114 replies to this topic

[pleb]

its quite possible he may support the longevity cause, depending on how far outside the law he is, you can get a doctor to give you a prescription if you have been diagnosed with an ageing problem in the US but the normal dose for anti ageing is only 1 to 2 iu a day, whilst most BBrs use a lot more than that,

I'm not sure exactly how much he uses i know he was stopped by customs at Sydney airport a couple of years ago with quite a few vials of Jintropin in his suitcase, as its totally illegal there,

I've just started 1 iu a day after reading the new England medical school trails from 1990, as its okay over here although its a bit of a grey area, as according to the law you can't sell it or even give it away, but can import it for your own use and don't need a prescription,,
i do know one company that import it and sell it i assume legally i get the impression they simply state they are a forwarding company for the manufacturer in China and sell it as a research chemical, and not for personal use,

Edited by pleb, 07 March 2013 - 12:18 AM.

[YOLF]

My concern with growth hormone is that too much of it might deplete stem cell pools faster. Of course, that might be old school thought.

[pleb]

yes I've read similar reports, if taken in large amounts, but 1 or 2 iu a day shouldn't be a problem even for older adults

for burns victims they recommend 8 iu a day and kids who suffer from lack of growth have taken 7iu a day for up to 2 years in some cases, bb'rs take anything between 4 and 10 iu a day,

and that there are approximately 100,000 older adults in the USA taking 1 iu a day regularly, many get costs reimbursed by their medical insurance company,so it doesnt appear to be a problem at those amounts,, and those amounts are FDA approved,

i've spent quite a lot of time reading up on HGH and have yet to find any deaths caused by it, even at the larger amounts,
side effects vary and are progressive, ie you dont get the worst side effect before the others, they all follow a pattern mild to worst in every case,some report carpel tunnel syndrome at 2iu upwards which disappears after a couple of weeks normally its not reported until you get above 3 or 4 iu a day, this being the mildest side effect a slight tingling in the hands being the first effect to be felt,

other side effects are noted but nothing serious the worst being acromegaly (bone growth) but at over 10 iu to 15 iu a day, and even then it was being given to people who already had bone growth because their own body produced to much,

it was that report of increased acromegaly that the FDA used to get it banned and only on prescription, wildly skewed and probably at the behest of big pharma who were loosing sales to the Chinese stuff which cost 1/10 the price,
i couldn't find any reports of BB rs getting acromegaly although it is possible there are some, and they probably take more over a longer period than any other group, and that any side effects stop if you stop taking HGH, side effects don't persist,

Edited by pleb, 07 March 2013 - 07:42 AM.

[clairvoyant]

Excuse my interference but I had read a study that said that the male's cell membranes have 10% more PUFAs which easily per-oxidize. That may be some explanation.

[jackquack]

In Maximum Life Span, Roy Walford wrote this:

"In fact, however, it's probably not true that women age more slowly than men, because there's no difference in maximum life span between the sexes. The observed differences in 50 percent survivals are secondary to environmental changes in the past half-century. In 1900 there was no sex difference in 50 percent survivals, and there were as many men as women over 75 years of age. The relative upsurge in male mortality Slnce 1900 can be traced to smoking (lung cancer, heart and respiratory disease), more accidents (automobiles), and more alcoholism among males. Where these factors are not operative, as among the Amish, men live as long as women even now. Furthermore, in today's population at large...the difference in remaining life expectancy for men and women narrows as the population becomes older.

"At age 50 men expect to live another 24.5 years; women, 30.4 years -- a difference of 5.9 years. By age 85 the difference in life expectancies is only l.4 years..."

But then again, has anyone surveyed the Amish about their propensity to masturbate?

Edited by jackquack, 16 April 2013 - 06:43 PM.

