Search for a resource-based trade-off between lifetime reproductive effort and women's postreproductive survival in preindustrial Sweden

Abstract

A reduced survival as a potential cost of high lifetime reproductive effort in women has intrigued human evolutionary biologists for more than a century. However, we do not currently have compelling evidence for the delayed survival costs of reproduction. Reasons for this may include several methodological issues, such as environmental confounding, measurement of individuals' lifetime reproductive effort using demographic data, and the practice of mortality selection that are all likely to compromise our ability to reliably detect trade-offs at the phenotypic level. The current research aims to address all these issues by using structural equation modeling to examine the potential trade-off between women's lifetime reproductive effort and their postreproductive mortality in a large data set of 6,594 women from preindustrial northern Sweden that has not previously been used for this purpose. Despite this, the results showed only weak evidence for a trade-off between lifetime reproductive effort and postreproductive mortality, one that was confined to only those women who had high lifetime reproductive effort and spend more than 25 years in widowhood. The socioeconomic status of the family or mother's ethnic background did not moderate this association, with the general trend being one of higher, not lower, postreproductive survival with high lifetime reproductive effort in women.