Costs of reproduction and ageing in the human female

Abstract

Evolutionary theories of ageing point to reproduction as a significant factor to consider when asking why ageing occurs and why there is inter-individual variation in its progression. Reproduction in human females is costly, in terms of energy, nutrients and metabolic adjustments. Thus, it is expected that women who experienced high reproductive effort resulting from multiple reproductive events will age faster. However, the evidence for long-term negative effects of reproduction is not conclusive. The lack of understanding of whether there are trade-offs between reproduction and ageing in women is partly due to methodological challenges. The costs of reproduction are often calculated based only on parity, while other elements contributing to these costs (e.g. breastfeeding, timing of reproduction) are neglected, which may significantly underestimate the total costs and obscure the all-important inter-individual variation in such costs. Costs must be evaluated in relation to individual characteristics, including developmental conditions, nutritional status and social support that a mother receives during reproduction. Furthermore, ageing and health must be assessed based on comprehensive markers rather than arbitrarily assembled variables. Finally, longitudinal rather than cross-sectional studies and new statistical approaches are needed to reveal how much of a decline in health and progressing ageing can actually be attributed to past reproductive processes. This article is part of the theme issue ‘Evolution of the primate ageing process'.

Inflammaging: Blame the sons. Relationships between the number of sons and the level of inflammatory mediators among post‐reproductive women

“…Overall, these findings suggest that women's reproductive history should be considered as an important factor influencing post-reproductive health and aging. Of course, there are other traits related to women's reproductive history that could explain variations in health status among older women (for review, see: Jasienska, 2009Jasienska, , 2020. Even the relationship between the number of sons and inflammaging could potentially be influenced by the timing of reproduction (very early or very late reproduction may be more risky for mothers [Laopaiboon et al, 2014;Tomassini et al, 2018]), birth sequence (sons born in succession or as twins could be more challenging for the maternal organism [Grundy & Tomassini, 2005;Jelenkovic et al, 2014]) or length of interbirth intervals (shorter intervals result in less time for maternal maintenance and repair [Ellison, 2001;Mace & Sear, 1997;Schummers et al, 2018]).…”

Productivity loss associated with functional disability in a contemporary small-scale subsistence population

“…reliance on hunted versus other foods). Fertility patterns are not explicitly considered in the present study, but they can influence both somatic condition, particularly for women ( Jasienska, 2020 ; Ryan et al, 2018 ; Stieglitz et al, 2015a ; Stieglitz et al, 2019 ; Ziomkiewicz et al, 2016 ), and economic productivity ( Hooper et al, 2015 ; Kramer, 2005 ). Extensive longevity may be a novel life history feature of modern H. sapiens that was absent among prior hominin species; extant hunter-gatherers with relatively minimal acculturation exhibit a modal adult lifespan of 68–78 years ( Gurven and Kaplan, 2007 ).…”

Insights from evolutionarily relevant models for human ageing

“…Is this the biological reality or a product of methodological limitations? In this volume, Jasienska [104] advocates for evolutionarily informed approaches to design more powerful studies of the health effects of reproduction, including more realistic assessments of reproductive effort. However, using detailed measures of reproductive effort, Phillips et al [92] found that wild chimpanzee females experienced only transient increases in faecal parasites during pregnancy, and high fertility predicted lower, not higher parasitism with age.…”

“…Is this the biological reality or a product of methodological limitations? In this volume, Jasienska [104] advocates for evolutionarily informed approaches to design more powerful studies of the health effects of reproduction, including more realistic assessments of reproductive effort. However, using detailed measures of reproductive effort, Phillips et al .…”