[YOLF]

Has anyone ever seen their parents/grandparents argue over medical stuff? Men usually spare no expense on their women's health and drop cash without a second thought, and will then forgo treatment for most things and even not visit a doctor for a heart scare while women are getting loads of surgery and medical care and adjustments to their prescription regimens every month. Women on the other hand will also cow a man into a corner if he might create an ER bill. Men die sooner cuz they care more about their women than they do about themselves. Women speed and drive aggressively just as much as men if not more, but most cops are also men and probably look at women as caregivers who should just get a warning. Think about it, you're a cop and you pull over a woman, she probably has kids in the car that are stressing her out and is venting stress pheromones into the air. So you're a guy who just pulled her over and your chemical response is to help her, not give her a ticket. Men might be more stubborn, but this would actually relate to lower T levels IMO. T levels increase confidence, stubbornness is a form of the opposite. So men whose T levels drop are more likely to die from the effects, where women are all getting hormone replacement therapy and are on estrogen for most of their youthful through middle age years.

I guess this results in women suffering through the end stages of life and men just dieing from lack of treatment/care. I suppose we'd have to look at a society where medical stuff is 100% paid for by the state and where men's occupational safety is equal to that of women's. Any ideas?

Though the Amish demographic brings up an interesting point, I don't think their men or women have much in the way of medical care, though I do see Amish people at the Dentist in extreme anxiety from time to time. They adamantly oppose using any kind of pain killer or numbing agent... I've never seen anyone else as frightened as an Amish at the Dentist.

Give up on the masturbation thing! More sex/masturbation means elevated good hormones, means longer life spans! What perspective are you arguing from?

[lemonhead]

Surprised no one has mentioned the 'mother's curse' hypothesis.

From Science Daily:
Now scientists think they may have found the answer in the aptly named "Mother's Curse."
Published in Current Biology, research led by Dr Damian Dowling and Florencia Camus of Monash University in Australia, together with Dr David Clancy of Lancaster University in the UK shows that a set of DNA inherited only from the mother can be harmful to males and speed up male aging.
Dr Dowling said the results point to numerous mutations within mitochondrial DNA that affect how long males live, and the speed at which they age.
He said: "Intriguingly, these same mutations have no effects on patterns of aging in females. They only affect males.
"All animals possess mitochondria, and the tendency for females to outlive males is common to many different species. Our results therefore suggest that the mitochondrial mutations we have uncovered will generally cause faster male aging across the animal kingdom."
Dr David Clancy from the Faculty of Health and Medicine at Lancaster University said this is a major advance in biology.
"We show that Mother's Curse is much broader in its effects on male life history than previously envisaged, resulting in the build-up of mutations that cause males to age faster, and live shorter lives than females.
"These findings …offer a new and compelling explanation to one of life's greatest puzzles -- why the female of many species, including humans, live longer than the males. "
Mitochondrial DNA, which is found in every cell in the human body except red blood cells, converts the energy of food molecules into energy.
It is inherited through the mother only so any harmful mutations which affect only males will have no impact on females, who will continue to pass on mitochondrial DNA to their sons.

Original research paper:
PMID: 22863313
Curr Biol. 2012 Sep 25;22(18):1717-21. doi: 10.1016/j.cub.2012.07.018. Epub 2012 Aug 2.
Mitochondria, maternal inheritance, and male aging.
Camus MF, Clancy DJ, Dowling DK.

Sorry for no links, I'm not allowed to link out yet.

Edited by lemonhead, 22 August 2013 - 02:55 PM.

[lemonhead]

Cryonicsculture, your observations of men's chivalry are not backed up by published research (free full-text available):

PMID: 19645027
Cancer. 2009 Nov 15;115(22):5237-42. doi: 10.1002/cncr.24577.
Gender disparity in the rate of partner abandonment in patients with serious medical illness.
Glantz MJ, Chamberlain MC, Liu Q, Hsieh CC, Edwards KR, Van Horn A, Recht L.



BACKGROUND:

Life-threatening illness creates severe stress that may result in marital discord, separation, or divorce and may adversely impact treatment, quality of life, and survival. The few studies that are available to date have suggested that the risk of divorce is not higher in cancer patients, but to the authors' knowledge, no data exist to date that have examined the effect of gender on this rate.
METHODS:

A total of 515 patients were prospectively identified as having either a malignant primary brain tumor (N = 214), a solid tumor with no nervous system involvement (N = 193), or multiple sclerosis (N = 108) who were married at the time of diagnosis. Basic demographic information and data regarding marital status were compiled. Patients were followed prospectively from enrollment until death or study termination.
RESULTS:

