Reproductive suppression and longevity in human birth cohorts

Area of Science:

• Demography
• Evolutionary Biology
• Human Longevity

Background:

• Reproductive suppression, a phenomenon where pregnancies terminate due to perceived high mortality among young conspecifics, has implications for human health.
• Extending this concept to humans suggests populations exposed to such conditions should exhibit increased longevity.
• Previous research has not empirically tested this prediction in human populations.

Purpose of the Study:

• To investigate whether human birth cohorts exposed in utero to reproductive suppression exhibit altered lifespan.
• To test the hypothesis that environments with high child mortality lead to increased longevity in subsequent birth cohorts.

Main Methods:

• Utilized time-series analysis on Swedish vital statistics from 1751-1800.
• Assessed exposure to reproductive suppression by examining the odds of death among 1-9-year-old Swedes.
• Measured the impact on cohort life expectancy, employing methods to control for autocorrelation.

Main Results:

• Reproductive suppression was found to increase the lifespan of 24 annual birth cohorts by at least 1.3 years over the 50-year study period.
• Twelve of these cohorts experienced lifespan increases exceeding 1.7 years compared to expected longevity.
• Findings suggest a significant positive correlation between exposure to reproductive suppression and enhanced longevity.

Conclusions:

• Empirical evidence from Sweden supports the theory that human populations experiencing environments dangerous for children yield birth cohorts with unexpectedly greater longevity.
• The study provides the first empirical test of reproductive suppression's impact on human lifespan, indicating a survival benefit in historically high-mortality settings.