How did we evolve to live up to elderly life?

[soon2bepro]

First of all, if you don't believe in, or don't understand evolution as a reasonable scientific theory, REFRAIN from posting in this thread. Please.

Women can't procreate after a certain age. Most men can't either, not because of infertility but because of other reasons. So how did we evolve to the point where some of us naturally live so many years? What's the darwinian explanation for elderly life?

Maybe because elders are often wiser so they help others survive? But old people are often not wiser. A wise man is often wise most of his life, not just when he's reached old age.

Maybe it has something to do with wise men having more time to spread their knowledge.

What do you people think?

[chezlaw]

A popular explanation (no idea of any evidence) is grandparenst help look after the kids. Makes intuitive sense to me.

[David Steele]

It is my impression that most did not live to the point you are talking about before modern medical developments.

D.

[eurythmech]

Makes sense that you don't die until your kids are old enough to take care of themselves/each other?

[Prodigy54321]

I think that the main reason why people live a good amount of time after the age that they tend to stop procreating is that we have developed a tendency to take care of them..without assistance in the form of advances in medicine and personal care for them, they would not live so long after the age that they tend to stop procreating.

Dawkins I think explained it well in "The Selfish Gene"..he explained old age as basically the accumulation of harmful tendencies such as tendencies to develop diseases that are only triggered late in life, that is after the age that people tend to stop procreating.

the reason why this is true is obvious..late life harmful tendencies are taken out of the gene population much less so than early life harmful tendencies because older people already had a chance to procreate...Dawkins even commented briefly that he suspected that you could make humans live much longer than they do now if we abided by a rule that we are not allowed to have children before a certain age.

[alphatmw]

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It is my impression that most did not live to the point you are talking about before modern medical developments.

D.

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[soon2bepro]

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It is my impression that most did not live to the point you are talking about before modern medical developments.

D.

[/ QUOTE ]

But some did. And they weren't rare cases.

[chezlaw]

[ QUOTE ]
[ QUOTE ]
It is my impression that most did not live to the point you are talking about before modern medical developments.

D.

[/ QUOTE ]

But some did. And they weren't rare cases.

[/ QUOTE ]
To some extent that's just statistical, if there's an increasing probability of dieing each year (above some age threshold) then many will live longer than others.

I don't know if there are any useful simulations comparing 1) every agent is killed off when the offspring are adult and 2) dieing gradually over time and caring for the grandchildren.

Isn't is just a question of which makes better use of resources? and if resources are plentiful then the extra nuturing is very cheap.

chez

[madnak]

Older people (particularly women) probably played a major social role in early societies. This involved raising children, managing the community, and sharing knowledge (the trait that was ultimately responsible for our success as a species). This became especially true as communities became more organized and ideas of authority developed, and as different peoples began to collect larger and larger amount of information about seasons, plants, and animals. Also, most of the food for early humans was obtained through gathering, and humans are competent gatherers into old age.

With regard to the idea that nobody lived long until modern times, that is a cultural myth. It probably stems from the fact that in early civilized cultures life expectancy was often very low (due primarily to infant mortality rates) and that such cultures had a strong tendency to show widespread malnourishment. This was apparently unique to civilized cultures, however - civilization arose in areas where the natural resources became scarce due to climate change. The development of irrigation was basically an act of desperation, as populations increased and arable land decreased. It's likely that humans were living to 6' tall or more and to 60-80 years of age in the natural environments of the Paleolithic.

[danlux]

Dr. Drew said that humans were only supposed to live to be about 40 years old naturally. I trust Dr. Drew.

[SitNHit]

Maybe a creator designed it that way, ooops, sry...

[Phil153]

I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[vhawk01]

[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[/ QUOTE ]

But an important part of that would have to be that designing bodies with this extra vitality comes at no cost over designing less vital bodies. That may very well be true: the adaptations that were selected for in other niches and for other conflicts might just have, as a side effect, an increase in 'vitality.'

But its not exactly obvious that this is the case. It seems, perhaps superficially, that building a body that is capable of living 120 years takes more resources than building one that lasts 40 years, and these resources are wasteful, unless you can posit some benefit to grandparents. So, we've either got to explain how the resources required are identical or explain the benefit that offsets the costs. Madnak and others are trying to do the latter, and it seems like you are saying the former?