Women composed 53% of the patient population. Divorce or separation occurred at a rate similar to that reported in the literature (11.6%). There was, however, a greater than 6-fold increase in risk after diagnosis when the affected spouse was the woman (20.8% vs 2.9%; P < .001). Female gender was found to be the strongest predictor of separation or divorce in each cohort. Marriage duration at the time of illness was also correlated with separation among brain tumor patients (P = .0001). Patients with brain tumors who were divorced or separated were more likely to be hospitalized, and less likely to participate in a clinical trial, receive multiple treatment regimens, complete cranial irradiation, or die at home (P < .0001).
CONCLUSIONS:

Female gender was found to be a strong predictor of partner abandonment in patients with serious medical illness. When divorce or separation occurred, quality of care and quality of life were adversely affected.


Sorry there's no links, I'm not allowed to llink out yet.

[tham]

As the Life Extension Foundation has emphasized, ischemia is
generally the end-cause of death, whether degenerative, pathogical
or accidental.

Women already have a head start for the first 50 years or so, with estrogen
staving off atherosclerosis.

[extroverinstinct]

Men, I believe more often than women, internalize stress. This definitely increases the potential negative effects normal stress exerts on our systems.

Just one reason among many?

[Layberinthius]

the reason we pick our partner, it’s called the primal urge, the continuation of the species and its hard wired into us and has been since we left the rift valley,
man picks women as child bearers good looking well built women with big breasts that's why many men have fixation with breasts,
but it still comes down to their looks, that first look is what attracts us generally their face, but not always, we pick that person in less than a second, that's how long it takes for us to realise if we are attracted to them as a potential mate,
then we find out what they are like as a person, which can nowadays break the interest,
most men don’t actually like women they are there for two reasons still tied into the primal urge to have the kids and cook the food, and many men still look on women that way they may deny it but its part and parcel of continuing the species,
and why many men chase other women he is driven by his primal urge to make as many kids as he can, so hops from one female to the next monogamy is recent in mans and womens development living as a couple is recent compared to how long he has been on this planet

women pick men as providers the big hunter who will put food on the table, modern society has altered these things but it’s still there hard wired into them, women look for security even if that's just as a couple or for financial security, and will quite often pick someone even if he is not their first choice simply to have the protection they perceive as being part of a couple, like men's picking women its hard wired,
despite their protestations that they are not as bothered by looks as men they will also go for the tall well built guy it's part of their primal urge,

I was going to add my own info to this discussion but I see its already been said.

I believe this guy is the closest on the mark. If my opinion is of any value that is, I'm a pretty new contributor here and not entirely sure just how well I am doing.

I still think stress is a contributor though, especially between the ages of 15-30. But that is due to the modern worlds pressures.

When I was growing up I thought of sex as nothing but fun, I am a virgin though my viewpoint is still valid, to me it was a childish game. Little did I know that when I grew older I would have women screaming in my face telling me just how much of a disgusting human being I was for not taking some kind of personal responsibility for wanting and/or desiring sex. That to me was certianly stressful, to not only find out that women could be nasty and vicious to the point of wanting you to kill yourself, but also that sex was neither desirable nor warranted, and the guilt that I had for owning the equivalent to a lethal weapon in my pants.

All I know for sure is that I am polyamorous and pansexual for good reasons, I have come to terms inside my own mind with what I want, what my mind and my hormones want at least.

I would probably give up the desire of sexual drive (if I knew I could get it back at the drop of a hat, or the flip of a nanobot switch.) in favor for something more exciting like a good puzzle to solve or something else which would be more interesting than sex.

I wouldnt take any sterilization drugs though, I can control my own sexual desires quite well. Anti-depressants, Tobacco and Alcohol are doing a good enough job of sterilizing/impotence-izing men anyway.

It seems to me also that the act of mating is going to be going by the wayside in the future, as more and more people become aware of our severe overpopulation problem.

I know what the solution is though, robotics. I'm sure that a walking, talking, breathing robot that can be programmed to do whatever you like it to do will certianly bring down mens stress levels.

At least thats what I'm waiting out for if no women wants me that is.

