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Updated: Jul 10, 2026

Measurement of Lifespan in Drosophila melanogaster
Published on: January 7, 2013
Mortality-rate crossovers and maximum lifespan in advantaged and disadvantaged populations: accelerated-mortality and
H R Hirsch1, X Liu, T M Witten
1Department of Physiology, University of Kentucky, Lexington, KY 40536-0298, USA.
Abstract:
One population is advantaged relative to another by our definition if its survival function is greater at all ages. A population has a lifespan maximum if there is an age at which its survival function becomes exactly zero. Earlier work concerned conditions under which the mortality-rate functions of advantaged and disadvantaged populations displaying lifespan maxima always crossed. Here two survival models of populations having lifespan maxima are presented in which mortality-rate crossings between advantaged and disadvantaged subpopulations may fail to appear. One, the accelerated-mortality model, has a continuous survival function; in the other, the sudden-death model, the survival function is discontinuous. Both differ from examples examined previously in that their mortality-rate functions become infinite at their lifespan maxima.
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