Cutting time short or long? Castration, developmental timing, and longevity in imperial China

BACKGROUND: Life-history theory predicts a trade-off between reproduction and longevity. Castration has been proposed to extend male lifespan by reducing androgen-related costs, but evidence from human populations remains limited. AIM: This study examined whether eunuchs in imperial China had a survival advantage over comparable non-castrated men and whether earlier-life castration was associated with greater longevity. SUBJECTS AND METHODS: Biographical records of eunuchs and non-castrated bureaucrats from the Tang (618-907 CE) and Ming (1368-1644 CE) dynasties were analysed. Hypothesis 1 compared age at death between eunuchs and bureaucrats within each dynasty using bootstrapped regression models controlling for birth year. Hypothesis 2 analysed a subset of 160 Ming eunuchs with age at court entry, using both linear regression and puberty-threshold models, with age at court entry used as a proxy for age at castration. Earlier court entry did not predict greater longevity in either the linear regression or puberty-threshold models. CONCLUSION: The survival effects of castration in humans appeared modest and context-dependent rather than uniformly beneficial and were shaped by broader biosocial and mortality conditions.