And before anyone calls me a mysognist for what I believe in, well once when I was only a 10 year old kid I hit a girl on the legs with a tree branch, but not before she did it to me first, then she screamed for the teacher, so I was obviously the one who got in trouble. Eye for an eye dear. Thats what I believe in. Just because we're not as pretty as you and dont scream doesnt mean you should abuse us just because we're biologically male. It bloody hurt.

And just because you were spoilt by your parents doesnt mean you have to act like a child and remain mentally immature, there are other methods of attracting a male partner. and none of them involve implicating other people in things that you have done.

Frankly it would be better for us all to simply ignore the generation of women who act like idiots. and create a society of xenophobes like the Amish, where a philosophy of being good just for the sake of being good is held in value above all other values, including self profit.

I see on a regular basis how society has designed itself from the ground up to grind down my goals of living forever, everyone wants their cut of money and they are hellbent in making me pay with my own life. All I want to do is get some farmland and start growing my own food and build my own hut, then start learning about a wide variety of topics. Cant even do that without at least $50,000. And then I've gotta pay taxes for the rest of my life on that land.

Honestly, government, who the fuck do you think you are? You are taking away my right as a human being to inhabit a piece of land free of charge. Or rather, the people are, because the people are setting the value of land. Frankly the whole damn system is overburdened with too many damn people wanting the same land that I want. And joe the guy down the road wants, and that cute couple next door want. Overpopulation I have found is the root cause of a great deal of my burdens so far, including finding a potential mate. If there is less resources to go around then I am left with nothing.

I am a very tall guy, and on more than one occasion I have had a shorter guy "steal" the woman who I was interested in, but more than that, the woman wasnt even interested in me in the first place because I was too tall and therefore considered to be a freak. Or in her terms "I just dont think we would get along". I have never understood truly what is going on, I know that women want me and see me as a sexual object, but then society has taught me, drummed it into me, that seeing women as mere sexual objects as being wrong, its a god damn double standard. Right there is even more stress.

Religion is good in a way that it allows people to fall into the idea of getting married, and staying together, otherwise I think we would all probably just fuck all the time. Hormones are cruel in that way and frankly I will be glad to be rid of the whole idea of mating someday, I mean its certianly pointless isnt it when we've reached the population limit for this planet.

If you think stress isnt playing a part in my shortened life expectancy, then think again.

Edited by Layberinthius, 25 August 2013 - 12:51 PM.

[Layberinthius]

But hey you know, maybe tomorrow will be a brighter day. Something newer might happen, a government might topple over.

You never know whats really gonna happen next in this crazy world.

Edited by Layberinthius, 25 August 2013 - 01:18 PM.

[tham]

Estrogen activates telomerase.

http://www.ncbi.nlm....pubmed/10606235



Greater endogenous estrogen exposure is associated with longer telomeres in
postmenopausal women at risk for cognitive decline.


'' ..... longer endogenous estrogen exposure was associated with greater TL
and with lower telomerase activity. Length of reproductive years was also
inversely associated with the combination of short TL and high telomerase.

'' Length of HT (hormone therapy) use was not associated with TL or telomerase
activity in this study. ''

'' ..... endogenous estrogens may be associated with deceleration of cellular aging. ''

http://www.ncbi.nlm....ubmed/20965155/



Effect of long-term hormone therapy on telomere length in postmenopausal women.

'' In conclusion, telomere lengths were longer in postmenopausal women who had
a history of long-term HT than in postmenopausal women without HT. Long-term
HT in postmenopausal women may alleviate telomere attrition. ''

http://www.ncbi.nlm....pubmed/16127770



Endothelial progenitor cell senescence - is there a role for estrogen ?

'' ..... aging or senescence constitutes a potential limitation to the ability of
endothelial progenitor cells (EPCs) to sustain ischemic tissue repair.

Conversely, estrogens have been shown to accelerate recovery of the
endothelium after vascular injury. ''



Life long endogenous estrogen exposure and later adulthood cognitive function
in a population of naturally postmenopausal women from Southern China: the
Guangzhou Biobank Cohort Study.

'' In a large cohort of naturally postmenopausal Chinese women proxies of greater
endogenous estrogen exposure were associated with better cognitive function. ''

http://www.ncbi.nlm....ubmed/21185655/



Estrogen deficiency leads to telomerase inhibition, telomere shortening and
reduced cell proliferation in the adrenal gland of mice.


