Key points from article :
A large new study led by Mike Garratt at the University of Otago shows that animals tend to live longer when reproduction is blocked, supporting a long-standing idea in biology that reproduction comes at a cost to bodily maintenance. Published in the journal Nature, the research analyzed data from zoos and aquariums worldwide, covering 117 mammal species, and found that preventing reproduction was linked to a 10–20% increase in lifespan in both males and females.
The researchers found that the reasons for this longevity boost differ between the sexes. In males, only castration—not vasectomy—extended lifespan, pointing to the role of sex hormones in accelerating aging and risky behaviors such as aggression. Early-life removal of these hormones had the strongest effect, suggesting they shape aging pathways from a young age. In females, longer life was seen across several methods of preventing reproduction, indicating that the benefit comes mainly from avoiding the heavy energy demands of pregnancy, lactation, and caring for offspring rather than from a single hormonal pathway.
The study also sheds light on how reproduction affects health later in life. Males that did not reproduce were less likely to die from injuries linked to risk-taking, while females showed fewer deaths from infections, consistent with the immune strain associated with reproduction. However, the researchers caution that longer life does not always mean better health: some methods, such as ovary removal, extended lifespan but worsened late-life health. Together, the findings help explain phenomena like menopause and highlight the complex trade-offs between reproduction, lifespan, and health across mammals.
