Female anatomy

[brightncheerful]

I'm not particularly knowledgeable about male anatomy, let alone female. I had hoped to get an answer from a consultant doctor yesterday but I don't think his reply really answered my question.

My questions are (1) why when the natural life-span is at least 100 years does the female biological clock have a relatively short a period of time for compared to the male ability to reproduce.

As I understand, the (female) ability to reproduce is at its peak when a woman's physical body systems, organs, etc are developed and still strong enough to cope with the stress and strain of giving birth. In other words, the biological clock has a natural cut-off point, after which the body doesn't have what it takes.

(2) what is the purpose of the female body after the cut-off point. Is it simply to age until worn out whereupon the body gives up and dies. Or are the post-reproductive years intended for something else? After all, assuming natural life-span at least 100 years, the cut-off point at 35 or thereabouts is only about one-third of that period of time.

The consultant's answer was to refer to the short life expectancy in Ancient Rome, which he said averaged 25-30. But according to the demographics, that it is not so apparently. “From around the first century BC onwards, the age of 60 or 65 was commonly mentioned as the threshold of old age". " So if they survived childhood, childbirth, and military service, Romans could expect to live as long as we do today."

The only thing i can think of for the female biological clock's cut off-point to be at a relatively young age compared to the male ability to produce which can continue for much longer is that perhaps nature doesn't intend males to be monogamous?

tia
BnC

[fisher]

Grandmothers are important for human evolution. Some articles here: https://www.smithsonianmag.com/science- ... -88972191/

and here: https://www.sciencealert.com/watch-why- ... s-survival

and here: https://www.theatlantic.com/health/arch ... rs/264039/

[pochisoldi]

You need to ask yourself the following questions
"Why do humans live for so long after they cease to have reproductive capacity"
"Why do human grandparents spend time helping to rear/bring up their childrens' children, when most/all other animals abandon their offspring as soon as they reach maturity if not earlier?"

[ReformedCharacter]

The only thing i can think of for the female biological clock's cut off-point to be at a relatively young age compared to the male ability to produce which can continue for much longer is that perhaps nature doesn't intend males to be monogamous?

tia
BnC

The risk of birth defects increases considerably with maternal age, for example Down Syndrome

At age 20, 1 in 1,441
At age 50, 1 in 44

https://en.wikipedia.org/wiki/Advanced_ ... th_defects

The risk of Autism and other defects also increases with maternal age. AFAIK it has become recognised more recently that paternal age also carries increased risk of birth defects, eg Autism - but this effect appears to be less pronounced than maternal age.

RC

[dionaeamuscipula]

My questions are (1) why when the natural life-span is at least 100 years does the female biological clock have a relatively short a period of time for compared to the male ability to reproduce.

Who says the natural life span is at least 100? Even girls born today are only about 35% likely to reach 100.

Women have their maximum potential egg production in place at birth. It then falls away over time through natural processes, such that they are done (less than 1,000 left) by about 50 on average. Men can fully replace ejaculate in about 3 - 5 days, and are back to maximum. Sperm production will reduce over time, but it still only takes one sperm.

So it comes down to the difference in reproductive processes.

DM

[melonfool]

(2) what is the purpose of the female body after the cut-off point. Is it simply to age until worn out whereupon the body gives up and dies. Or are the post-reproductive years intended for something else? After all, assuming natural life-span at least 100 years, the cut-off point at 35 or thereabouts is only about one-third of that period of time.

tia
BnC

a) women don't begin to be able to reproduce until about age 14, so it's not a third on your reckoning. More a fifth.

b) women can in fact reproduce until, around age 50 - age is not the issue though, women have a finite number of eggs when they are born and it is when these run out their reproductive years end.

c) what is the point of impotent men then?

d) it's not really a 'DAK' is it? I doubt anyone can ever know for sure.

Mel

[XFool]

The only thing i can think of for the female biological clock's cut off-point to be at a relatively young age compared to the male ability to produce which can continue for much longer is that perhaps nature doesn't intend males to be monogamous?

Ahem! Just like to point out that "nature" doesn't "intend" anything at all. Nature doesn't, AFAIK, have intentions.