[chezlaw]

[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[/ QUOTE ]
That might be true but only if there was no significant evolutionary advantage either way.

chez

[abridge]

Sharing wisdom, increasing general happiness of others, taking care of children all serve a purpose in society.

Depends on the grandparents, of course. Mine are late 60's/early 70's and still kickin' - and I'd say they produce a lot of benefit for the individuals that are around them.

Evolutionarily speaking, old people increase the ability for society to produce rational, thinking, and adaptable, well-rounded beings. Using the same perspective from the "technology as a 7th kingdom" guy, older people + technology both aid in creating a good environment for growth in this way.

[Phil153]

[ QUOTE ]
[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[/ QUOTE ]

But an important part of that would have to be that designing bodies with this extra vitality comes at no cost over designing less vital bodies. That may very well be true: the adaptations that were selected for in other niches and for other conflicts might just have, as a side effect, an increase in 'vitality.'

But its not exactly obvious that this is the case. It seems, perhaps superficially, that building a body that is capable of living 120 years takes more resources than building one that lasts 40 years, and these resources are wasteful, unless you can posit some benefit to grandparents. So, we've either got to explain how the resources required are identical or explain the benefit that offsets the costs. Madnak and others are trying to do the latter, and it seems like you are saying the former?

[/ QUOTE ]
Vitality and spare energy in youth is a huge advantage in survival and sexual selection. Immune systems that are capable of warding off more disease in youth will no doubt enable a person to better avoid disease in older age. Heart muscles that can take prolonged strain in youth would no doubt outlast those that can't, all things being equal.

There's also the fact that the longer lifespans mean more opportunities for reproduction. Even men of Sklansky's age occasionally get one away in a healthy female of reproductive age. Perhaps female longevity is piggybacked on the genes that cause male longevity? Who knows

Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.

I have no doubt that there are species of non or less social animals who would live past viable breeding age if kept stimulated.

[ QUOTE ]
That might be true but only if there was no significant evolutionary advantage either way.

chez

[/ QUOTE ]
Many human traits are no doubt byproducts of other mechanisms. For example, our strong social bonds may well be a byproduct of some mutation that caused longer periods of infancy and weaker offspring. Or a grouping of traits causing more gray matter and longer brain development times. The cause of social behavior may not have been the direct advantages it provided to groups, but rather of byproduct of more effective rearing patterns, such as the development of bonding and communication systems between individual mothers and children, that allowed a greater development of intelligence and knowledge in those children. Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage.

In fact, this is one of my pet peeves when the people (including experts) talk about evolution. The authority you guys give to your evolutionary interpretations of human behavior is amazing, and on par with a lot of religious thought. You simply have no freaking clue how these things developed (and neither do I). You apply a highly oversimplified version of natural selection to explain what you observe in everyday, and then treat the result as obviously true. It's almost like sympathetic magic.

[tolbiny]

[ QUOTE ]
[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[/ QUOTE ]

But an important part of that would have to be that designing bodies with this extra vitality comes at no cost over designing less vital bodies. That may very well be true: the adaptations that were selected for in other niches and for other conflicts might just have, as a side effect, an increase in 'vitality.'

But its not exactly obvious that this is the case. It seems, perhaps superficially, that building a body that is capable of living 120 years takes more resources than building one that lasts 40 years, and these resources are wasteful, unless you can posit some benefit to grandparents. So, we've either got to explain how the resources required are identical or explain the benefit that offsets the costs. Madnak and others are trying to do the latter, and it seems like you are saying the former?

[/ QUOTE ]

To begin with all lives are not lived the same. Age isn't just the adding of years, its the adding of stresses (physical, emotional, psychological). If you were able to live 40-50 years just fine under average conditions but no more your line would be wiped out when conditions were harsher and you had to do more work to survive and procreate each year. In poker terms your Risk of Ruin would be quite high if you were incapeable of living past a certain age.

[vhawk01]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

The man reason we live to an old age because our bodies have enough vitality in youth to last for a number of years after our prime. No different to a car whose components generally work for a 10 year lifespan but is still going after 40.

