society Nature Is Weird

The age when women stop being fertile and the age when they die have been moving back in perfect sync for decades.

April 14, 2026

Original Paper

Parallel Ageing: The Synchronised Postponement of Fertility and Mortality

Serena Vigezzi, Annette Baudisch

SocArXiv · b7shw_v2

The Takeaway

For the last 35 years, both fertility and mortality limits have shifted at the exact same pace. This suggests there is a deep, singular biological clock that controls both our ability to have children and our ultimate expiration date.

From the abstract

As births and deaths occur at progressively older ages, further delays must increasingly encounter resistance from existing physiological constraints. For female fertility, these constraints ultimately manifest as menopause. Whether an analogous limit exists for survival, however, remains debated. Evidence indicates that reproductive and actuarial ageing share underlying physiological constraints. We hypothesize that these common constraints limit fertility and mortality postponement in similar