'' .... estrogen deficiency causes inhibitions of TERT gene expression, telomerase
activity, telomere maintenance, and cell proliferation in the adrenal gland of
mice in vivo, suggesting that telomerase inhibition and telomere shortening
may mediate cell proliferation arrest in the adrenal gland, thus contributing to
estrogen deficiency-induced aging under physiological conditions. ''


http://www.ncbi.nlm....pubmed/18936784



Estrogen reduces cellular aging in human mesenchymal stem cells and chondrocytes.

'' In spite of reducing telomere shortening in aging MSCs and chondrocytes,
estrogen is not able to prevent somatic cells from replicative exhaustion and
from finally entering senescence. ''


http://www.ncbi.nlm....pubmed/21469181



Prevention of critical telomere shortening by oestradiol in human normal hepatic
cultured cells and carbon tetrachloride induced rat liver fibrosis.

'' Long term oestradiol administration markedly rescued the hepatic telomere
from extensive shortening in both male and female rats.

Oestrogen dependent transactivation of the hTERT gene is a new strategy
for slowing the progression of chronic liver disease. ''

http://www.ncbi.nlm....pubmed/15194652




Taller height of men shortens lifespan.

Tying it all together: telomeres, sexual size dimorphism
and the gender gap in life expectancy.


'' ..... an inverse correlation between mean telomere length and mortality in people
has been found. In this and two other studies, it was confirmed that males do
have shorter telomeres than females at the same age. This is almost certainly
a consequence of men being usually taller than women, although nobody has
done an investigation yet. Clearly, a larger body requires more cell doublings,
especially due to the ongoing regeneration of tissues over a lifetime. Accordingly,
the replicative history of male cells might be longer than that of female cells,
resulting in the exhaustion of the regeneration potential and the early onset of
age-associated diseases predominantly in large-bodied males. ''

'' Finally, I propose that the secular height increase over the last decades, of about
2.5 cm per generation in the western world, has to be blamed for the widening of
the gender gap in life expectancy. ''

http://www.ncbi.nlm....pubmed/14729022

[Avatar of Horus]

Estrogen ...

very good collection about it, thank you.
btw it is involved also in the bone marrow and thymus physiology.

[tham]

Oestrogen, telomerase, ovarian ageing and cancer.

'' .... oestrogen regulates cell proliferative fates by a mechanism of reprogramming
the size of telomeres (ends of chromosomes) in the oestrogen target cells.
This is achieved by upregulating the telomerase reverse transcriptase (TERT)
gene in a temporal and spatial manner.

'' ..... telomerase is a downstream target of oestrogen in oestrogen-dependent
reproductive ageing and neoplastic development. ''

http://www.ncbi.nlm....ubmed/19566833/

Edited by tham, 30 August 2013 - 12:28 AM.

[tham]

Telomere Dynamics and Longevity Gender Gap

'' Estrogen’s effects have two sides. Estrogen has a role in ameliorating oxidative
stresses, which known to increase telomere erosion rate. As the same time, it
stimulates the transcription of the gene encoding telomerase (Aviv et al., 2005).
The effects of estrogen on telomere dynamics may be attenuated or disappear
altogether in older women, but its premenopausal influence could set telomere
attrition at a trajectory that maintains longer telomeres in women throughout the
entire human life span. ''

http://biol1020.blog...ity-gender.html



The Longevity Gender Gap: Are Telomeres the Explanation ?

'' As expressed in WBCs, telomere length is highly heritable, inversely correlated
with age, longer in adult women than men, and yet equivalent in newborn boys
and girls.

Two factors may account for the longer telomeres that are observed
in women, namely estrogen and somatic cell selection.



