Researchers have identified a clear trend across history, cultures, and the globe: women live longer than men. But why?
According to a large-scale review by Dr. Steven Austad and Dr. Kathleen Fischer from the University of Alabama at Birmingham, the exact reason is still a mystery. But scientists theorize that a mix of biological, genetic, evolutionary, and behavioral factors may all play a role.
Who lives longer, men or women?
Dr. Austad and Dr. Fischer examined The Human Mortality Database, which tracks lifespan trends in 38 countries as far back as 1751. They found that in every recorded year and location, women’s life expectancy at birth surpasses men’s.
This advantage continues across all life stages, too, becoming even more striking in extremely old age. Data from the Gerontology Research Group, a non-profit scientific research organization, shows that 90% of supercentenarians–those who reach the age of 110 or beyond–are women.
An intriguing example of the female longevity advantage comes from Iceland, where between the mid-1800s and early 1900s, the populations contended with:
- Famines
- Volcanic eruptions
- Outbreaks of multiple diseases
Despite these hardships, women consistently outlived men–even in the harshest conditions.
And this pattern still holds true today. In the U.S., women have lower mortality rates for 13 of the 15 leading causes of death, with two exceptions where they have higher rates:
- Stroke
- Alzheimer’s disease
According to Dr. Austad, “We don’t know why women live longer. It’s amazing that it hasn’t become a stronger focus of research in human biology.”
But evidence suggests these lifespan differences result from a complex mix of biological and environmental factors.
Why do females live longer than males?
Here are some possible explanations:
Biological factors
- X chromosomes: Women have two X chromosomes, providing a genetic “safety net” if one develops a harmful mutation. Men, having only one X chromosome, don’t have this backup, potentially making them more vulnerable to certain genetic diseases.
- Mitochondria: Mitochondria, the cell’s energy generators, are typically passed down through mothers, only. Because they evolved to function best in females, some scientists posit that this may give women a cellular advantage during the aging process.
- Estrogen vs. testosterone: Estrogen has anti-inflammatory and heart-protective effects, reducing women’s risk of cardiovascular disease before they enter menopause. Testosterone, on the other hand, may contribute to higher risk-taking behavior and weaker immune function, which could factor into men’s shorter lifespans.
- Stronger immune systems: Research suggests that women often have more robust immune systems, helping them combat infections and certain chronic diseases more effectively and efficiently than men. This explains why, historically, men have died at significantly higher rates than women during pandemics.
Evolutionary perspectives
- Riskier behavior & survival trade-offs: Throughout history, men have engaged in more dangerous activities, such as hunting, fighting in wars, and long-distance exploration. These “riskier lifestyles” might have contributed to shorter lifespans over generations.
- Parental investment: Historically, in humans and in many animal species, females have been the primary caregivers–an evolutionary role that may have resulted in greater longevity.
But are women healthier than men?
While women live longer, they often experience more chronic illnesses than men–especially in old age. Likely due to their connective tissues being more responsive to hormones, women have higher risks of developing:
- Osteoporosis
- Arthritis
- Chronic pain
These conditions can lead to higher disability rates, meaning that while women live longer, they often spend more years in poor health than men.
Scientists don’t have a definitive answer yet, but it’s likely that a mix of genetics, hormones, and behavior contributes to women’s longer lifespans. Dr. Austad and Dr. Fischer are eager to keep exploring this mystery, as they believe uncovering the reasons behind it could help all of us live longer, healthier lives.
References:
Sex Differences in Lifespan – PubMed
Molecular Mechanisms of Sex-Related Differences in Arthritis and Associated Pain – PMC
Low back pain and osteoarthritis pain: a perspective of estrogen | Bone Research
Parent-of-origin differences in DNA methylation of X chromosome genes in T lymphocytes – PMC
Estrogen accelerates the resolution of inflammation in macrophagic cells | Scientific Reports
Sex differences in immune responses | Nature Reviews Immunology
The 1918 Influenza Epidemic’s Effects on Sex Differentials in Mortality in the United States – PMC
All of which seems like an unstoppable force pushing us towards death but several lines of evidence suggest there are brakes that can slow its progress. For instance, a common diabetes drug, metformin, can modestly slow ageing in mice. And simply changing one gene involved in cell metabolism in a roundworm can lead it to live many times longer than its parents; while it is unlikely the same changes would help more complex organisms, it hints that ageing is not beyond our control. Ageing is a surprisingly plastic process that can be manipulated, de Magalhaes says.