The Effect of Fertility on the Evolution of the Post-Reproductive Sex Ratio

Giambattista Salinari , Università degli Studi di Sassari
Cristina Giuliani, University of Bologna
Marco Breschi, Università degli Studi di Sassari
Virginia Zarulli, University of Southern Denmark - Interdisciplinary Center on Population Dynamics
Claudio Franceschi, University of Bologna
Gustavo De Santis, University of Florence

At post-reproductive ages (50+), there are typically fewer men than women, whose mortality is lower. This is generally imputed to genes (sex hormones, sex chromosomes and the mitochondrial DNA) and smoking. In this paper, however, we submit and test an alternative hypothesis: high fertility was one of the causes of high female mortality in the post reproductive age span (50 years and over) of past generations, and extra improvements in female survival, as compared to men, could be observed only after, and because of, the fertility transition. To substantiate our claim, we analyze longitudinal (aggregate) data of the cohorts born between the end of the 19th and mid-20th century in 16 Italian regions and 16 European countries: the effects of differential cohort fertility on female survival are evident and become stronger with age. This is in line with some theories of evolutionary medicine, which suggest that increased somatic investment in the reproductive function among women comes at the cost of worse health and lower survival in the post-reproductive period.

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 Presented in Session P1. Poster Session Fertility, Family and the Life Course