Live fast, die young, leave a good-looking offspring: longevity and reproduction trade-offs in rural Spain (1536–1965)

One of the most debated evolutionary theories is the trade-off between fertility and longevity. Specifically, women who experience more childbirths may have a shorter lifespan due to reduced opportunities for their bodies to recover from the associated costs. Previous studies have produced varied results, largely due to the challenge of distinguishing evolutionary factors from genetic and environmental influences in human societies. Since both longevity and fertility patterns tend to be inherited across generations, long-term historical longitudinal population samples are particularly valuable for exploring this trade-off, as they not only provide large population samples across different temporal contexts but also allow for the control of intergenerational transmission of behavior. In this study, we use a sample of 5097 women from rural Spain (based on parish records from 17 villages) who died between the sixteenth and twenty-first centuries to investigate whether a trade-off between fertility and longevity has existed. In all cases, we can control for the experiences of their parents. Our findings reveal a substantial negative impact of parity on women's longevity, as well as the adverse effect of having an early birth before fertility control was established. Additionally, we observed a significant negative effect of a prolonged reproductive cycle on natural fertility.