Why do women live longer than men?
April 9, 2005 6:19 AM   Subscribe

Is there a proven biological explanation why women live longer than men?
posted by plainfeather to Science & Nature (24 answers total)
 
Dunno, but if the average age is a mean, it would include people that died at any time of life. So if more men in their 20's died it would bring the average life expectancy down.
posted by lunkfish at 7:37 AM on April 9, 2005


War, risky behaviour.
Is there a difference after age 40?
posted by weapons-grade pandemonium at 7:49 AM on April 9, 2005


i doubt you can separate out the effects of damage done in youth to males who still survive past any particular cut-off age, so even if there is a difference above 40 (i believe there is) it still wouldn't be clear whether it was due to the behaviour of young males or not.
posted by andrew cooke at 8:00 AM on April 9, 2005


There is about a seven year difference in the life expectancy of (American) men and women. A number of explanations have been posited. I suspect that they are all true, to some degree.

1. Women are smaller, and smaller people have longer life expectancies. Tall guys die five or six years earlier than shorter guys.

2. Men store their fat in their gut, where it is more mobile, and leads to heart disease and arterioschlerosis. Women store it in their butt and thighs, which is safer.

3. Women, being more nurturant, generally have better social networks, which is positively correlated with longer life.

4. Women are somewhat more inclined towards religious faith, which also correlates with longer life.

5. Men live their life under more stress (from work and financial worries, status anxiety, and physical labor) which is corrosive to the body and shortens longevity. I am not endorsing this theory, just repeating it.
posted by curtm at 8:26 AM on April 9, 2005


It's a good question.

This suggests menopause and evolutionary favouritism (and safer birthing practices) coupled with hormonal differences that cause more heart attacks and strokes in men are the main causes. But they say the life expectancy of men and women have converged in the last 20 years because more women have taken up stressful occupations, previously dominated by men.

This one is more forthright: "..while 70-year-old men have the hearts of 70-year-olds, those of their female peers resemble the hearts of 20-year-olds.."

I'm thinking there's no definitive answer. I could look further but I'm dying first so I don't have enough time.
posted by peacay at 8:31 AM on April 9, 2005


But then again, you said biological explanation - that would rule out the social / religious / nurturing sides of things. I think those 2 articles cover all the known biological elements.
From my own thoughts I'd imagine that a difference in brain chemistry (for example: endorphins are stored in women for easy release, whilst men need to manufacture them at the time of need - my understanding) would contribute significantly to degrees of stress. Just by the by....this example both explains why women have a higher pain threshold generally than men and also why such things as a specific measure of alcohol for example can have more effect in a woman than a man, after taking into account body mass and other metabolic differences. All of it means a biological basis for a life of reduced stress levels.
posted by peacay at 8:47 AM on April 9, 2005


But then again, you said biological explanation - that would rule out the social / religious / nurturing sides of things.

Not necessarily. The whole social/religious/nurturing correlation might just be a proxy for more fundamental underlying biological causation. For instance, since women are more connected to social networks, they're more likely to be prodded by friends and relatives to get their health problems taken care of. They thereby wind up with better medical care, which is a pretty sound biological explanation for living longer.
posted by mr_roboto at 9:34 AM on April 9, 2005


mr roboto maybe, but it's a long bow.
All of those observations about a woman's life are actually social phenomena. Ascribing a biological basis to them (which is not exclusive to women by any means) virtually negates the influence of family/upbringing/nutrition etc. I'm not saying there's zero basis, but I think it's controversial if not arguable, at best.
Good healthcare may equally come from success in marrying rich or independent economic success or, especially these days, being better informed by having access to such things as tv (heaven help us) and the internet not to mention better insurance plans (maybe).
But it's why I liked the poster's question - this is not a subject where it's yes or no. I imagine if we went googling properly we would both find a myriad of biological theories.
posted by peacay at 11:03 AM on April 9, 2005


I would imagine that there's a good evolutionary rationale for women living longer: we're more valuable from an evolutionary perspective, since the number of women, rather than the number of men, is largely the limiting factor in propagating the species. Additionally, I'd expect that we'd need to be made of sterner stuff, since we (historically) have had to survive through a much more tramatic biological event as a matter of course than most men do. Of course, where this theory breaks down is in old people; after women reach menopause, men of the same age become more valuable reproductive capital. Still, maybe the effects of keeping women alive long enough to reproduce carries on through our twilight years.

