Conventionally, it is assumed that the reason for the remarkably persistent gap between men’s and women’s lifespans is cultural. Men are less likely to seek physical or mental health care when they’re in pain or injured or ill, less likely to get routine preventative care, less likely to eat nutritionally and exercise regularly and floss their teeth and all the rest of it.
However, some scientists suggest that part of the reason for the difference in men’s and women’s lifespans may, in fact, be biological.
Across species, mitochondrial DNA is only inherited from the mother: the egg has all the parts of a cell, including the mitochondria (which has different DNA from the rest of the cell), while the sperm only provides DNA. Therefore, natural selection only screens for mitochondrial DNA that is helpful (or at least not harmful) to females. If a mutation is only harmful to males, then it is passed along– even though it reduces the lifespan of males. That may be part of the reason that the lifespan gap remains so stubborn.
Of course, this is based on a study of fruit flies, so it may not generalize to humans (although there’s no reason to believe that it doesn’t) and we don’t know how large the effect size is. And it’s certainly not to say that we oughtn’t change cultural norms so that it’s acceptable for men to take care of their health the same way that women do (while avoiding forcing men to endure the pernicious body-policing that women face). However, it does suggest that maybe this is another case where biology means that equity is not equality. Just like nearly all deaths in childbirth will be of women, just like most women have to put up with periods or menopause when men won’t, just like women as a whole will be less strong than men as a whole, just like many men can pee standing up and most women can’t, just like most men will get far less input than women about what happens after a child is conceived, men may tend to live less long than women do. The unfairness of biology.
Women live longer than men because women have a lower bone density. Read my article,”Alcohol, Aging, and Curing Cancer” by Robert Rainer, MD.
Women on average live longer than men *currently in the industrialized world*, but that does not mean that this is the way that it’s always been. You can’t take women’s longer life expectancy as a given.
Do we know of any society where women have not on average lived longer than men?
India prior to industrialization, IIRC. (Can’t cite anything, just something I read that stuck in my brain from a long time ago, so take it FWIW.)
Women on average live longer than men *currently in the industrialized world*, but that does not mean that this is the way that it’s always been. You can’t take women’s longer life expectancy as a given. The mitochondrial factor may make a difference, but I suspect the major differences are still social, cultural, technological, historical, etc. It has certainly NOT been a historical constant that women live longer than men. Women outliving men may actually be a very recent development in the history of Homo sapiens. This may just be one of those recent First World situations that’s an aberration.… Read more »
That makes no sense. A woman’s *inclusive* evolutionary fitness strongly depends on the fitness of her children – both male and female. If she carries a mutation that harms male children, whether it’s mitochondrial or not, natural selection *will* act on it. There is probably a bias due to the fact she herself is female, but that bias is not and can not be so strong that you would talk about male-only mutations not mattering.
But if the harmful effects only become apparent in post-reproductive years, inclusive fitness “doesn’t t see them”.
First, men don’t have menopause and post-reproductive years; they can reproduce well into old age. Second, as long as individuals are alive (even if they are post- or non-reproductive), they continue to affect their inclusive fitness by e.g. helping out their descendants and other relatives.
Most men have post-reproductive years, where their lower sperm quality and tendency towards impotence make conception highly unlikely. Not to mention that few women of reproductive age are interested in old men, especially without strong social incentives. And when older men do manage to reproduce, the offspring tends to be notably less healthy. One of the core tenets of evolutionary psychology (and biology I’d guess, but evolutionary psychology is in my field) is that the evolutionary impact of something is reversely proportionate to how late in life it manifests. Something which starts to affect you negatively in your 40s will… Read more »
All of this is true, but not addressing the issue at hand. This statement in the post is wrong: > Therefore, natural selection only screens for mitochondrial DNA that is helpful (or at least not harmful) to females. If a mutation is only harmful to males, then it is passed along– even though it reduces the lifespan of males. Like you say, mutations that affect only late life, or that trade off a benefit in early life vs. a problem in late life, are not necessarily selected against (and sometimes they’re selected for). But that’s a completely different claim to… Read more »
And just by coincidence, there was an article in my local newspaper today about the lifespan of orcas or “killer whales” (Willy, you know… ) According to the quoted research, orcas may have the biggest age gap among all mammals, as the females usually live to be around 80-90 years old, while the males rarely get older than 30-40(!). A side effect of this is that, as the female orcas much like humans usually hit the menopause in their early 40’s, It seems to be extremely rare of any male offspring to survive their mother. No mentions of mitochondria, though…… Read more »
So, it’s as simple as DNA. Can’t do anything about it. Health care, both physical and mental, it doesn’t matter. It’s predetirmined! Thanks for clearing that up!
