In a Stationary Population, the Average Lifespan of the Living Is a Length-Biased Life Expectancy

What is the average lifespan in a stationary population viewed at a single moment in time? Even though periods and cohorts are identical in a stationary population, we show that the answer to this question is not life expectancy but a length-biased version of life expectancy. That is, the distribution of lifespans of the people alive at a single moment is a self-weighted distribution of cohort lifespans, such that longer lifespans have proportionally greater representation. One implication is that if death rates are unchanging, the average lifespan of the current population always exceeds period life expectancy. This result connects stationary population lifespan measures to a well-developed body of statistical results; provides new intuition for established demographic results; generates new insights into the relationship between periods, cohorts, and prevalent cohorts; and offers a framework for thinking about mortality selection more broadly than the concept of demographic frailty.

Population genetics of transposable element load: a mechanistic account of observed overdispersion

In an empirical analysis of transposable element (TE) abundance within natural populations of Mimulus guttatus and Drosophila melanogaster, we found a surprisingly high variance of TE count (e.g., variance-to-mean ratio on the order of 10 to 100). To obtain insight regarding those evolutionary genetic mechanisms that are may underlie the overdispersed population distributions of TE abundance, we developed a mathematical model of TE population genetics that includes the dynamics of element proliferation and purifying selection on TE load. The modeling approach begins with a master equation for a birth-death process and it extends the predictions of the classical theory of TE dynamics in several ways. In particular, moment-based analysis of stationary population distributions of TE load reveal that overdispersion is most likely to arise via copy-and-paste (as opposed to cut-and-paste) dynamics. Parameter studies suggest that overdispersed population distributions of TE abundance are probably not a consequence of purifying selection on total element load.

Stationary population, immigration, social cohesion, and national identity: What are the links and the policy implications? With special attention to Canada: A demographer’s point of view

In recent years, this author has devoted some of his research to the question of stationary population as a policy vision for Canada and beyond. The focus was largely economics and ecology. The virtue of the stationary population, it was argued, is that it cut across ecologists’ long-term concerns and economists’ short-term concerns. The present paper, while reiterating some of the same economic arguments, addresses stationary population as a policy option from the point of view of national identity and social cohesion. To this end, it explores the policy and ideological dimensions of multiculturalism in Canada. It also examines immigration trends in Canada and Western Europe, and makes some incursions into the history of how cosmopolitan states have fared. The paper’s conclusion is that stationary population is optimal in terms of national identity and social cohesion. Ces dernières années, l’auteur a consacré certaines de ses recherches à la question de la population stationnaire au Canada et ailleurs dans le monde. L’optique en a été économique et écologique. La vertu de la population stationnaire, il a été soutenu, réside dans le fait qu’elle réponde aux préoccupations tant à long terme des écologistes qu’à court terme des économistes. Tout en réitérant ces préoccupations, la présente étude examine les attributs de la population stationnaires du point de vue de l’identité nationale et de la cohésion sociale. Dans ce but, l’étude explore les dimensions du multiculturalisme au Canada. Sont également examinés les courants migratoires au Canada et dans les pays occidentaux, tout en faisant des incursions dans l’histoire des sociétés cosmopolites, leurs réussites et leurs échecs. La conclusion de la présente étude est que la population stationnaire est optimale des points de vue de l’identité nationale et de la cohésion sociale.

Canada: The case for stable population with moderately low fertility and modest immigration

Commentary on Anatole Romaniuk (2017), Stationary Population, Immigration, Social Cohesion and National Identity: What are the Links and the Policy Implications? With special attention to Canada. A Demographer’s point of view

Stationary population: Author’s reply to comments by reviewers

Forum: Opinion and perspectives on Canadian population policy