On the other hand, I have never, ever heard a woman yell, "Hey Clyde! Watch this!" That probably accounts for a lot of it.
posted by LittleMissCranky at 12:11 PM on April 9, 2005


Another explanation is that women are more likely to seek medical help then men, therefore if women have a life threatening medical issue it will be treated as opposed to the men. Thats more of a social explanation but we also learned that a man's heart loses 25% of its pumping power by the time he reaches the age of 70.
posted by bluehermit at 12:21 PM on April 9, 2005


My question was indeed searching for a biological reason for female longevity, and asking if readers were aware that any had been proven. I'm thinking: hormones, gender-specific oxidative stress inhibitors on the cellular level, internal chemistry that promotes cardiovascular function, something of that nature. (I'm not seriously suggesting female hormones: otherwise guys would be injecting them like mad, if their efficacy had been proven, or for that matter even suspected.)

The responses to the question were mainly a posteriori speculations of this sort: longevity is limited by stress, therefore most men must lead more stressful lives than women.

Back in the glory days of the Patriarchy, actuarial statistics from life insurance companies showed that women lived 2-3 years longer than men. This was reported frequently, indeed almost eagerly, in such publications as the Sat. Evening Post and Reader's Digest.

It was assumed that this was due to embattled males reveling in stress at the office, although nobody could ever convincingly explain what was less stressful in the life of a housewife bringing up 2-3 children, doing the ironing and getting dinner on the table before the breadwinner returned home at 6pm.

In the mid-Sixties it is suddenly announced by the Surgeon General that smoking inhibits longevity. Now here was a reasonable explanation for the statistical gap: since guys smoked a lot more, and indeed heavier items like unfiltered Camels and Cuban cigars when affordable, they are obviously going to die earlier, of pulmonary and c/v diseases.

Come the late 90's, and women are now on the job market and most people have quit smoking. And the middle-aged population starts to ingest anti-oxidants like nobody's business.

Are we in a statistical time-hole, waiting for new data to confirm equal longevities due to life-style changes?

Or is there an internal biological explanation for female age-dominance? In fact, is there any present research going on somewhere?
posted by plainfeather at 12:22 PM on April 9, 2005


We really need a flag for 'serious academic question' as opposed to 'passing whimsy'. But I think there's hard data - some alluded to in the 2 articles I cited - perhaps not gold standard sources of course.
Are you researching something? Have you formed an opinion or do I note some subtextual exasperation from bygone scientific fallacies?

(btw: hormonal differences are significant and if I accept at least some of that 2nd article's propositions, then women have less total risk to atherscleromatous plaque formation - there's obvious 'sideaffects' for a man regularly injecting female hormones that only transexuals and the like would want to endure - and even then, it's not merely the presence of these hormones, but the whole profile of hormones in a rhythmical cycle that would accord a lifetime benefit)
I'll have a look around though to see if there's anything recent online.
posted by peacay at 12:50 PM on April 9, 2005


One explanation I've heard that I don't know if it's true, is that women get sick more frequently when they are young, either due to contamination from sick kids or just more susceptability. On the other hand, men get sick most when they are older, and correspondenly weaker in general health and then tend to die from it.
posted by stoneegg21 at 1:37 PM on April 9, 2005


I'm very sure that it's not more stress faced by men, rather it's that women are more biologically capable of handling the stress. I am 97% sure that the endorphin explanation I outlined above has a role. (I didn't look it up - there's probably something around but it's certainly only come into view in the last decade or so)

Some proven biological facts:

1. Testosterone production gives men a lifetime risk because it promotes sclerotic changes in blood vessels. (see 3.)

2. The profile of hormones in a normal female cycle over 30 or more years confers risk protection against sclerotic vessel changes. The vessels are generally more pliable and less damaged by the time of menopause - the rate of damage and sclerotic risk will increase thereafter but it will be from a 'lowered baseline' versus men. It's also logical - more pliable vessels to ensure blood flow to an embryo. (But men still have testosterone effects past the average age of menopause in women, that will continue to ramp up their mortality rates)

3. Oestrogen promotes high density lipoprotein (HDL) formation by the liver with attendant efficient use of fats. (LDL's are by comparison more easily produced in males and are 'sticky' for blood vessels - and the deleterious effects in men are also enhanced by the tendency towards less exercise than way back in cave times)

4. There are suggestions, from some articles I've perused (which tended more towards reviews than being primary sources, internet being somewhat limited in the 'free' sector in science, of course) that oestrogen significantly bolsters immune protection for all major organs - and again, that will be 30-odd years of comparative protection from damage versus males.

5. Testosterone does in fact increase the level of aggression resulting in all those accident/fighting/car accident/risk taking statistics that contribute to the life expectancy charts.

So, if you want actual hard data for citing in a paper, then I'd suggest that you go to a University library and search around on some of these terms. It's difficult without access to obtain current articles.

