Why Women Live Longer Than Men: New Research Reveals Key Biological and Evolutionary Factors

For decades, scientists have wondered why women live longer than men on average. Globally, women have a life expectancy of about 74 years compared to 68 years for men. While factors such as riskier male behavior, accidents, and conflicts have often been cited, new research offers a deeper look into the biological and evolutionary roots of this difference.

A team from the Max Planck Institute for Evolutionary Anthropology studied lifespan data from 1176 species, including 528 mammals and 648 birds, both in the wild and in zoos. The results show clear patterns: in 72 percent of mammal species, females outlive males by an average of 12 to 13 percent. In contrast, among birds, males live longer than females in 68 percent of species, with a smaller advantage of about 5 percent.

These findings strongly support the idea that sex chromosomes play a role in longevity. In mammals, females have two X chromosomes, which provide a backup against harmful mutations. Males, with one X and one Y, lack this protection. In birds, however, the system is reversed: males have two Z chromosomes, while females carry a Z and a W. This makes female birds the “heterogametic sex,” which appears to carry a survival cost.

But chromosomes alone don’t explain everything. Researchers also found that mating systems influence lifespan. In polygamous mammals like gorillas, baboons, and chimpanzees, males compete fiercely for mates, often through fights or by developing traits such as large body size or antlers. These traits demand significant energy, leaving fewer resources for long-term survival. Similarly, in many bird species, competition and ornamentation among males take a toll, although the overall male advantage in lifespan is much smaller than the female advantage seen in mammals.

Another factor is parental investment. Across many species, the sex that contributes more to raising offspring tends to live longer. In mammals, females often take on this role, which may have favored their longer survival in evolutionary terms, ensuring they remain alive until their offspring mature. In humans and other primates, this investment in offspring survival is especially crucial, aligning with the observed female advantage in lifespan.

There are, however, intriguing exceptions. For example, in birds of prey, females are larger, more aggressive, and more active in defending territories, yet they still live longer than males. Scientists admit the reasons for this remain a mystery and highlight that biology often resists simple explanations.

The researchers also noted that lifespan gaps between sexes are smaller in zoo populations than in the wild. Captivity reduces risks such as predation, food scarcity, and competition, which can otherwise exaggerate survival differences. This may mirror trends in humans, where improvements in medicine, safety, and healthcare have reduced—but not erased—the gap between male and female lifespans.

Experts stress that biological and genetic differences between the sexes are deeply rooted and unlikely to disappear entirely. While medical advances may narrow the gap further, women’s survival edge appears to be a product of evolutionary pressures, reproductive roles, and genetic advantages that have shaped life expectancy patterns for millennia.