… Okay, really I’m sorry I thought this was supposed to be about uncovering anti-male discrimination, not covering it up, with the barest of faux science.. Also:
http://www.cloisterstudy.eu/index-Dateien/COMMS.htm
So no, the results don’t generalize to humans in any major way. When men and women face similar conditions (as in this study) they have similar life expectancies.
I love it when the uninformed dismiss science just because it doesn’t match their preconceived notions.
Also, try reading your own links- that study found a small (<1 year) biological aspect.
I’d like to see the original study for this, because quite honestly, as a scientist, I cannot trust science reporting to be accurate. Mitochondrial DNA has EXTREMELY little role on your actual biology. It controls your mitochondria, the end. Mitochondria are like domesticated cells living inside your cells that help you convert food into fuel. They are not gendered. They can’t tell the difference between a male cell and a female one, unless they bumped into the barr body or something, I suppose. (Barr bodies are inactive X chromosomes – women only use one at a time in their cells)… Read more »
Yes, but the mitochondria have effects on the rest of the cell, and slightly damaged ones may cause problems (free radical release, just plain being less efficient, etc). I’m currently involved in a collaboration focused on mitochondrio-nuclear mismatch in hybrids (since the mitochondrial genes can move back and forth from the the mitochondria to the nucleus, in hybrids there’s a greater chance that something will go missing), and the hybrids tested so far show significant declines in aerobic capacity at the whole-organism level.
I’ve seen some (unconfirmed) statements about 75-80% of all “spontaneous” or “natural” miscarriages being male fetuses. I don’t now if that is anywhere near the truth, but if it is, I reckon that any defects in mitochondria plays a bigger role here than towards the end of a 65-80 year lifespan.
It is stress, pure and simple…..
I never won an argument with my mother, but I did fight her to a draw once. She was on a tear about my Father or her children, or maybe both and I said “Well since mommies mostly outlive daddies and often outlive their sons; how hard can it really be?”
Still, you can extend even men’s life way beyond what they currently are. Look at what Japans life expectancies are. And compare them to e.g. Russia.
I’m pretty convinced there’s a biological component involved. Though if that’s true, it raises a number of interesting ethical and practical questions. E.g. should men be awarded pensions more younger? Currently, there only exist countries where women are allowed to retire before men.
And it does put the pay-gap in a different light. It’s kind of fair to give men a bit more of the slice, since they get to enjoy it way less.
A biological basis for this trend (or, at least part of the trend) doesn’t necessarily have to be mitochondria, even though that’s what the fruit flies are all about, apparently. If you’ve got a species with two sexes, one of which has two copies of one sex chromosome (like… XX) and the other has one copy of two chromosomes (like XY), you would expect to find that the heterozygous (XY) sex would be more vulnerable to genetic problems effecting the sex chromosomes. If you’re male, and there’s a mutation on your X-chromosome, there’s no back-up copy without the mutation. Hence:… Read more »
Yeah, was thinking the effect size of X linked recessive conditions is much more likely to have an effect on life span than mitochondrial DNA effects (just because it’s unlikely that a mitochondrial DNA mutation is fairly unlikely to effect men exclusively). Lots of X linked diseases out there.
Um, wow…
I’m sorry if this is a little combative, but this sounds a lot like saying biology is destiny. Which is really, really not cool.