[/ QUOTE ]

But an important part of that would have to be that designing bodies with this extra vitality comes at no cost over designing less vital bodies. That may very well be true: the adaptations that were selected for in other niches and for other conflicts might just have, as a side effect, an increase in 'vitality.'

But its not exactly obvious that this is the case. It seems, perhaps superficially, that building a body that is capable of living 120 years takes more resources than building one that lasts 40 years, and these resources are wasteful, unless you can posit some benefit to grandparents. So, we've either got to explain how the resources required are identical or explain the benefit that offsets the costs. Madnak and others are trying to do the latter, and it seems like you are saying the former?

[/ QUOTE ]
Vitality and spare energy in youth is a huge advantage in survival and sexual selection. Immune systems that are capable of warding off more disease in youth will no doubt enable a person to better avoid disease in older age. Heart muscles that can take prolonged strain in youth would no doubt outlast those that can't, all things being equal.

There's also the fact that the longer lifespans mean more opportunities for reproduction. Even men of Sklansky's age occasionally get one away in a healthy female of reproductive age. Perhaps female longevity is piggybacked on the genes that cause male longevity? Who knows

Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.

I have no doubt that there are species of non or less social animals who would live past viable breeding age if kept stimulated.

[ QUOTE ]
That might be true but only if there was no significant evolutionary advantage either way.

chez

[/ QUOTE ]
Many human traits are no doubt byproducts of other mechanisms. For example, our strong social bonds may well be a byproduct of some mutation that caused longer periods of infancy and weaker offspring. Or a grouping of traits causing more gray matter and longer brain development times. The cause of social behavior may not have been the direct advantages it provided to groups, but rather of byproduct of more effect rearing patterns, such as the development of intelligence and knowledge enhancing bonds between individual mothers and children. Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage.

[/ QUOTE ]

I pretty much agree with you, but I wanted to answer one thing. In regards to 'why would we be programmed to die at age 40,' while this probably isn't the case, it certainly isn't impossible. When you look at selection as effecting the gene level, having non-replicators sitting around, sucking up resources, would be something that would be selected against. So, if you had a trait for 'dying at age 40,' it wouldn't confer any specific reproductive advantage, but also no disadvantage, and if it was able to become more prevalent in the species, it would start to confer an advantage. A society where everyone dies after reproducing wastes less resources.

Of course, in humans, our adolescence is so extended that dying 'right after reproducing' isn't really beneficial. But look at flies. Doesn't it make sense to view them as 'designed' to die shortly after reproduction?

[chezlaw]

[ QUOTE ]
Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage

[/ QUOTE ]
No but if a trait provides a significant evolutionary advantage then we would likely have it.

[ QUOTE ]
Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.


[/ QUOTE ] I think that may be incorrect. Maybe its some myth but don't some cells stop reproducing after a number of generations?

chez

[Phil153]

[ QUOTE ]
[ QUOTE ]
Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage

[/ QUOTE ]
No but if a trait provides a significant evolutionary advantage then we would likely have it.

[/ QUOTE ]
Nonsense.



[ QUOTE ]
Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.


[/ QUOTE ] I think that may be incorrect. Maybe its some myth but don't some cells stop reproducing after a number of generations?

chez

[/ QUOTE ]
From what I understand the jury is very much out. There are a heap of competing theories on why most animal cells age. I'm in the "accumulated errors" camp. RDuke?

[vhawk01]

[ QUOTE ]
[ QUOTE ]
Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage

[/ QUOTE ]
No but if a trait provides a significant evolutionary advantage then we would likely have it.

[ QUOTE ]
Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.


[/ QUOTE ] I think that may be incorrect. Maybe its some myth but don't some cells stop reproducing after a number of generations?

chez

[/ QUOTE ]

There are large repeat sequences of DNA on the end of chromosomes called telomeres. These are more or less nonsense, junk sequences, and their function is to serve as protective caps. DNA replication causes a physical problem on linear chromosomes (which we have, compared to bacterial chromosomes) near the ends, because the replication machinery runs out of room. So, a little bit is lost off the end of our chromosomes each time they are replicated. If it wasn't for these telomeres, we would be losing important info. Over the course of many replications, we start to lose these telomeres, and then our cells die. I don't think this has been explained to full detail, but I am almost certain that short telomeres leads to signaling which leads to programmed cell death. For example, cloned sheep and other animals have shorter than normal telomeres, making them essentially artificially old. This leads to lots of cell death and early death of the organism.

