Grandmotherhood across the demographic transition

• Published in: PloS one Vol. 13; no. 7; p. e0200963
• Main Authors: Chapman, Simon N, Pettay, Jenni E, Lahdenperä, Mirkka, Lummaa, Virpi
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 23-07-2018; Public Library of Science (PLoS)
• Subjects: 19th century; 20th century; Age; Age Factors; Aged; Analysis; Biological evolution; Biology; Biology and Life Sciences; Child; Child development; Childhood; Children; Cohort analysis; Cultural heritage; Demographic transition theory; Demographics; Demography; Determinants; Evaluation; Evolution; Families & family life; Family Relations; Female; Fertility; Genealogy; Grandmothers; Grandparent-child relations; Grandparents; Human populations; Humans; Intergenerational relationships; Internet; Longevity; Medicine and Health Sciences; Menopause; Mental health; Mortality; Mortality rates; People and places; Population; Population Dynamics; Research and Analysis Methods; Social aspects; Social Sciences; Sociology; Survival analysis; Trends; United States; Finland
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0200963

Grandmothers provide key care to their grandchildren in both contemporary and historic human populations. The length of the grandmother-grandchild relationship provides a basis for such interactions, but its variation and determinants have rarely been studied in different contexts, despite changes in age-specific mortality and fertility rates likely having affected grandmotherhood patterns across the demographic transition. Understanding how often and long grandmothers have been available for their grandchildren in different conditions may help explain the large differences between grandmaternal effects found in different societies, and is vital for developing theories concerning the evolution of menopause, post-reproductive longevity, and family living. Using an extensive genealogical dataset from Finland spanning the demographic transition, we quantify the length of grandmotherhood and its determinants from 1790-1959. We found that shared time between grandmothers and grandchildren was consistently low before the demographic transition, only increasing greatly during the 20th century. Whilst reduced childhood mortality and increasing adult longevity had a role in this change, grandmaternal age at birth remained consistent across the study period. Our findings further understanding of the temporal context of grandmother-grandchild relationships, and emphasise the need to consider the demography of grandmotherhood in a number of disciplines, including biology (e.g. evolution of the family), sociology (e.g. changing family structures), population health (e.g. changing age structures), and economics (e.g. workforce retention).