What is the evolutionary reason we live, on average, 40 years longer than our reproductive ability?

[justanotherneighinparadise]

I was pondering this whilst putting in my make up 🤣

If the sole reason for existence is to reproduce, why do we generally live forty years or so later than our eggs viability?

The only thing I’ve come up with is to be old enough to raise our own children to adulthood and then perhaps be the matriarch of a troop and help raise grandchildren etc?

Looking after the GC whilst the DC hunt and gather I presume.

It’s not evolution - it’s (largely) modern medicine! Until about a hundred years ago women frequently died in their mid-40s, so the menopause is a modern ‘invention’ too. Essentially once we’ve stopped being useful from a reproductive point of view we’re just gradually wearing out (cheerful thought)

Also a long time ago, we didn't live 40 years past our reproductive age. Advances in medicine, living conditions, public health mean that average life expectancy has increased massively. Previously we would have been a lucky to live past infancy, and exceptionally lucky to live to around 40

It's a reward for raising dc. Bit bloody peace!

We're definitely not meant to live as long as we do and would have been quite likely to be dead by 40.

Science is why we live longer now. Not evolution.

I thought there was some stuff about sleep patterns, how young adults are late risers and older people tend to be up early, so we can share the childcare.

Have people died young until recently? The Bible has three score years and ten (70) as an "expected" lifespan, although of course there were early deaths too.

But we have the capacity to live until we’re 100 seemingly. Modern medicine and living conditions dictate that many of us are now more likely to hit old age. I just wonder what the point of it is? I can only think it must be to do with helping to raise future generations.

To quote NewsQuiz some years back,
‘Science shows that once women were no longer able to bear their own children, they would hand them to granny until she couldn’t stand them either.’

@FlyingSquid

To quote NewsQuiz some years back, ‘Science shows that once women were no longer able to bear their own children, they would hand them to granny until she couldn’t stand them either.’

🤣

People dont understand maths!

When we say the average life expectancy was ‘40’ in medieval times it doesn’t mean people does age 40! Lots of babies didn’t make it to 1 or 5. That dramatically brings down the average life expectancy. Once people got to adulthood they would expect to live to 60+.

Older women were crucial in child rearing as younger women were out hunting and gathering (which was more divided by age than sex).

I don’t think there is an evolutionary point as I don’t think we were supposed to live that much longer. Modern medicine and living has meant that we do.

A life expectancy of 30, for example,doesn't mean older people are a rarity. Average life expectancy is normally quoted from birth and early childhood is very risky and drags that average figure way down. At each stage you survive your individual expected life span remaining increases.

Childbirth is also very risky and can be more dangerous the older you get. From an evolutionary perspective having the menopause makes sense as it would increase the life expectancy of women who made it that far in the first place. If a daughter then died in childbirth you could raise her children which would increase their chances of surviving to adulthood. With women we know who are children are so can be sure it is our genetic line which is benefiting.

IIRC the menopause is a bit of a puzzle anyway, but the above would make sense, especially as to how something which stops the ability to reproduce could be selected for.

Its been a long time since I studied evolution and this is totally off the top of my head thinking but from my limited knowledge I could see why it makes sense! Fully prepared to be totally wrong though .

Yes I think community. Helping to raise the children, caring for the sick, cooking, still hunting/gathering etc. I think we are really a much more community-minded species but modern times has us all in our own units and homes. But I'm sure I read once that we weren't like this until more modern times.

Without medical science most people wouldn't live for 40 years after menopause, but they probably would live to be 60-70. Human children need a parent for a long time - at least 12-15 years.

Menopause gives you enough time to raise your youngest child and help them with their children's early years before you die. If you died at 45-50 your youngest would be a toddler and unlikely to survive.

I agree with PPs comments about medicine , knowledge of disease and the point about life expectancy. There is another important factor, knowledge.
If we ignore the modern era, the various forms of Homo Sapien have shown an increase in brain size, and specimens past child-rearing age (female at least, males seem to continue being reproductive until death) are not uncommon. It could well be they carried the clan's information about location of food, strategies to deal with unusual events (flood, drought etc). Those groups that supported the elderly would have an advantage over those that didn't , so evolution preserved that trait.

As pps have said, much to do with science and lifestyle. Society tends towards far gentler jobs now, so fewer deaths down the mine, on the railway etc and if you have an illness or occupational accident for example, you can be saved. I think there is also the expectation that age needs to be prolonged at all costs. You see posters on MN reporting the death of a loved one as 'too soon' or they were 'too young' but the deceased was actually in their 70s. We, rightly or wrongly, insist that life is preserved and because everyone knows someone who did yoga and rode a motorbike at 108 then old age is a marvellous thing.

Off topic we are keeping sad, ill, mad people alive. Resources should go to those who still have a life to enjoy. I want to choose when I go and not be a burden to family or society.

When we say ‘modern medicine’, how modern are we talking? Plenty of people lived to very old ages in the past.

People dont understand maths!

When we say the average life expectancy was ‘40’ in medieval times it doesn’t mean people does age 40

Older women were crucial in child rearing as younger women were out hunting and gathering

I think some people don't have much of a grasp of history either!

In medieval times 40% of people died by the time they were five, once you made it out of childhood you could expect to live anywhere up to 70 years. We are a rare breed in that we exist long after our fertile years.

Just because the average life span used to be 30-40 doesn't mean that people regularly keeled over in their 30s. Actually most people would have died in infancy or at around 60.

One evolutionary advantage for women to stop reproducing a couple of decades before they're expected to die is that young, motherless children would have been less likely to survive to reproductive age so it's more advantageous to switch to helping to raise your children's children.

The other reason is that women are born with all of their eggs and so birth defects increase with the mother's (i.e. the egg's) age.

It was more like 20 years than 40. I’m guessing partly passing on learned wisdom, partly extended group workforce including childcare, food prep, medicines etc.

Elizabeth 1st died at 69.

As others have said, whilst average lifespan may have been lower, if you survived adulthood and didn't die in childbirth, you could still be expected to go on well past menopause, even before modern medicine.

Survived to adulthood...