The above is for somatic cells only.

[chezlaw]

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Quote:
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Quote:
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Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage


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No but if a trait provides a significant evolutionary advantage then we would likely have it.


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Nonsense.

[/ QUOTE ]
So if there was a big advantage for a species with longer living members you wouldn't expect them to evolve longer living members?

chez

[Phil153]

chez,

Yes, we would likely have it, but only because there is a mechanism and variation already in place to act on. In the general case, your comment:
[ QUOTE ]
No but if a trait provides a significant evolutionary advantage then we would likely have it.

[/ QUOTE ]
is completely wrong. For one, the "best" trait doesn't miraculously rise to be the dominant one in a species. There has to be a mechanism for the relevant genes and reproductive factors to express themselves so that natural selection can act. "Best" traits are only relevant to a specific environment, and often a fairly narrow one. Environments change. The timespan has to be sufficient. And even then, a whole lot of luck is needed for that trait to become dominant. And it may compete against other traits.

For example, it would be beneficial if monkeys developed larger and large brains and higher language. Extremely beneficial. It's a huge evolutionary advantage for something with fine dexterity and socially based mating rituals to be smarter. And yet, most of them haven't developed large or more intelligent brains in the last few million years. Only humans have jumped that gap - and probably through nothing more than a fluke of nature and timing.

Anyway, this is tangetial. The point I was making earlier is that the existence of a trait does not mean it came about through selection of that particular trait. In some cases, it's not even likely. Evolution and the historical nuances that lead to a particular human trait are so damn complex we can't make any intelligent statements without a deep understanding of the issue.

[chezlaw]

[ QUOTE ]
chez,

Yes, we would likely have it, but only because there is a mechanism and variation already in place to act on. In the general case, your comment:

Quote:
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No but if a trait provides a significant evolutionary advantage then we would likely have it.


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is completely wrong. For one, traits don't miraculously appear. There has to be a mechanism for the relevant genes and reproductive factors to express themselves so that natural selection can act. And then a whole lot of luck is needed for that trait to become dominant. Just as importantly, it may compete against other traits.

[/ QUOTE ]
I agree with what you said but its not a rebuttal of what I said which you actually seem to agree with.

So I'm a bit confused and think you that maybe you are'nt reading 'significant advantage' and 'likely' in the way I intended.

chez

[almostbusto]

i think a lot of people's answers are completely ignoring the fact that other species live passed fertility as well. including species that don't raise they young in such an active manner. (if i am dead wrong on this then correct me)


spiders, at least some kinds, die right after laying their eggs, its seems there is a whole continuum of species between humans and spiders.

i doubt those 100 year old tortoises in the Galapagos are making babies at that age. i haven't heard any stories of 14 year old cats having babies either. and i doubt either species concerns itself with grandparenting much.

[chezlaw]

[ QUOTE ]
i think a lot of people's answers are completely ignoring the fact that other species live passed fertility as well. including species that don't raise they young in such an active manner. (if i am dead wrong on this then correct me)

[/ QUOTE ] Its not a matter of dead wrong or ignoring this type of stuff. If past a certain age provides no benefit at all then its clearly not an evolved trait that takes advantage of anything. If it also provides no disadvantage perhaps because during this period of time there was no shortage of resources then there would be no evolutionary advantage in dying young.

chez

[furyshade]

most living things don't exist for the soul purpose of reproducing then dying, things like arachnids and insects often need to be eaten by young after laying eggs so the young can mature, but more evolved things tend to strive to live as long as possible, we are programmed to do this, one of the first limbic brain functions is "don't die"

[Miss Pink]

Thanks. Hey, I guess they're right. Senior citizens, although slow and dangerous behind the wheel, can still serve a purpose. I'll be right back. Don't you go dying on me!

[Borknagar]

I hear a lot of good things here, but I´m still missing something.

The biggest reason why we can live so long is because of the toilet. Before it was invented people would take dumps in the river and also use that water to drink from and cook with. Our sanitary system is the main reason why we can live so much longer than people hundreds of years ago.

If you don´t believe it, then imagine what LA or New York would be like without toilets.