(I played around here, by the way)
posted by peacay at 1:58 PM on April 9, 2005


BTW, women don't actually live longer than men, they're just more likely to.
posted by Aquaman at 3:00 PM on April 9, 2005


One thing I've heard postulated is that too much iron in the blood can lead to heart failure - not so much of a problem for women who menstruate monthly for most of their lives. Men, on the other hand, don't lose blood regularly, and as such have a much higher concentration of iron floating around (this would explain why cardiovascular problems are so much more common in males). Because of this, it's supposedly good to donate blood every once in a while.
posted by borkingchikapa at 3:18 PM on April 9, 2005


Thank you, Peacay, for your very perceptive comments, which force me to define my question further and to examine possible subtexts.

My interest is more concerned with scientific methodology.

We are confronted with an interesting fact: women live longer than men. One would think that this might be a legitimate object of scientific inquiry, but instead a kind of popular mythology (as evidenced by some answers on this thread) has grown up around the issue: women live longer because they are less stressed, or they can react to stress more effectively than men. Interestingly, this explanation existed long before evidence showed that stress contributes to heart problems, and therewith naturally to diminished longevity.

I have to say in this regard that I have known some reasonably distinguished biologists in my time, and they have responded to my question with much impatience.

To me, it is rather like Hollywood's interpretation in the movies during the last 10-15 years of some extreme form of criminal behavior: if you have a rapist or child-molester or serial killer, then the person in question got that way because he was himself the victim of child or parental abuse -- sort of a popular, watered-down, cliche-ridden Freudian explanation about a hundred years after Freud. A possible biological explanation is ignored -- for example, that the serial killer's aggression glands are simply squirting overtime, or whatever -- which actually comes a lot closer to how we explain mental illness nowadays.

I don't see a reason to assume that women handle stress better than men, and I wouldn't know how to measure that. Personal experience is clearly of no value: I've know some comparatively serene women, but also some fairly jumpy ones, and I haven't forgotten that Freud's initial clinical studies involved "female hysteria," which was certainly a very hot issue at the time.

By the same token, if processing stress succeeds better with women than men, it is certainly not proven, for example, that a woman thus endowed, but who does not exercise, will live longer than a man who does.

So then I suppose a more scientific approach to the question of why women live longer would be to enumerate all possible factors of longevity and then try to see where women prevail and men don't.
posted by plainfeather at 3:57 PM on April 9, 2005


plainfeather, I see that you are deeply thoughtful about this topic and I respect that.
And as a primary response I'd ask you to concede that I've shown (not proven, as I'm not pulling up citations - but this stuff is not controversial in the scientific community - a fallacious appelation to authority though it may be in terms of argument formation, nevertheless...) conclusively, at least in the subject of hormonal differences, that there are such significant biological (vascular) ramifications flowing from those differences which would I suggest, on their own, adequately account for the divergence in life expectancies between the sexes, regardless of other more contentious elements.
If you accept these experimentally validated findings as I outined above, then all other contributing factors can be metaphorically tossed into the dustbin of mythology or urban legend or the like, in the absence of validated experimental results. Because with the hormonal effects alone I suggest that you have a tangible, proven basis to explain the life table differences between the sexes. I'm not especially trying to be pedantic about this, I'm just trying to allay what seems to me are misgivings you hold in relation to the validity of studies that you haven't actually seen. They've measured this stuff and it's kosher at least for the sex hormones. I can only ask that you have some faith in scientific integrity and accept it as fact.

But that's not at all meant to ignore your final paragraph above. I think that's a very sensible approach. I'm sure it's been attempted in literature reviews but I'll leave it to you to search.
However, all those other factors will be tricky. As you say, it's hard to measure a 'stress' response when there are so many jigsaw pieces that make it up. It will be hard to correct for environment, nutrition, upbringing, family genetics, behaviour/psychological and social (to name but a few I suspect) etc contributors to such a potential reason for life expectancy difference as ability to cope with stress. And of course each of that list of 'interferences' will have positive and negative effects upon the net life expectancy data - a good diet and exercise and cutting out smoking and having good family genes may nullify other risk factors to which a man is prone and he could go on to live longer than his wife. These lifestyle elements are surely having an effect on the data in the bigger picture, but the discrepancy between the sexes remains - at the population level. At the individual, it's much more complex.

Here's one writeup, indicative of sorts but inconclusive. Worth a look.

And by coincidence this was published today - but I suggest that it is mostly inconclusive, even contradictory and reasonably poor science to boot. But there's reference to what I wrote about endorphins towards the end. I'm sure there's lots of other studies going on. I'll let you search further. But I'm sure that it's down at brain chemistry (and metabolic) level that hard data will be obtained - if this ABC article is correct, then cyclical hormone levels again give women 30-odd years of 'stress protection' by potentiating the release/effects of a range of endorphins.

