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On generating birth rates from skeletal populations
Author(s) -
Horowitz Sheryl,
Armelagos George,
Wachter Ken
Publication year - 1988
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330760207
Subject(s) - life expectancy , population , demography , birth rate , birth–death process , mortality rate , fertility , demographic analysis , statistics , mathematics , sociology
Sattenspiel and Harpending (1983, American Antiquity 48(3): 489–498) have stated that the life expectancy at birth ( e 0 0 ) which paleodemographers calculate from skeletal population data is actually the mean age at death (ā d ) of the population. Yet, only when a population is neither growing or declining (i.e., is stationary) are these two statistics equivalent. They further assert, that the mean age at the death (ā d ) is more accurately interpreted as a measure of the fertility of the population. While we support their statement that since paleodemographic calculations use skeletal evidence of death, these do not a priori produce life expectancy values, we disagree that the inverse of the birth rate is a substitute for the average age at death (ā d ). The following pages demonstrate that: 1) An exact expression for the relationship between ā d and 1/ b can be derived using standard stable population theory, wherein ā d = 1/ b is shown to be a special case. 2) There are only two cases when ā d = 1/ b is an identity. 3) Whereas empirically ā d and 1/ b appear to correspond closely, this is an artifact of heavy mortality at early ages, which is a characteristic of the populations being considered. 4) Without insights into the behavioral dynamics of the situation any assessment of the demographics of the population is questionable.