A1 Refereed original research article in a scientific journal
Grandmother presence improved grandchild survival against childhood infections but not vaccination coverage in historical Finns
Authors: Ukonaho Susanna, Chapman Simon N, Briga Michael, Lummaa Virpi
Publisher: ROYAL SOC
Publication year: 2023
Journal: Proceedings of the Royal Society B: Biological Sciences
Journal name in source: PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
Journal acronym: P ROY SOC B-BIOL SCI
Article number: 20230690
Volume: 290
Number of pages: 9
ISSN: 0962-8452
eISSN: 1471-2954
DOI: https://doi.org/10.1098/rspb.2023.0690
Web address : https://doi.org/10.1098/rspb.2023.0690
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/180212535
Grandmother presence can improve the number and survival of their grandchildren, but what grandmothers protect against and how they achieve it remains poorly known. Before modern medical care, infections were leading causes of childhood mortality, alleviated from the nineteenth century onwards by vaccinations, among other things. Here, we combine two individual-based datasets on the genealogy, cause-specific mortality and vaccination status of eighteenth- and nineteenth-century Finns to investigate two questions. First, we tested whether there were cause-specific benefits of grandmother presence on grandchild survival from highly lethal infections (smallpox, measles, pulmonary and diarrhoeal infections) and/or accidents. We show that grandmothers decreased all-cause mortality, an effect which was mediated through smallpox, pulmonary and diarrhoeal infections, but not via measles or accidents. Second, since grandmothers have been suggested to increase vaccination coverage, we tested whether the grandmother effect on smallpox survival was mediated through increased or earlier vaccination, but we found no evidence for such effects. Our findings that the beneficial effects of grandmothers are in part driven by increased survival from some (but not all) childhood infections, and are not mediated via vaccination, have implications for public health, societal development and human life-history evolution.
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