Why do women live longer than men?

Will Durant, the prolific historian and philosopher, once said something like, “women are so powerful that if it wasn’t for men keeping them oppressed they would take over everything.” But I can’t find the exact quote.

I don’t believe that. But women do live longer than men. Females living longer than males seems to be true of most species of mammals. A recent study report shows that this is a matter of genes and hormones in mice. (1)

Males have sex chromosomes XY and females have XX sex chromosomes.The only genetic difference between males and females is that males have a Y chromosome with the gene called Sry that females don’t. This gene launches the cascade that causes the development of male sex characteristics. If you don’t have this Sry gene you turn into a girl. So men have everything women have chromosomally and then the Sry gene.

Three women researchers from the department of neurology at the University of California, San Francisco made 2 kinds of novel mice- XX mice with testes and XY mice with ovaries. They did this by removing the Sry gene or moving it to a different chromosome from the Y sex chromosome. Then they compared these novel mice to regular XX female mice and XY male mice.

They found that XX compared to XY increased life span some and that having ovaries, with or without the Y chromosome, helped a little, but having both ovaries and XX sex chromosomes, that is being a regular XX female, made the most difference in longevity.

So that raises more questions than it answers.

All of your cells have 2 copies of every chromosome except in the case of XY males. The Y chromosome has very few genes. Just having a backup can prevent problems arising from 1 bad copy. It could be that ovarian hormone-estrogen, is helpful, or that testes hormone-testosterone is harmful. We used to think giving women estrogen after menopause was good for everything. I even wanted to take it. But the 2002 Women’s Health Initiative (WHI) of the National Institutes of Health (NIH) found that wasn’t so. All cause mortality was lower when female hormones were begun earlier, between age 50 to 59, but higher when begun after age 60. In older patients, there was an increased incidence of breast cancer, heart attacks and stroke, although a reduced incidence of colorectal cancer and bone fracture. So just taking estrogen may not be a good idea. Trying to get closer to the cause of better longer life in females could help find ways to improve the lives of both sexes.

Men and women really are different in size and shape and they come from different planets.

1. Davis EJ, Lobach I, Dubal DB. Female XX sex chromosomes increase survival and extend lifespan in aging mice. Aging Cell. 17 December 2018. https://doi.org/10.1111/acel.12871