Are scientists close to solving the mystery of women's longer lifespans compared to men?

A recent study found that the mystery behind women living longer than men may go back to the smallest and largest cells in the body: sperm and eggs, which are essential in human reproduction.

Scientists at Osaka University in Japan have shown for the first time in vertebrates that cells that develop into eggs in females and sperm in males lead to sex differences in average lifespan, and that removing the cells results in animals with the same life expectancy.

The experiments were conducted on small, turquoise-colored killifish, a species that lives in freshwater and reaches sexual maturity within two weeks and lives for only a few months. As in humans, female killifish live longer than males. Scientists therefore suspect a similar biological mechanism that could affect the age gap in humans and other species as well.

Professor Toru Ishitani, senior author of the study at Osaka University, said: “The aging process in killifish is similar to that in humans, so I don’t think humans are necessarily more complex. I think this research will serve as a starting point for understanding the control of aging in humans.”

Globally, women live on average about 5% longer than men. Many factors contribute to this disparity, with young men being more likely to die in accidents or through suicide, and women often following healthier lifestyles. But this disparity appears in other species as well, where female great apes and Old World monkeys tend to live longer than their male counterparts.

For humans, the size of the gap in life expectancy varies widely between countries.

The presence of sperm or eggs was one of the most obvious differences between males and females, so it makes sense to check whether they have an effect on lifespan, Ishitani said. In a series of experiments, his team showed that disrupting the production of germ cells, which develop into sperm or eggs, resulted in longer-lived males, and females died younger than usual, essentially closing the lifespan gap.

“We expected that removing germ cells would extend the lifespan of both males and females, but it only lengthens the lifespan of males and shortens the lifespan of females,” Ishitani explains. “It was unexpected, but we realized that this finding might shed light on sex differences in lifespan.” .

Based on the findings published in the journal Science Advances, female killifish that had no germ cells had less estrogen and more growth factor signals, leading to health problems and accelerated growth. Conversely, male killifish showed improved health and increased vitamin D production in their livers. This suggests that vitamin D may enhance longevity, leading to further testing with supplements.

It is unclear whether sperm reduces men's life expectancy, but researchers said there is some evidence to support the idea.

The study concluded that the discovery that germ cells affect longevity differently in males and females could help uncover the links between reproduction, aging and longevity.