[UncleEbenezer]

Ask a question like that, and you're going to get replies either stating or purporting to refute pop science and the obvious. So here goes.

Simple answer to the difference: the respective investment of the sexes in reproduction. Biologically speaking, a man can reproduce at the cost of a few energetic minutes, so it's no skin off his nose to stay fertile as he ages. Whereas a woman has a much more physically demanding role, and as she loses the vigour of youth, her chances of surviving - let alone reproducing successfully - diminish.

Today's statistics are distorted from what biology would give us, by the societal pressure that discourages breeding while young, and by modern healthcare that serves to take away most of the risk. And on the male side, by the protection society offers to an old roue against the wrath of the alpha male and against economic destitution. The male has a big reduction in sex drive (you distantly recollect how intense it all was in your 'teens?), which is nature's way of saying he's no longer fit to be alpha male and discretion would be the better part of valour unless a really exceptional opportunity arises.

Evidence? Well, anecdotally I have certainly found as I've got older, I'm no longer randomly threatened by gangs of drunken yobs. Maybe society has changed, but I suspect at least some of that comes from no longer being perceived by them as a prospective alpha male who needs to be actively put down lest he become a rival.

[bungeejumper]

“From around the first century BC onwards, the age of 60 or 65 was commonly mentioned as the threshold of old age". " So if they survived childhood, childbirth, and military service, Romans could expect to live as long as we do today."

Hmmm, that sounds like a case of history being written selectively by the rulers, the educated and the other obvious survivors. I'd doubt that slaves, daily workmen or low-level military grunts would have been included in that 60-65 demographic. It was also quite common to starve to death when you lost your teeth.

BJ

[bungeejumper]

a) women don't begin to be able to reproduce until about age 14, so it's not a third on your reckoning. More a fifth.

That, in itself, is a biological oddity. I'm told that during the 19th century the age of first menstruation went up from 13 to 17 or 18, even though diets were improving for most of that time. It looks as though societal pressures were somehow influencing "nature".

b) women can in fact reproduce until, around age 50 - age is not the issue though, women have a finite number of eggs when they are born and it is when these run out their reproductive years end.

Yes, but. The rising risk of birth abnormalities beyond 40 or so is a pretty fair mirror to the corresponding fact that men's sperm deteriorates steadily in quality from age 25 or thereabouts. And that all kinds of genetic errors creep in as we age - errors that our younger bodies would have killed off at source, but which can overwhelm as they become more numerous. Cancer being the best example.

The reason why a defective sperm doesn't often get through to the egg is that it generally doesn't swim fast enough, and it's up against 100 million healthier competitors. Whereas the egg, being the only one there at the time, is going to get fertilised whatever its condition.

c) what is the point of impotent men then?

They make better Supreme Court judges?

BJ

[wheypat]

I think the issue is the modern life. A human being is proably designed to live 30 to 35 years. But modern life styles, access to food, shelter, medicine etc. extends the life span considerably.

Cats for example, in the wild the lifespan is ~2 years. My moggy is now approaching his 20th birthday as he has a constant supply of food, he gets wormed and defleaed (and these days a monthy shot of anti-biotics). Were as the feral cat does not.

So women are probably designed to be fertile up to their deaths. Just we've managed to extend lifespans.

https://en.wikipedia.org/wiki/Life_expectancy

[bungeejumper]

A propos of nothing, I just checked my memory about one particular randy old goat. The guitarist Andres Segovia, after a lifetime of extramarital affairs, married a young slip of a girl in 1962 (his third wife) and became a father for the first time at the age of 77. Respect.

BJ

[wheypat]

A propos of nothing, I just checked my memory about one particular randy old goat. The guitarist Andres Segovia, after a lifetime of extramarital affairs, married a young slip of a girl in 1962 (his third wife) and became a father for the first time at the age of 77. Respect.

BJ

Try Mick Jagger - at 73 became a father for the 8th time. Jagger is now the first recorded person to have a child younger than a great-grandchild.