[madnak]

[ QUOTE ]
I hear a lot of good things here, but I´m still missing something.

The biggest reason why we can live so long is because of the toilet. Before it was invented people would take dumps in the river and also use that water to drink from and cook with. Our sanitary system is the main reason why we can live so much longer than people hundreds of years ago.

If you don´t believe it, then imagine what LA or New York would be like without toilets.

[/ QUOTE ]

Stable population centers are a recent development. Through most of human history, small tribes moved across the land hunting and gathering, and the total population was rather small.

[madnak]

[ QUOTE ]
Vitality and spare energy in youth is a huge advantage in survival and sexual selection. Immune systems that are capable of warding off more disease in youth will no doubt enable a person to better avoid disease in older age. Heart muscles that can take prolonged strain in youth would no doubt outlast those that can't, all things being equal.

[/ QUOTE ]

This is definitely not true across the board. Part of the reason women live longer than men is because men are built to accept more stress - this isn't a trait that helps us live longer. But it gets much more complicated than that. At the least, long lifespans have clear costs - older people need to be supported by the community, etc. Therefore, the consideration of benefits is perfectly relevant.

[ QUOTE ]
There's also the fact that the longer lifespans mean more opportunities for reproduction. Even men of Sklansky's age occasionally get one away in a healthy female of reproductive age. Perhaps female longevity is piggybacked on the genes that cause male longevity? Who knows

[/ QUOTE ]

But women appear built to live longer than men. A hypothesis must be consistent with that fact in order to be valid. Still, this is another valid reason why long lifespans may have been selected for - I thought you were arguing that such mechanisms were irrelevant?

[ QUOTE ]
Besides, why would evolution design us to suddenly die when we're 40? It makes no sense. From what I've seen bodies carry on for as long as it can before they wear out.

[/ QUOTE ]

It's hard to know. There are plenty of viable hypotheses, but I don't think any really stand out.

[ QUOTE ]
Many human traits are no doubt byproducts of other mechanisms. For example, our strong social bonds may well be a byproduct of some mutation that caused longer periods of infancy and weaker offspring. Or a grouping of traits causing more gray matter and longer brain development times. The cause of social behavior may not have been the direct advantages it provided to groups, but rather of byproduct of more effective rearing patterns, such as the development of bonding and communication systems between individual mothers and children, that allowed a greater development of intelligence and knowledge in those children. Just because we have some trait doesn't mean that that specific trait provided an evolutionary advantage.

[/ QUOTE ]

That's true. I think a hypothesis that longevity is a secondary trait is reasonable. But that doesn't mean we should reject the alternatives out of hand.

[ QUOTE ]
In fact, this is one of my pet peeves when the people (including experts) talk about evolution. The authority you guys give to your evolutionary interpretations of human behavior is amazing, and on par with a lot of religious thought. You simply have no freaking clue how these things developed (and neither do I). You apply a highly oversimplified version of natural selection to explain what you observe in everyday, and then treat the result as obviously true. It's almost like sympathetic magic.

[/ QUOTE ]

I don't think that's true. Almost everyone who's familiar with evolution is aware that most of it is speculation to some degree. But there are prevailing hypotheses that are consistent with, for example, our natural history. In some cases (especially regarding death itself) they are tenuous, in other cases (the negative influences of civilization) they're much stronger. But whatever they are, it seems to me that they're very relevant to this thread.

[madnak]

[ QUOTE ]
For example, it would be beneficial if monkeys developed larger and large brains and higher language. Extremely beneficial. It's a huge evolutionary advantage for something with fine dexterity and socially based mating rituals to be smarter. And yet, most of them haven't developed large or more intelligent brains in the last few million years. Only humans have jumped that gap - and probably through nothing more than a fluke of nature and timing.

[/ QUOTE ]

While your general point here is correct, this is a bad example. It's very unlikely that larger brains would benefit monkeys (at least in the "short term" of thousands of years). Looking at the benefits of a trait without looking at the costs is unjustifiable. Large brains are extremely costly.

