Can hormones explain why women live longer than men on average?
Hormones likely contribute to women's survival advantage, but do not fully explain it. If you want to better understand your own risk profile, lifestyle and hereditary factors are at least equally relevant to explore.
Women live longer than men in almost all circumstances, yet there is no single all-explaining cause. Hormones, sex chromosomes and mitochondrial inheritance are all discussed as possible mechanisms. None of them individually has strong, irrefutable evidence behind it yet.
The clearest hormonal signal comes from the ovaries in women and from the testes in men. Historical data on men who were castrated before puberty show that they lived considerably longer than non-castrated men. The same pattern is seen in castrated male mammals in controlled environments. This suggests that androgens (male sex hormones) shorten lifespan. In women the picture is reversed: when the ovaries are surgically removed, survival declines slightly. That suggests that oestrogen still does something protective even after the reproductive years.
Oestrogen protects the heart and blood vessels, at least before menopause. Young women have a lower risk of heart disease than men of a comparable age. After menopause that advantage disappears. Oestrogen also influences systems that regulate blood pressure. This mechanism is plausible, but it has not yet been proven to explain the full longevity gap.
At the same time, the picture is not purely rosy for women. Hormonal fluctuations across the lifespan increase the risk of sleep disorders in women. After menopause, the altered hormonal profile can also increase vulnerability to oxidative stress and possibly neurodegenerative conditions such as Alzheimer's disease. And although women live longer, they spend those extra years in illness and with limitations more often than men do. A longer lifespan therefore does not automatically mean more healthy years.
Beyond hormones, reproduction itself also plays a role. In both males and females of various mammal species, sterilisation is associated with a longer lifespan. This suggests that the reproductive process itself costs energy and causes damage. Telomeres, the protective ends of chromosomes, are on average shorter in men than in women, which may contribute, but this pattern is not universal across animal species and it is unclear whether this is a cause or a consequence.
The claims are based on a mix of associational human research, animal studies and mechanistic studies. No large randomised trials are available for this question. Causality is plausible but not proven for most mechanisms.