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M. Sánchez-Romero, D. Ediev, G. Feichtinger, A. Fürnkranz-Prskawetz:
"How many old people have ever lived?";
Demographic Research, 36 (2017), 54; S. 1667 - 1702.

BACKGROUND
Uninformed generalizations about how many elderly people have ever lived, based on a
poor understanding of demography, are found in a surprising number of important publications.
OBJECTIVE
We extend the methodology applied to the controversial question "how many people have
ever been born?" initiated by Fucks, Winkler, and Keyfitz, to the proportion of people
who have ever reached a certain age y and are alive today (denoted as π(y, T)).
METHODS
We first analyze the fraction π(y, T) by using demographic data based on UN estimates.
Second, we show the main mathematical properties of π(y, T) by age and over time.
Third, we complete our analysis by using alternative population models.
RESULTS
We estimate that the proportion who have ever been over 65 that are alive today (as of
2010) ranges between 5.5 and 9.5%. We extend the formal demographic literature by
considering the fraction of interest in two frequently referred models: the stable and
hyperbolic growth populations.
1 Wittgenstein Centre for Demography and Global Human Capital (IIASA,VID/OAW, WU). ¨
E-Mail: miguel.sanchez@oeaw.ac.at.
2 North Caucasian State Humanitarian Technological Academy (IAMIT), Lomonosov Moscow State University
(HSMSS/Demography Department), Wittgenstein Centre for Demography and Global Human Capital
(IIASA,VID/OAW, WU). E-Mail: ediev@iiasa.ac.at. ¨
3 Vienna University of Technology (TU Wien), Wittgenstein Centre for Demography and Global Human Capital
(IIASA,VID/OAW, WU). E-Mail: gustav.feichtinger@tuwien.ac.at. ¨
4 Vienna University of Technology (TU Wien), Wittgenstein Centre for Demography and Global Human Capital
(IIASA,VID/OAW, WU). E-Mail: afp@econ.tuwien.ac.at. ¨
http://www.demographic-research.org 1667
Sanchez-Romero et al. ´ : How many old people have ever lived?
CONCLUSIONS
We show that statements claiming half of all people who have ever reached the age of
65 are alive today ranges would never be attainable, neither theoretically nor empirically,
according to existing data.
CONTRIBUTION
We have produced for the first time a harmonized reconstruction of the human population
by age throughout history. For a given contemporaneous time T, we demonstrate analytically
and numerically that π(y, T) is nonmonotonic in age y. For a given age y, we show
that π(y, T) may also be nonmonotonic with respect to T.

people ever lived/elder/population ageing/formal demography

http://dx.doi.org/10.4054/DemRes.2017.36.54