While it's long been known that women tend to live longer than men, researchers for years  ascribed the trend to lifestyle differences. But now, researchers in the emerging field of "geroscience," or the study of aging, are discovering some of the genetic and biological factors behind the longevity gap, Clare Ansberry writes for the Wall Street Journal.

Why women live longer than men

According to Ansberry, it is a well-known fact that women tend to outlive men. As of 2017, life expectancy for men was 76.1 years, while life expectancy for women reached 81.1 years.

And researchers estimate that the gap in longevity will continue. According to the U.S. Census Bureau, women's life expectancy is projected to reach 87.3 years by 2060, compared with 83.9 years for men.  

But when it comes to why women live longer than men, Marcia Stefanick, a professor at Stanford University School of Medicine, said researchers know "men and women age differently," but are still "kind of guessing how."

Some of the factors could be behavioral, according to Ansberry. For instance, some studies have found that women are more likely to see a doctor when they're sick. And 85-year-old psychologist Katharine Esty, who interviewed 128 people in their eighties for her book "Eightysomethings," found that aging women tend to put in more effort to stay healthy, while "[m]en will still eat steak and order French fries."

Exploring the science behind the gap

But the differences can't be solely ascribed to lifestyle and behavioral differences, according to David Sinclair, co-director of Harvard Medical School's Paul F. Glenn Center for Biology of Aging Research. "A lot of people say men smoke and work harder jobs, and that's why they don't live as long," Sinclair said, but "[t]here are genetic and biological differences" too.

For instance, after observing the blood of men and women between the ages of 65 and 95, Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine, found men's protein levels changed at higher rates than women's did. According to the study, men's protein levels experienced 600 significant changes, compared with 277 significant changes for women, indicating that "female biology seems to be more stable than men's," Barzilai said.

Separately, Michael Ullman, a neuroscience professor at Georgetown University, has found that a person's sex might influence declarative memory, or the ability to recall things such as specific events or where someone left his or her car keys. According one study by Ullman, both men and women scored comparably on a memory test involving image recollection—until age 70, when a "significant female advantage emerged."

Ullman also found that the positive effects of education on memory ability were more pronounced in women than men. "The sex difference was really striking," he said.

According to Ansberry, sex could also impact how a person fares when diagnosed with Covid-19, the disease caused by the novel coronavirus.

For instance, one recent study found that, after the age of 65, men lose antibody-producing B cells in their blood—but women didn't experience the same loss. The researchers also found that men experienced greater blood inflammation as they aged, a factor that is associated with serious cases of Covid-19.

However, women don't have all the biological advantages, Ansberry reports. Research shows that women experience a rise in blood pressure earlier and at a faster rate than men, according to Susan Cheng, a cardiologist at the Smidt Heart Institute at Cedars-Sinai. Cheng in a study released this year also found that women's blood vessels age faster than men's.

"The assumption was that women simply caught up with men in terms of cardiovascular risk, not that they have different biology and physiology," Cheng said. But they do—and the findings could help illuminate why women tend to report different kinds of cardiovascular diseases with different types of symptoms, Ansberry reports (Ansberry, Wall Street Journal, 7/14).