Human Life Expectancy – Two 18th Century Scientific Papers

Life
expectancy
is
a statistical measure of how long a person or organism may live,
based on the year of their birth, their current age and other
demographic factors including gender. At a given age, life expectancy
is the average number of years that is likely to be lived by a group
of individuals (of age
x
)
exposed to the same mortality conditions until they die…
Mathematically,
life expectancy is the mean number of years of life remaining at a
given age, assuming constant mortality rates.
.
.
Longevity
and
life expectancy are not synonyms. Life expectancy is defined
statistically as the average number of years remaining for an
individual or a group of people at a given age. Longevity refers to
the characteristics of the relatively long life span of some members
of a population. Moreover, because life expectancy is an average, a
particular person may well die many years before or many years after
their “expected” survival. The term “
maximum
life span
”
has a quite different meaning and is more related to longevity.
[Wikipedia]
T
he
methodology for determining life expectancy has evolved over the
years. The accuracy of the projections has a pronounced effect on
both the societal and economic interests of individuals and
governments.
The
two papers here describe some of the work done in the 18
th
century to evaluate and improve the estimates of life expectancy. The
two papers are:
A
View of the Relation between the celebrated Dr. Halley
’s
Tables, and the Notions of Mr. De Buffon, for establishing a Rule for
the probable Duration of the Life of Man; by Mr. William Kersseboom,
of the Hague. Translated from the French, by James Parsons, M. D, and
F. R. S.
London:
Philosophical Transactions, 1754. The preparation of statistical
tables to predict life expectancy was
performed
by competing analysts. In this paper, Mr. Kersseboom compares several
tables to determine why they differ from each other.
[
The
item is a First Edition, extracted and disbound from The
Philosophical Transactions of the Royal Society, Vol. 48, For the
Year 1753, pages 239-252. This volume of the transactions was
published in London in 1754.
]
A
Letter to the Rev. Dr. William Brakenridge, Rector of St. Michael
Bassishaw, London, and F.R.S. concerning the Term and Period of Human
Life: In which the Inequalities in constructing, and the false
Conclusions drawn from Dr. Halley’s Breslau Table are fully proved;
the supposed extraordinary Healthfulness of that Place is
particularly examined, and confuted; and its real State equaled by
divers Places in England; the Imperfection of all the Tables formed
upon 1000 Lives is shewn; and a Method proposed to obtain one much
better: By T. W., A.M.
London: Philosophical Transactions, 1763.
The ability to improve life expectancy tables as more data and more
recent information is considered is demonstrated in this paper.
[
The item is a First Edition, extracted and disbound from The
Philosophical Transactions of the Royal Society, Vol. 52, For the
Years 1761 & 1762, pages 46-70. This volume was published in
1763.
]
The
illustrations above show the first page of each paper.