Key Points:
- The difference in life expectancy between men and women is a global phenomenon, and some of it is due to biological differences.
- Some of the reasons women outlive men include variations in immune system, heart, and brain development and health.
If you do an online image search for “reasons why women live longer than men,” you’re bound to find an endless stream of memes of men doing obscenely risky tasks or extracurricular activities with some variant of the title “this is why women live longer than men.”
Here’s a good one:
My personal favorite is a man testing to see if he can pull his hand away faster than a bear trap can snap shut when triggered.
This idea, however, isn’t just a joke—it’s a pretty well-established fact that men don’t live as long as women. According to a 2016 study, The difference in life expectancy between men and women is a worldwide phenomenon, suggesting that there are indeed biological differences. In the US, life expectancy among U.S. men was 73.5 years, compared to 79.3 years among women. And it’s not just limited to humans—females live longer than males in many mammalian species.
In humans, the gender differences in lifespan can be explained by a variety of factors, and some of the more obvious ones are social and cultural.
Macho, macho man
In the song by the Village People—also known for “Y.M.C.A” —there’s several verses of lyrics of what makes a macho man:
Every man ought to be a macho, macho man
To live a life of freedom, machos make a stand
Have your own lifestyles and ideals
Possess the strength of confidence, that’s the skill
And it is precisely what’s described in those lyrics that lead men to do things that result in shorter lives. Men are more likely to:
- Have dangerous jobs and take greater risks: Men far outnumber women in some of the riskiest occupations, including military combat, firefighting, and working at construction sites. Men are also more likely to play riskier and more dangerous sports.
- Avoid doctors: According to the Agency for Healthcare Research and Quality, men are far more likely to skip routine health screens and far less likely than women to have seen a doctor of any kind during the previous year.
- Commit suicide: This is true despite the fact that depression is considered more common among women and women make more (non-fatal) suicide attempts. Some attribute this to the tendency for men to avoid seeking care for depression and the cultural norms that discourage men from seeking help for mental illness. This may also be linked to men being less socially connected.
But social and cultural factors aren’t enough to explain all of the differences seen between men and women.
The inherent handicap of the Y chromosome
The uneven playing field for boys starts early. As we learned in high school science class, all men have an X chromosome and a Y chromosome, while all women have two X chromosomes. The Y chromosome tends to develop mutations more often than X chromosome and the lack of a second X chromosome in men means that X-linked abnormalities among boys are not “masked” by a second, normal version.
Underdeveloped immune systems
Male fetuses may have less developed immune systems because male placentas have higher levels of regulators of fetal growth, while female placentas have higher levels of genes related to immunity. This suggests that male fetuses and placentas prioritize growth at the expense of themselves and the mother. Pregnancies carrying female fetuses also have a more regulatory immune response, whereas pregnancies carrying male fetuses have a stronger inflammatory response. One direct consequence of a less developed immune system is that boys tend to be more vulnerable to infectious diseases.
Brain development and consequences of actions
The frontal lobe of the brain — the part that controls judgment and consideration of an action’s consequences — develops more slowly in boys and young men than in their female counterparts. This may contribute to the fact that far more boys and men die in accidents or due to violence than girls and women. Examples include biking, driving drunk, and homicide. This tendency toward lack of judgment and consideration of consequences may also contribute to detrimental lifestyle decisions among young men, such as smoking or drinking to excess.
Reproductive function
During periods of stress such as starvation, females use available amino acids to create deposits in the liver to support reproduction; conversely, males slow down anabolic pathways and reserve carbohydrate stores for eventual use by the musculature
Heart health, blood pressure, and cholesterol
Men die of heart disease more often and at a younger age. In fact, men are 50% more likely than women to die of heart disease. Medical risks, such as poorly treated high blood pressure or unfavorable cholesterol levels, may contribute as well. The fact that men have lower estrogen levels than women may be part of the reason. Scientists believe that estrogen can help reduce harmful cholesterol levels, which can help combat heart disease. Estrogen also has antioxidant properties that can protect against free radicals, which can damage cell components and cause mutations.
Mitochondrial stress and mind melting
Recent studies report that female mitochondria generate half the amount of unstable molecules called reactive oxygen species compared to the mitochondria of males and contain higher levels of antioxidant enzymes and compounds. Part of this can be explained by the effect of the sex hormone estrogen, which increases the expression of genes associated with longevity. These genes include those that encode the antioxidant enzymes, resulting in reduced reactive oxygen species production of mitochondria in women, possibly contributing to the longer expected life span of women compared with men.
Mitochondria-related stress in the form of reactive oxygen species play a key role in neurodegenerative diseases, such as Alzheimer’s disease. The brain of Alzheimer’s disease patients is marked by severe synapse and neuronal loss, atrophy, and depletion of neurotransmitter systems in the hippocampus and cerebral cortex. Recent findings suggest that these changes are induced by mitochondrial dysfunction and increased oxidative stress.
Metabolism and muscle
Men and women differ in several metabolic characteristics. At the molecular level, women have lower fasting insulin and glucose levels, lower basal fat oxidation, and higher fat use but lower consumption of carbohydrates during physical activity. The most noticeable difference is the fat distribution, so that men tend to have more visceral fat, whereas women have greater fat deposition in lower body depots. For healthspan, the above-described traits tend to favor women such that they have a lower risk of cardiometabolic diseases (before menopause).
Sex-specific responses to lifespan-extending molecules
The biochemical effects of any molecule on women and men can differ significantly. In fact, researchers have shown that biological sex is a crucial factor in the effectiveness of anti-aging drugs. This applies to the promising anti-aging drug rapamycin, which prolongs the lifespan of female fruit flies and improves gut health, but not that of males. Another example is a non-feminizing form of estrogen, called 17α-estradiol, which can increase the median lifespan of male mice by 12–19%, but does not have a significant effect on the maximum lifespan. Interestingly, this increase in median longevity seems to be attributed to improved metabolism. 17α-estradiol does not affect the lifespan of female mice, even at higher doses.
The take-home message
There’s still quite a lot to be learned about how differences in sex affect aging and longevity. Scientists are still trying to figure out why women age better than men and live longer. They are looking at a combination of genetic, hormonal, and behavioral factors.
And if you’re a man, maybe consider not doing that dangerous thing that may make you look and feel more macho…at the end of the day, it may be the reason you live a much shorter life.
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