So there it is. I'm afraid that I'm a little unwilling to contribute further, not because I'm disinterested but this does take time (and I do enjoy problem solving) and I feel that I'm at a bit of an impasse. So I'd urge you to read these 4 papers and perhaps do some more searching yourself (and include google scholar). Maybe later, if you want some other contact or input or suggestions or the like you could email me. Good hunting and thanks for the gristle - good chewing.
posted by peacay at 5:53 PM on April 9, 2005


we're more valuable from an evolutionary perspective, since the number of women, rather than the number of men, is largely the limiting factor in propagating the species.

wouldn't that require fertile women? Men can still reproduce after retiring; from an "evolutionary perspective" we're only 'help around the house' after menopause.

A possible biological explanation is ignored -- for example, that the serial killer's aggression glands are simply squirting overtime, or whatever -- which actually comes a lot closer to how we explain mental illness nowadays.

It's worth remembering that nature/nurture is an artificial divide to begin with. His glands might be "squirting overtime" because of some childhood trauma he underwent, etc. Surely some things are simply arbitrary bad luck, but remember that all of the mind is physically manifest, so you can't take the measurement of a chemical to "prove" that there was no social/mental component. Shakespeare's poems were the result complex mixes of seratonin &c, but that doesn't mean they weren't the result of his personal experiences. All your intense personal experiences are chemical, but they're still mental/personal too...
posted by mdn at 6:52 PM on April 9, 2005


Some of the other contributing factors include:
- Males have higher infant mortality.
- Higher percentage of males smoke.
- More males die in accidents.
posted by raedyn at 7:38 PM on April 9, 2005


remember that all of the mind is physically manifest, so you can't take the measurement of a chemical to "prove" that there was no social/mental component

That speaks to the individual or the small group. But our poster is looking at the population level. That's why a lot of mythology comes into it - because everyone makes their own observations about a generally small number of people. So and so lived to be 412 years chasing women and smoking datura up to the end. He had 'good glands' or the somesuch.
I'm agreeing with what you've written mdn, but at the population level, neurobiochemical differences between the sexes - not between individuals - are measured and they show a range of differences simply because of sex. They affect the life expectancy. The extent of their effect and the ability for non-biological factors such as behaviour/environment etc to nullify those affects are generally determined at the individual level.

Oh...borkingchikapa....Men have a higher blood count (which approximates to iron content) true (in general) but a woman's cycle doesn't really have too much of an effect on her blood count - too little loss per body volume and there's continuous red cell production. Unless there's blood pathology, a man's higher red cell count won't contribute to higher incidence of stroke/heart attack. But donate blood by all means. Just don't count on it conferring any magical protection against the beast that is testosterone.

on prev: raedyn: The infant mortality number differences at the population level must be quite small and I wonder if it isn't a range of anomalies that are causative as opposed to a single identifiable sex-specific risk factor. Accident rates may derive from the beast once again. There's a continuous higher death rate among men in all age groups I'm sure. But all the controversial elements (such as behavioural things like smoking) that contribute to life expectancies comprise only a modest level of influence compared to the sex hormones - at the population level. So methinx. I'm open to being wrong - it wouldn't be the first time - but the hormone studies are very very solid sex-specific risk factors affecting all members of a population.
posted by peacay at 8:12 PM on April 9, 2005


I actually think I probably didn't explain this the best and made a couple of minor errors.

I suppose when thinking about 'real' influences on longevity data of populations, it's better to give little weight to things that have an arguable basis (social stuff for eg.) and be more aware of the things that are universal - sex hormones affect (virtually 100%) all individuals of both sexes in the population.

Think: everyone is affected by 'X' (has big impact on population level expectancy)
Downplay: individuals/particular groups are affected by 'Q' (contributes, but is generally minor in magnitude at the population level)

So oestrogen and testosterone are very (but not fully) explanatory for women having a longer life expectancy.
posted by peacay at 4:35 PM on April 11, 2005


That speaks to the individual or the small group. But our poster is looking at the population level.

a) he seemed to be intrigued by the application of this to individuals as well, with the serial killer example;
b) women are a population that is immediately recognized & hence treated differently as a group. We can argue about how differently women are treated & whether it should have any effect on longevity, but it can certainly be considered a possibility (as suggestions above do).

I don't know enough about the particulars of the stats on this one to state a position, but I just wanted to make the point about the two sides not really being separate. The physical state of things is both cause and effect of the mental state.
posted by mdn at 6:39 PM on April 11, 2005


Maybe I should say at the species level rather than population so as not to be ambiguous. Just meaning that stats for life expectancy come from every death - not just deaths of a certain subgroup or a certain intermittently contributive cause (hence, again, the contribution from sex hormones far and away outstrips all others by virtue of their ubiquitous effects)

That speaks to the individual or the small group. But our poster is looking at the population level. ......Mmmm....just about all of that particular comment of mine was ummm...made in haste, fueled by adrenaline and suffered from lack of sleep. So it goes..
posted by peacay at 8:38 PM on April 11, 2005


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