title: On the heterogeneity of human populations as reflected by mortality dynamics.
abstract: The heterogeneity of populations is used to explain the variability of mortality rates across the lifespan and their deviations from an exponential growth at young and very old ages. A mathematical model that combines the heterogeneity with the assumption that the mortality of each constituent subpopulation increases exponentially with age, has been shown to successfully reproduce the entire mortality pattern across the lifespan and its evolution over time. In this work we aim to show that the heterogeneity is not only a convenient consideration for fitting mortality data but is indeed the actual structure of the population as reflected by the mortality dynamics over age and time. In particular, we show that the model of heterogeneous population fits mortality data better than other commonly used mortality models. This was demonstrated using cohort data taken for the entire lifespan as well as for only old ages. Also, we show that the model can reproduce seemingly contradicting observations in late-life mortality dynamics. Finally, we show that the homogenisation of a population, observed by fitting the model to actual data of consecutive periods, can be associated with the evolution of allele frequencies if the heterogeneity is assumed to reflect the genetic variations within the population.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Demetris
authors.initials: D
authors.lastname: Avraam
authors.affiliation: Department of Actuarial Science, Faculty of Business and Economics (HEC Lausanne), University of Lausanne, Lausanne, Switzerland.
authors.forename: Séverine
authors.initials: S
authors.lastname: Arnold
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
authors.forename: Olga
authors.initials: O
authors.lastname: Vasieva
authors.affiliation: Department of Mathematical Sciences, University of Liverpool, Liverpool, UK.
authors.forename: Bakhtier
authors.initials: B
authors.lastname: Vasiev
mesh_terms: D000375:Aging / Q000502:physiology*; D018740:Genetic Heterogeneity; D006801:Humans; D008136:Longevity; D008962:Models, Theoretical; D009026:Mortality; D011157:Population Dynamics
keywords: demography; mathematical modeling; model fitting; mortality dynamics; population genetics