Estrogen diminishes oxidative stress [for a review, see, whose cumulative burden
is fundamental to many theories of aging (see "The Two Faces of Oxygen").
Meanwhile, estrogen also stimulates the transcription of the gene encoding the
telomerase reverse transcriptase enzyme that adds telomere repeats (copied from
its integral RNA component) to chromosome ends, thereby curtailing or slowing
down the rate of telomere erosion (19, 20). Oxidative stress, conversely, escalates
telomere erosion [for a review, see (27)]. Theoretically, the ability of estrogen to
up-regulate telomerase and at the same time reduce oxidative stress could account
for the longer telomeres observed in women as compared with men. This effect of
estrogen on telomere dynamics may be attenuated or disappear altogether in older
women, but its premenopausal influence could set telomere attrition at a trajectory
that maintains longer telomeres in women throughout the entire human life span.
Such a possibility can readily be tested in the future by longitudinal studies of
telomere attrition rates in men versus women, and in premenopausal versus
postmenopausal women.


'' Skewed X-linked selection of somatic cells as a function of aging may be another
factor behind the longer telomeres observed in women as compared with men.
There is good evidence for gene variance on the X chromosome that strongly
influences telomere length. ''

'' It is anticipated that such selection would primarily be apparent in older women,
given that the critical telomere length associated with cellular senescence is more
likely to occur in a later phase of the human life span. Skewed X inactivation has
been observed primarily in women older than 60 years, supporting this tenet. ''

'' .... based on cross-sectional analyses, the rate of attrition of telomeres in WBCs
is about 30 base pairs (bp) per year. The mean telomere length in women is
approximately 240 bp longer than that in men, which equates to a disparity
between the sexes of about 8 "telomere years," roughly the same as the
observed gender gap in life expectancy. ''



Sign up to read the full free text :


http://sageke.scienc...ct/2005/23/pe16

http://sageke.scienc...ll/2005/23/pe16

[docTorpedo]

Taller height of men shortens lifespan.

Tying it all together: telomeres, sexual size dimorphism
and the gender gap in life expectancy.


'' ..... an inverse correlation between mean telomere length and mortality in people
has been found. In this and two other studies, it was confirmed that males do
have shorter telomeres than females at the same age. This is almost certainly
a consequence of men being usually taller than women, although nobody has
done an investigation yet. Clearly, a larger body requires more cell doublings,
especially due to the ongoing regeneration of tissues over a lifetime. Accordingly,
the replicative history of male cells might be longer than that of female cells,
resulting in the exhaustion of the regeneration potential and the early onset of
age-associated diseases predominantly in large-bodied males. ''

'' Finally, I propose that the secular height increase over the last decades, of about
2.5 cm per generation in the western world, has to be blamed for the widening of
the gender gap in life expectancy. ''

http://www.ncbi.nlm....pubmed/14729022

Yes, I have been scratching my head on speculations like women living longer because they loose iron due to menstrual cycles. There might be something to it, but it seems much more evident that its related to size given that smaller animals within the same species live longer than bigger ones: dogs, elephants etc. Bigger body, more cell divisions. I can't go into more detail because I'm a rookie at cell chemistry at the moment (working at it). This might also be my imagination but I seem to remember having read one place that there was a study done with men and woman of similar body size. The life expectancy was much closer when they took size into consideration.
Look at centenarians, they are all very tiny. Too bad for me because I'm a giant. But luckily I'm not the big boned type.

[pleb]

part post from earlier, it has been found. In this and two other studies, it was confirmed that males do
have shorter telomeres than females at the same age. This is almost certainly
a consequence of men being usually taller than women,

taking the last sentence i tend to disagree, whilst height does play a part i personally think oestrogen is the prime mover in women having longer lives on average as oestrogen is a known telemarase up regulator,

[Bogomoletz II]

Partly because your average man is more likely to engage in life-threatening behavior, but also because the mutations found in mtDNA are more harmful to males.

[PWAIN]

Partly because your average man is more likely to engage in life-threatening behavior, but also because the mutations found in mtDNA are more harmful to males.

So why is life expectancy for males still less at say 70? How many risk taking 70yo people do you think there are and why do they not die primarily from high risk activities? Why does it happen in other animal models?
Why does mtDNA only harm males - what makes us susceptible?

[Darryl]

It's approximately 73% lifestyle choices:

Life expectancy Men Women Difference
Californians 73.9 79.5 5.6
Adventists 81.2 83.9 2.7
Vegetarian Adventists 83.3 85.7 2.4
Healthy* Adventists 87.0 88.5 1.5

* never-smoking, vegetarian, exercise ≥ 3 times weekly, eat nuts ≥ 4 times weekly, BMI < 25.90 (males) or <25.20 (females).