[WorldCupWilly]

bungeejumper wrote: A propos of nothing, I just checked my memory about one particular randy old goat. The guitarist Andres Segovia, after a lifetime of extramarital affairs, married a young slip of a girl in 1962 (his third wife) and became a father for the first time at the age of 77. Respect.

Yes but was it his? that predates home DNA tests and the Jeremy Kyle Show.

WCW

[bungeejumper]

Yes but was it his? that predates home DNA tests and the Jeremy Kyle Show.

Looks quite like him - has the same distinctive nose, etc. But with a luxuriant moustache. Well fair enough, he is 48 now.

For the record, when the happy couple tied the knot she was 22 and he was 69. And he lived to be 94. Not too bad.

BJ

[melonfool]

Yes but was it his? that predates home DNA tests and the Jeremy Kyle Show.

Looks quite like him - has the same distinctive nose, etc. But with a luxuriant moustache. Well fair enough, he is 48 now.

For the record, when the happy couple tied the knot she was 22 and he was 69. And he lived to be 94. Not too bad.

BJ

Bet she was annoyed he lived that long!

Mel

[UncleEbenezer]

I think the issue is the modern life. A human being is proably designed to live 30 to 35 years.

A human is designed for no such thing. When someone tells you about averages, don't get distracted into thinking of them as norms: average human lifespan has risen in modern times not because a healthy adult can expect to a much older age, but rather because the vast majority now survive into adulthood and the average isn't pulled down by a majority dying in infancy.

The ancient greeks had lifespans not unlike our own.

[bungeejumper]

Average human lifespan has risen in modern times not because a healthy adult can expect to a much older age, but rather because the vast majority now survive into adulthood and the average isn't pulled down by a majority dying in infancy.

The ancient greeks had lifespans not unlike our own.

So your inference is that the ending of the heavy juvenile deaths in the past has exerted most of the change in today's general life expectancy? And therefore that life expectancy for (say) a 25 year old is broadly the same as it was 3,000 years ago? And that medical advances haven't played a significant role in the extension of life expectations?

Oooh, come on, pull the other one. Got any refs or sources for this theory? (Genuine question. I'm interested.)

BJ

[UncleEbenezer]

Average human lifespan has risen in modern times not because a healthy adult can expect to a much older age, but rather because the vast majority now survive into adulthood and the average isn't pulled down by a majority dying in infancy.

The ancient greeks had lifespans not unlike our own.

So your inference is that the ending of the heavy juvenile deaths in the past has exerted most of the change in today's general life expectancy?

In the context of short lifespans cited as historic norms, yes.

And therefore that life expectancy for (say) a 25 year old is broadly the same as it was 3,000 years ago? And that medical advances haven't played a significant role in the extension of life expectations?

Up to a point. But of course there you need to distinguish between a 25-year-old leading a hard hand-to-mouth existence and one living in easier conditions, and such things. My observation really applies to the well-off, of whom there are of course far more today than in the past. Modern medicine may have added a decade to your biblical three-score-years-and-ten, but not the dramatic difference implied by a claim we all died at 35.

As for sources (apart from that biblical one), the greeks' own writing tells us octogenarians were not unusual, and my favourite playwright (Σοφοκλῆς) lived into his 90s.

[dionaeamuscipula]

Average human lifespan has risen in modern times not because a healthy adult can expect to a much older age, but rather because the vast majority now survive into adulthood and the average isn't pulled down by a majority dying in infancy.

The ancient greeks had lifespans not unlike our own.

So your inference is that the ending of the heavy juvenile deaths in the past has exerted most of the change in today's general life expectancy? And therefore that life expectancy for (say) a 25 year old is broadly the same as it was 3,000 years ago? And that medical advances haven't played a significant role in the extension of life expectations?

Oooh, come on, pull the other one. Got any refs or sources for this theory? (Genuine question. I'm interested.)

BJ

There are a number of graphs in this article which consider this point.

https://www.ons.gov.uk/peoplepopulation ... 2015-09-09

DM

(Of course some people will believe that militant Lifeteers in the ONS have manipulated the data to show this result which largely backs up UE's assertion)