I think zie’s saying that biology presents us with facts. Science is facts sometimes, I’m afraid. I wanted to get an oophorectomy for a while until I discovered that removing my ovaries increased my mortality rate by a huge double-digit percentage across the board if I got it done this far from menopause. That’s not misogyny or shaming or assigning a moral value or whatever you’re assuming, that’s just -life-.
In some cases, biology is destiny. You can’t change what’s written in your genetic code (yet), so if what’s written is a genetic disease, then there’s no avoiding it.
What makes you say that “the lifespan gap remains so stubborn”? My understanding is that the gap has been shrinking quite quickly for years.
Earlier this year, British experts predicted that in less than 20 years, men’s lifespans will match or exceed women’s (for those men who reach age 30 — men still die younger at elevated rates due to more risk-taking activities):
http://www.medicaldaily.com/articles/9648/20120423/men-life-expectancy-life-choices-women-gender-sex.htm
I can’t imagine that natural selection with respect to mitochondria would be the reason for women living longer than men since we’re talking about women living to like, 80 and men living to like, 70, at least in stable, developed nations. If mitochondria is the cause of that, women would hit menopause before feeling any effects of crappy mitochondria so it seems to me natural selection wouldn’t screen for that either.
I think here you’re assuming that the mitochondria just kind of break down at a certain point with old age. For all we know the adverse effects are lifelong and start early, eventually resulting in a shorter life for a man (by however much, probably not the full span of difference) — and also preventing women with bad mitochondria from reproducing.
If that were the case, we’d presumably expect the gap to be proportional to remaining life expectancy. But life expectancy at birth is 80.9 for women and 76.0 for men, about 6%; at age 65 it’s 20.3 for women and 17.6 for men, about 13% (United States, 2009 data).
http://www.cdc.gov/nchs/data/hus/hus11.pdf
I think perhaps like most things, Biology plays a role, society pressure play a role, and so does the lack of male specific health care plays a role. The problem I have is that the last one is completely ignored.
What you say is tI think it is important to note that this can only be a small part of the life expectancy gap. The most revealing fact (in the developed world) is that, excepting those diseases or circumstances which are sex-specific, more males than females die in every age cohort of pretty much every known cause. So it is not just disease and illness, but accidents, violence, negligence, suicide, you name it. There is research suggesting that not only are men less likely to seek help with their own physical and mental health problems, but from birth onwards, parents… Read more »
I seem to have lost a few words there! Should have started “What you say is true, but I think…”
What the author says may be true. But it may be false. We don’t know. It bothers me society doesn’t recognize this as an issue worth probing. It seems that male life is valued less by society than female life. More men commit suicide, more men are murdered, more men die in accidents, more men are killed in wars . . . And then, if you are a man lucky enough to die of old age, you will likely die earlier than women. That kinda of seems like a big deal to me. I think that we should be talking… Read more »
While the evolutionary logic is sound, and they’re sure to find other examples, I would be cautious about saying that women live longer because of immutable biology. I mean, either way, culture still shames health conscious men, and either way that is a bad thing.
Doesn’t exactly help that we’ve had a long period of funding women’s health and men’s health hasn’t had too much, at least from what I see in Australia. I know estrogen has a protective effect but I think there is quite a lot of cultural problems to deal with for male mortality such as job deaths, not going to the doctor, suicide, drug n alcohol abuse, violence, etc. Biology may explain some but I have seen that used as an excuse to ignore male issues, acting like the gender gap in lifespan doesn’t matter much because it’s biology and out… Read more »
Since when do we just accept things like this on the basis of biology? We go to rather extreme lengths to compensate for women’s biology. I’d say lifespan is rather worth compensation.
I think that’s what Ozy meant about cultural norms. Unfortunately, if the issue is mitochondria, those are in every cell in your body. “Compensating” for that directly sounds like something we’re decades away from. *IF* that’s causing problems and *IF* those problems are significant (i.e. if on average, a man loses three days of his life to this. Yeah, that sucks and I’m sure those three days really matter when you’re right up against them, but we’ve got bigger problems) then we’re probably decades away from an effective way to counter act it and bets are good it’s got side… Read more »