It’s a well-known fact that men tend to live shorter lives than women. A new study confirms this again on average, men die about 5.4 years earlier than women worldwide. The exact number varies from country to country, but the overall pattern remains the same across all cultures.
In the United States, for example, men’s life expectancy is 5.8 years shorter than women’s. The main causes include accidents, diabetes, suicide, homicide, and heart disease (Yan et al., 2024). But why does this difference exist at all?
A recent study published on October 1, 2025, in Science Advances looked at this question from an evolutionary perspective. The researchers wanted to see if this life expectancy gap also appears in other animals, not just humans. Their study, titled “Sexual Selection Drives Sex Difference in Adult Life Expectancy Across Mammals and Birds,” examined life expectancy data from 528 mammal species and 648 bird species, both in the wild and in zoos.
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What They Found
Just like in humans, male mammals often die younger than females.
- In 72% of mammal species (381 out of 528), males lived shorter lives than females.
- Only 5% showed the opposite pattern, while the rest had no major difference.
- In nearly 40% of species, females outlived males by a large margin.
On average, female mammals lived about 12 years longer than their male counterparts. Interestingly, our close relatives chimpanzees and gorillas also showed this same pattern.
This shows that the “male disadvantage” in lifespan is not unique to humans. Instead, it seems to be a natural, evolutionary trend found across many species.
However, the pattern was reversed in birds. Among the 648 bird species studied, males actually lived longer than females in about 68% of cases, though the difference was smaller (around 5%).
What Explains This Difference?
The researchers dug deeper to understand why this happens. The most important factor was whether a species is monogamous (one partner) or non-monogamous (multiple partners).
- In species where males compete for multiple mates, males were more likely to engage in risky behaviors fighting rivals, showing off strength, or taking dangerous actions to win over females.
- These behaviors, while helpful for mating success, lower survival rates.
- In contrast, monogamous species where males don’t compete as fiercely had little to no lifespan difference between the sexes.
Another factor was body size. In species where males are much larger than females (like gorillas or walruses), the lifespan gap was bigger. Larger males often face more intense competition and physical stress, leading to shorter lives.
Parental care also played a role. Species where females (or both parents) care for their young tend to take fewer risks and this contributes to a longer life.
What This Means for Humans
The study suggests that men’s shorter lifespans are not just about modern lifestyles they’re part of a much older evolutionary pattern.
Still, human behavior today continues the trend: men are more likely to take risks such as speeding, drinking, smoking, or using drugs, which can lead to health problems or accidents.
The good news? Many of these factors are changeable. Adopting safer habits, managing stress, and leading a balanced lifestyle can all help close the life expectancy gap. Interestingly, being a father may also extend a man’s life parenting naturally reduces risky behaviors and promotes more responsible choices.
Final Thoughts
Men’s shorter lives can be scripted in part in evolution, but biology isn’t destiny. With better lifestyle choices and better social connections, the difference between men and women’s life expectancies needn’t be so great.