[Bogomoletz II]

So why is life expectancy for males still less at say 70? How many risk taking 70yo people do you think there are and why do they not die primarily from high risk activities?

Think infectious diseases, for example. Stuff like that can reduce your life expectancy even if you no longer engage in that kind of behavior. Why would they die primarily from high-risk activities? There is statistical proof to the claim (1) that on practice men are less careful about their physical welfare and (2) that average male life expectancy suffers because of this. Darryl has provided some more data to back it up. But you know what? It doesn't matter, because I said “partly,” meaning that even if men were just as tame as women, the asymmetry would still be there, the 70-year-olds included.

Why does it happen in other animal models?

Males of most other animal taxa are also more likely than the females of the same taxa to do dangerous things (e.g., fighting with each other for mates)—partly because of that. But of course, humans are not the only ones with mtDNA.

Why does mtDNA only harm males - what makes us susceptible?

That's a good question. I don't know. The proximate mechanisms are, apparently, still unknown, but as for evolutionary explanations, the current consensus is that it's because mtDNA is passed to offspring from mothers only. Thus, those mutations that were harmful to the reproductive success of females were weeded out via natural selection, while the ones harmful to the reproductive success of males remained—or so they say. There's doubt, though: why would female reproductive success be affected considering that menopause makes females infertile long before aging kills them? Perhaps because of the reproductive advantage of being able to care for grandchildren, but I must admit, that's unconvincing. For the record, mtDNA has also mutations which interfere with male fertility while leaving female fertility unscathed.

There is a hypothesis saying that female life expectancy in mammals benefits from the fact that female mammals have two X chromosomes, so that they compensate for each other.

[Darryl]

One theory for lifespan expansion in the hominin lineage is "grandmothering", which posits that childcare and food gathering by post-menopausal grandmothers enabled their daughters to raise more children to reproductive maturity. This would provide a stronger selective pressure for female longevity than male. Given limited male involvement in child rearing in many hunter-gatherer societies, human male post-andropausal longevity may be a spandrel. If all of the longevity genes were on the sex-chromosomes, we might be living in very different world - matriarchal and matrilineal, with males as short-lived fondly remembered flings.

The leading exponent of the grandmothering theory is Kristen Hawkes of U. Utah.

Hawkes, Kristen, et al. "Grandmothering, menopause, and the evolution of human life histories." Proceedings of the National Academy of Sciences 95.3 (1998): 1336-1339.
Hawkes, K., and NG Blurton Jones. "Grandmothering and the evolution of Homo erectus." Journal of Human Evolution 36 (1999): 461-485.
Hawkes, Kristen, et al. "A reappraisal of grandmothering and natural selection."Proceedings of the Royal Society B: Biological Sciences 278.1714 (2011): 1936-1938.
Kim, Peter S., James E. Coxworth, and Kristen Hawkes. "Increased longevity evolves from grandmothering." Proceedings of the Royal Society B: Biological Sciences 279.1749 (2012): 4880-4884.

It makes more sense to me than any other explanation for the leap to longer post-reproductive lifespans about 2 million years ago.

Edited by Darryl, 19 January 2014 - 01:39 AM.

[maximum411]

A simple explanation is that men tend have a larger body size, and larger body size and higher IGF/mTOR/PI3K levels are associated with shorter lifespan (within a species). Men may live shorter lives than women for the same reason that Great Danes live shorter lives than Beagles, Ames Dwarf mice live longer lives than normal mice, and short people live longer lives than tall people.

[Maecenas]

A simple explanation is that men tend have a larger body size, and larger body size and higher IGF/mTOR/PI3K levels are associated with shorter lifespan (within a species). Men may live shorter lives than women for the same reason that Great Danes live shorter lives than Beagles, Ames Dwarf mice live longer lives than normal mice, and short people live longer lives than tall people.

I agree with you, but thats only a biological part of explanation. The second part is social and cultural. Men tend to have more unhealthy lifestyles in general. But in the highly developed countries the gap in life expectacy is not that big because here we have mostly biological mechanisms at work.

Edited by Maecenas, 02 February 2014 - 08:24 AM.