Personally I'm a propent of the view that a population will generally reach an equilibrium regarding evolution, especially if it's a social species. I think most "advantages" are the result of changes in the environment. A stable population really has no need to undergo significant change. But brain change is particularly radical. High energy costs, outrageous nutritional requirements, and extreme vulnerabilities (the main ones being that our development process is very long and involved, and that we have to give birth to babies when they're at a low stage of development because the head becomes so large so fast that otherwise it wouldn't fit through the pelvis). If a population is doing just fine, there is little reason for such extreme changes to be selected for (especially since the selection process itself is likely to be convoluted).

This is, I think, probably part of why a lot of adaptations do appear to be "side effects" of other attributes, or to extend from them - it allows radical change to go in "steps."

[Phil153]

Regarding men vs women: if there is a genetic reason they live longer, it's more likely related to the fact that they need excellent health in their youth to create healthy offspring and endure the burdens of labour. A mother's health is a huge factor in the health and development of her offspring. A man's health in youth is not anywhere near as large a factor in producing healthy and virile offspring. Note that this (very plausible) hypothesis supports my interpretation of the reason for longevity.

Do you see how many ways we can spin plausible hypotheses completely at odds with one another? Without being thoroughly informed, we really can't say jack. At least not with the certainty and isn't-it-obvious manner often presented by atheists.

I'll get to the rest later.

[madnak]

I don't think it's plausible, actually, but that's off the subject. Your statement was:

[ QUOTE ]
I think all the evolutionary arguments for old age (tribes that had grandparents were fitter, etc) are nonsense.

[/ QUOTE ]

Which is putting it more strongly than I think is remotely typical of the atheists here. I do happen to have some knowledge of the subject and to have read about it, so I feel very comfortable explaining prevalent views. Natural history isn't exactly the hardest of sciences, but ruling it out as nonsense seems unjustifiable to me. Many people have certainly put a huge amount of effort into it - making sure it's flush with medical knowledge, archaeological findings, climate conditions, etc.

I've only made one statement in this thread with certainty, and that was definitely not in an "isn't-it-obvious" manner - it's not obvious, but is true that idea that the natural human lifespan is very short is a myth. That one's pretty solid. I think your statement in general is way off-base. Your anger at the well-presented and reasonable posts in this thread seemed to come out of the blue.

[Taciturn]

[ QUOTE ]

Women can't procreate after a certain age. Most men can't either, not because of infertility but because of other reasons. So how did we evolve to the point where some of us naturally live so many years? What's the darwinian explanation for elderly life?



[/ QUOTE ]

If by Darwinian, you mean genetic, couldn't the gradual failing of an organisms' systems (aging) have been the simplest way of ridding the world of older generations so that their offspring would have the opportunity to reproduce? Sure, some animals (insects, fish, etc.) don't really live to old age - they have some sort of death trigger tied to the act of reproduction. In mammals, it can't work like that. We have to nurse and raise our young. Since we can't have a reproduction induced death trigger, we can't have a trigger at all. (What would it be? Some sort of genetic Logan's Run that occurs after we have reached an age that our offspring are generally self-sufficient? That just seems too complex to result from evolution. Those species that spontaneously die have a specific trigger, don't they? So, us mammals just fade away.)

If you were using Darwinian in a more general sense - I'm pretty sure advances in medicine, sanitation, technology, and so on can explain how humans can often lead long lives.

[chezlaw]

[ QUOTE ]
Regarding men vs women: if there is a genetic reason they live longer, it's more likely related to the fact that they need excellent health in their youth to create healthy offspring and endure the burdens of labour. A mother's health is a huge factor in the health and development of her offspring. A man's health in youth is not anywhere near as large a factor in producing healthy and virile offspring. Note that this (very plausible) hypothesis supports my interpretation of the reason for longevity.

Do you see how many ways we can spin plausible hypotheses completely at odds with one another? Without being thoroughly informed, we really can't say jack. At least not with the certainty and isn't-it-obvious manner often presented by atheists.

I'll get to the rest later.

[/ QUOTE ]
I think you're way over-reacting. This is a speculative thread about evolutionary reasons for eldery people. Of course it could just be an accident, or it could be some wierd slection of mates that come with mother-in-laws but generally resource maximisation and prey-predator models match fairly well with reality.

but they probably only match well if there's a prolonged survival arms-race and it may be that with some species primate and humans in particular, they haven't had enough of this to make the models work well.

but the thread is speculative, hypothesis need testing and its nothing like religon.

chez

[kevin017]

yea this thread kinda started going nuts with people trying to pin down little nuances.

people live to old age because it isn't strongly selected against, and could perhaps be selected for in small ways, such as you taking care of your offspring or providing other mild benefits. Or it could be genetically linked to some other more important trait. Or a combination of the above. we tend to take care of people past reproductive age for some reason we don't really know, probably a combination of their will to survive, finding cures for their diseases leading to an increase in our own lifespan/reproduction, and dumb luck on their part. the end.

