975 78.97 Iceland 78.97 Iceland 78.22 72.37 Iceland 72.23
1976 80.15 Iceland 80.15 Iceland 78.35 74.07 Iceland 72.36
1977 79.81 Iceland 79.81 Iceland 78.94 73.52 Iceland 72.60
1978 80.02 Iceland 80.02 Iceland 78.90 73.88 Iceland 72.96
1979 79.73 Iceland 79.73 Iceland 79.06 74.25 Iceland 73.30
1980 80.55 Iceland 80.55 Iceland 79.22 73.59 Iceland 73.40
1981 79.91 Iceland 79.91 Iceland 79.38 73.80 Japan 73.38
1982 79.78 Iceland 79.78 Iceland 79.71 74.76 Iceland 74.20
1983 80.64 Iceland 80.64 Iceland 79.80 74.20 Japan 73.63
1984 80.57 Iceland 80.57 Iceland 80.35 74.91 Iceland 74.50
1985 80.50 Switzerland 80.50 Switz 80.40 75.11 Iceland 74.80
1986 80.90 Japan 80.90 Japan 80.74 75.43 Iceland 75.20
1987 81.40 Japan 81.40 Japan 81.06 75.60 Japan 74.99
1988 81.30 Japan 81.30 Japan 81.11 75.50 Japan 74.53
1989 81.70 Japan 81.70 Japan 81.30 76.23 Iceland 75.90
1990 81.80 Japan 81.80 Japan 81.02 75.90 Japan 75.62
1991 82.11 Japan 82.11 Japan 81.45 76.11 Japan 74.91
1992 82.22 Japan 82.22 Japan 81.71 76.85 Iceland 76.09
1993 82.51 Japan 82.51 Japan 81.77 77.19 Iceland 76.25
1994 82.98 Japan 82.98 Japan 82.11 77.15 Iceland 76.57
1995 83.26 Japan 83.26 Japan 81.80 76.72 Japan 76.40
1996 83.60 Japan 83.60 Japan 82.00 77.00 Japan 76.90
1997 83.80 Japan 83.80 Japan 82.30 77.20 Japan 76.60
1998 84.00 Japan 84.00 Japan 82.50 77.90 Iceland 77.20
1999 83.90 Japan 83.90 Japan 82.50 77.80 Iceland 77.40
2000 84.62 Japan 84.62 Japan 77.64 Japan

*In 1853 and in some subsequent years, the life expectancy given in
the simplified data differs from that for the same country given in
the annual data. The simplified data are sometimes based on life
tables that pertain to a period of several years, usually five or ten
years, whereas the annual data are based on calculations for the
specific year.

Dagger SymbolData for New Zealand pertain to the non-Maori population.
Data for the Maori population are of very poor quality until 1926.
From 1926 to the present the quality of the data has gradually
improved but there are still serious problems of age misreporting at
older ages. See Ian Pool, Te Iwi Maori: A New Zealand Population:
Past, Present and Projeced (Auckland Univ. Press, Auckland, 1991); I.
Pool, N. Z. Pop. Rev. 8, 2 (1982); V. Kannisto, The Advancing Frontier
of Survival (Odense Univ. Press, Odense, 1996), p. 17. From 1921
through 1955 the annual data in supplementary table 2 are derived from
S. K. Jain, Source Book of Population Data: New Zealand, Non-Maori
Population 1921-1967, Vols. 1-3 (Research School of Social Sciences,
Australian National Univ., Canberra, 1972). Because Jain's life tables
end with the interval 75+, he based his life-expectancy calculations
on an estimate of the life years lived above age 75, L75+. Jain used
an approximation that consistently underestimates life expectancy at
birth compared with the official life tables for New Zealand. We
estimated life expectancy from Jain's data by using the approximation
L75+ = l75/m75+ , where l75 is the life-table probability of survival
to age 75 and m75+ is the central death rate above age 75. Our
estimates are consistent with the official estimates over the period
from 1921 through 1955.