Why Women Outlive Men, Sex Cells Explain Female Longevity

Most people think that women live longer than men do. Better stress management, healthier lifestyle choices, and biological variations are some of the explanations credited with this development. Women tend to live longer because they focus on their health and have greater social networks. But regardless of gender, life expectancy varies greatly among humans.

Biologists have hypothesised that reproductive variables may have a role in the gender disparity in life expectancy.

In a study published in Science Advances, researchers from Osaka University have discovered for the first time that germ cells, the cells that develop into eggs in females and sperm in males, drive sex-dependent lifespan differences in vertebrate animals.

The researchers examined ageing in the turquoise killifish, a small, fast-growing freshwater fish with a lifespan of only a few months. As in humans, female killifish live longer than males. However, when the researchers removed the germ cells from these fish, they found that males and females had similar lifespans.

"After removing the germ cells, male killifish lived longer than usual, and female lifespans became shorter," explains lead author Kota Abe. "We wanted to understand how germ cells could affect males and females so differently. Our next step was to investigate the factors responsible."

The study found that female killifish without germ cells had less oestrogen and more growth factor signalling, leading to health issues and accelerated ing. Conversely, male killifish showed improved health and increased vitamin D signaling. This suggests vitamin D may enhance longevity, prompting further testing with supplements.

"When we administered active vitamin D, we found that the lifespans of both males and females were significantly extended, suggesting that vitamin D signalling provides health benefits throughout the body," explains senior author Tohru Ishitani. "Our work suggests that vitamin D signalling could influence the longevity of other vertebrates, including humans."

The discovery that germ cells affect longevity differently in males and females could help unravel the links between reproduction, ageing, and lifespan.