[Jiggymike]

Sorry, I got bogged down in this thread so didn't read everything but still wanted to make a relevant post if possible.

OP's question is basically asking "Why do human beings live so far past their reproductive ages, in terms of evolutionary fitness?" Saying, "They are taken care of by younger people" and similar comments does not answer the question at all. It is probably easier not to just ask this about human beings but to ask it about ALL animals that live a long time past their reproductive ages - turtles, crocodiles, elephants, birds, etc. It would seem logical for organisms to degrade pretty quickly after they reproduce with a simple interpretation of natural selection if that was the only aspect being selected of .

However, organisms are complex beings with lots of different factors that affect how long they live. Currently I am in grad school for systematic biology (figuring out how organisms are related to each other...I actually find it quite hokie but that is another aspect altogether) and here's how we would approach the problem:

-Measure the lifespans of a bunch of creatures from disparate groups - mammals, birds, turtles, lizards whatever, and the groups within them.
-Compare closely related species which have a large disparity in lifespans. These are the groups we are looking for, because presumably they will provide the most information on the subject.
-Look for patterns within groups or across larger groups of organims.

I'm not sure if anything like this has been studied or if we have any good reasons right now as to why some animals live longer than others. For mammals, size appears to be a factor - larger mammals just seem to have longer lifespans than smaller ones. This could be a result of them having slower metabolisms and metabolism being the cause of aging, senesence, and eventally death (this is one of the theories supported right now). But like I said earlier, there are probably a number of factors at play, most of them poorly understood. It may just be that bodies are built to live and reproduce and lifespan is just an offshoot of this. Like madnak (I think) said, there is no reason to die right after reproduction but it is less costly to make a body that lives shorter (presumably). Basically, we do not know the factors that cause long life vs short life. Human beings DO benefit from health care and technology, however, extending lives to >100 years yet we seem to be pretty well built to last a long time with nothing but our immune system and organ systems.

[tame_deuces]

Well, skewered statistics or 'statistical illusion' is probably the main reason.

I mean, no doubt we can now prolong life with the use of medicine, diet etc. But I think the main reasons for the increase in life expectancy is that numbers from deaths at birth and child deaths have lessened drastically due to cultural advances in medicine and way of living.

[vhawk01]

[ QUOTE ]
Well, skewered statistics or 'statistical illusion' is probably the main reason.

I mean, no doubt we can now prolong life with the use of medicine, diet etc. But I think the main reasons for the increase in life expectancy is that numbers from deaths at birth and child deaths have lessened drastically due to cultural advances in medicine and way of living.

[/ QUOTE ]

As madnak pointed out earlier, this is more or less a myth. Cultures with little technology or medicine still see average lifespans that are much longer than average reproductive lifespans. Industrialization and other factors SHORTENED the human lifespan, which we've now had to compensate for. Certainly, the modern ~78 year lifespan is a result of technology, medicine, etc., but a more modest, 40-50 year lifespan isn't.

[chezlaw]

Moving on from the mother-in-law joke, it would make sense to select mates with surviving parents in the same way we select mates that are symmetric.

Both indicate that your mate has fit genes - your genes are fitter if they avoid you mating with someone who is likely to die before the children are reared or whose children are likely to die before they can reproduce.

Disclaimer: this is speculative.

chez

[tame_deuces]

[ QUOTE ]
[ QUOTE ]
Well, skewered statistics or 'statistical illusion' is probably the main reason.

I mean, no doubt we can now prolong life with the use of medicine, diet etc. But I think the main reasons for the increase in life expectancy is that numbers from deaths at birth and child deaths have lessened drastically due to cultural advances in medicine and way of living.

