Castration may be the key.
While it sounds a little extreme, new University of Otago research shows blocking reproduction can increase the lifespan of males and females of 117 different species.
Using data from mammals housed in zoos and aquariums worldwide, the researchers found ongoing hormonal contraception and permanent surgical sterilisation were associated with increased life expectancy.
Lead author and University of Otago School of Biomedical Sciences researcher Associate Prof Mike Garratt said the relative increase in lifespan was similar across the sexes, but the cause might be different in males and females.
"In males, only castration extends lifespan — not vasectomy — which indicates that the effect comes from removing sex hormones.
"These hormones may interact with pathways that regulate the biology of ageing, particularly during early-life development, since early-life castration has the strongest effects on lifespan."
The health of laboratory rodents later in life was also increased by castration.
In females, lifespan increased after several different forms of sterilisation.
"It suggests that benefits arise from reducing the substantial energetic and physiological costs of pregnancy, lactation and caring for offspring, rather than from a single hormonal mechanism," Assoc Prof Garratt said.
"However, while lifespan was increased by a range of sterilisation approaches, in the case of ovary removal, which also removes ovarian hormone production, aspects of health in later life are impaired.
"These findings on lifespan and healthspan shed light on the health-survival paradox observed in post-menopausal women, who outlive men on average, but suffer increased frailty and poorer overall health during ageing."
The study also included a meta-analysis of other vertebrate sterilisation studies, and the researchers found life expectancy increased by 10% to 20%, depending on the timing of treatment and the environment the animal was exposed to.
