05.15.135:05 PM ET

Women’s Immune Systems Age More Slowly

One reason why we live longer.

So as if women’s sexual peak coming later in life wasn’t enough to convince you women are the superior sex, here is some new evidence: women’s immune systems age slower than men’s. The stronger the immune system, the better a person is at fighting off infections—and thus one having a stronger immune system later in life is key to living longer. According to a new Japanese study, the number of white blood cells in the immune system decreased for both men and women as they aged, but at least two key types of cells declined at a faster rate. Researchers also found another type of cell that tackles viruses and tumors increased with age, with women having a faster increase than men.