[/ QUOTE ]

As madnak pointed out earlier, this is more or less a myth. Cultures with little technology or medicine still see average lifespans that are much longer than average reproductive lifespans. Industrialization and other factors SHORTENED the human lifespan, which we've now had to compensate for. Certainly, the modern ~78 year lifespan is a result of technology, medicine, etc., but a more modest, 40-50 year lifespan isn't.

[/ QUOTE ]

Urr...yeah?

Industrialization caused increase in civilization and bringing people together in larger clusters increases the factors that cause child death exponentially, like the spread and evolution of disease. Untill medicine and cultural development in personal living can catch up.

C'mon, this is completely basic stuff, one only needs to look at cities growing too fast to see exactly the same pattern in today's world.

[vhawk01]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Well, skewered statistics or 'statistical illusion' is probably the main reason.

I mean, no doubt we can now prolong life with the use of medicine, diet etc. But I think the main reasons for the increase in life expectancy is that numbers from deaths at birth and child deaths have lessened drastically due to cultural advances in medicine and way of living.

[/ QUOTE ]

As madnak pointed out earlier, this is more or less a myth. Cultures with little technology or medicine still see average lifespans that are much longer than average reproductive lifespans. Industrialization and other factors SHORTENED the human lifespan, which we've now had to compensate for. Certainly, the modern ~78 year lifespan is a result of technology, medicine, etc., but a more modest, 40-50 year lifespan isn't.

[/ QUOTE ]

Urr...yeah?

Industrialization caused increase in civilization and bringing people together in larger clusters increases the factors that cause child death exponentially, like the spread and evolution of disease. Untill medicine and cultural development in personal living can catch up.

C'mon, this is completely basic stuff, one only needs to look at cities growing too fast to see exactly the same pattern in today's world.

[/ QUOTE ]

Right, so the point is, it ISN'T medicine and culture that allow human beings to live far past their normal reproductive age. Human populations with almost no medicine or technology ALSO do this. There is a reason for it, and it isn't 'statistical anomaly.

[vhawk01]

[ QUOTE ]


Er...no? Reread my point if you think I said that.

The point is that getting to 40 is the hard part. The 40-60 bit isn't that hard.

And don't claim I have said anything about a 'statistical anomaly', I haven't mention anomaly with a single word and never would, because it isn't an anomaly.

If I can't get you to understand that a bunch of numbers between 0 and 10 will lower drastically the average of a variable with the capacity to reach 75, then I give up.

if you believe that the entire population of the world has in a hundred years EVOLVED as a whole into doubling the length of time their body can live, then you are welcome to it.

But I hope most people will realize what a completely propostrous idea that is.


[/ QUOTE ]

Of course. It seemed to me you were dismissing the whole idea. Your exact term was 'skewered statistics or statistical illusion.' Sorry if I converted that to statistical anomaly...?

The question isn't about why we live to be 100, so your answer about medicine and technology is silly. The question is why do we live to 40. Thats what all of this thread has been about.

[PairTheBoard]

The most vital long lived males had more chances to reproduce right up to death. I understand for Jack LaLayne's 93rd Birthday feat he plans on impregnating 100 women while swimming underwater to hawaii towing a fully loaded oil tanker. This may have been true for women too at one time, with menopause evolving for some other reason. Or maybe the longgevity gene evolved by men gets passed on to female offspring too.

What puzzles me is why we haven't evolved to live longer. It seems like death is a pretty definite negative to the evolutionary goal of survival.

PairTheBoard

[MidGe]

[ QUOTE ]
First of all, if you don't believe in, or don't understand evolution as a reasonable scientific theory, REFRAIN from posting in this thread. Please.


[/ QUOTE ]


Ummm! You think evolution is a reasonable scientific theory, but a change in longevity of life over a thousands years, you attribute to evolution?

Are you suggesting, also, that every state, experienced now, is the somehow the best, of evolution?

Back to evolution 101, dude! /images/graemlins/smile.gif

[Mickey Brausch]

[ QUOTE ]
Thanks. Senior citizens can still serve a purpose.

[/ QUOTE ]Soylent Green ?

[Mickey Brausch]

[ QUOTE ]


Are you suggesting, also, that every state, experienced now, is the somehow the best, of evolution?



[/ QUOTE ]Let me add that, aside from local developments, evolution does not necessarily signify a general trend of progress or improvement.