I’m sitting here getting older. I hear my hair is falling out because there is an accumulation of DHT in my scalp. I hear the fat is accumulating around my waist because my metabolism has slowed down. I’ve read about the biological clocks called telemeres (sp) that tell our cells to stop dividing or whatever. My question is, why don’t we just reach puberty, live to help our offspring raise their offspring, and then drop dead looking like we did at 20? There doesn’t seem like any compelling biological reason that organs should “wear out.” Nature has a wide range of life spans. It doesn’t seem to be a matter of conservation of resources (a 70 year old man eats roughly the same amount as a 30 year old until he dies.) I know we have to drop dead at some point because the nature of life is to adapt and a longer lifespan would be an unnecessary drain on resources, but why make it painful?
Are there life forms that do just drop dead and don’t “get older” ie less efficient biologically?
One thing I was thinking was that the elderly need to get more feeble to increase the need to pass on leadership/life skills to the next generation. If the old didn’t become feeble, they wouldn’t be motivated to show Little Johnny how to hunt deer for them. Anyone know of have an idea?
i think that’s what people used to do (drop dead after prime mating/childrearing years) before the advent of medicine and such. there’s not really a need to “help your offspring raise their offspring” so i think you could get all your life’s work done by mid 20’s still being at the top of your game. i also think that old people are only a recent addition to the evolutionary scheme of things.
a lot of things drop dead after mating. salmon, mayflies etc
my 2 cents
No, the process of aging (balding, growing feeble, etc.) has no evolutionary advantage. Those ‘abilities’ manifest themselves long after the ability to reproduce, and evolution only has influence on abilities that occur before and during the reproductive age. So the human body really wasn’t ‘designed’ to live so long, long life being the result of cinilization, vaccinations, medicine, abundant food, clean water, Powerbars, etc- the things our distant ancestors struggled for. Since we really weren’t intended to live so long, we get arthritis, backaches, enlarged prostate, etc- the joys of getting old.
I hope this makes sense to you.
Part of it is a conservation of resources. Most of the disadvantages of old age arise from biological factors which are advantageous when we’re young. Obviously, it makes more sense for the youngest ones to have the biological advantages, because statistically some of those who make it to twenty won’t make it to forty.
First, I’m certainly no expert, and others who are more knowledgeable may be along shortly to correct me, but here’s my take on it.
Remember that the various things that make up the evolutionary pressure on a population don’t cause changes. Rather they select either in favor of or against small differences between members of a population, and between small changes that occur in members of a population from generation to generation.
In order to for something to have an evolutionary “purpose”, it must be something that affects overall survivability or ability to reproduce, or both. Evolutionary pressure doesn’t cause these changes, it only selects among them. It selects against some because they don’t contribute to the overall survivability of the group or don’t reproduce as well, or both. It selects for others because they contribute more to survivability of the group, or have better reproductive ability, or both.
So in order for evolution to keep us from growing more feeble as we age, there would have to be a combination of heritable changes from generation to generation, or a sudden appearance of a heritable mutation, that would both cause us to not grow as feeble as previously, and have an effect on the survivability of the group or the ability to reproduce, or both.
Evolutionary pressure doesn’t cause a change like this to occur, no matter how good it might be for us, it just selects for or against such a change if it does occur.
Since until fairly recent times our population was skewed toward younger people by virtue of disease and accidental death, there hasn’t been a lot of pressure to keep us healthier for longer times. So even if there have been people born who stayed healthier longer for some heritable reason, their genes haven’t spread out and become common in the gene pool.
And having said that, does anyone know how we compare in this regard to our remote ancestors? Go back a quarter or half a million years and we may well be the picture of old age health compared to them.
Ugly
No, the process of aging (balding, growing feeble, etc.) has no evolutionary advantage. Those ‘abilities’ manifest themselves long after the ability to reproduce, and evolution only has influence on abilities that occur before and during the reproductive age. So the human body really wasn’t ‘designed’ to live so long, long life being the result of cinilization, vaccinations, medicine, abundant food, clean water, Powerbars, etc- the things our distant ancestors struggled for. Since we really weren’t intended to live so long, we get arthritis, backaches, enlarged prostate, etc- the joys of getting old.
I hope this makes sense to you.
Let’s face it, from an evolutionary standpoint, once we’ve had kids and raised them to the point where they can have kids of their own, we’re sacks of meat, wasting valuable resources that could be going to them instead.
So in that sense, teenagers are surly for a reason. 
But I’m still sticking around anyway, just to cheese 'em off. 
Why we age and why we die are in principle two different, though related, questions. One common explanation for death amongst animals like mammals is that there’s no selection preference for extending the “natural” lifespan of creatures who are likely to be killed anyway. There’s suggestive evidence that lifespans are correlated with the likelihood of death through predation or accident. No point in natural selection “investing” in longer lifespans when other factors are likely to get you anyway. With humans, whether those factors apply in recent environments is another matter, but we could still be playing catch-up. Given that we will die, there is then pressure for us to maximise our reproductive effectiveness prior to our likely date of death. There’s thus the argument, due to the late W.D. Hamilton, that all our growing/aging processes are optimised for this finite lifespan. Hair falls out, skin crinkles, menopause kicks in, not for any positive reason, but for the negative reason that there’s a point beyond which it’s statistically useless to maintain the youthfull capabilities instead of enhancing them in our prime. In short, few people live to 100, so ensuring that hair lasts to that age is actually counter-productive. The pessimistict conclusion is that “curing” aging in the short-term is not correcting a single factor, it’s dealing with a multitude of independent processes, none of which are currently optimised for anything other than a relatively short span of years.
Yes, but the original purpose is thwarted because we lack “Tree of Life” on this planet. If we had “Tree Of Life” our evolutionary growth cycle would be complete with our metamorphosis into our “Protector” stage of growth.
See “Protector”, “Ringworld”, “Ringworld: Engineers”, and “Ringworld: Throne”, by Larry Niven for details.
The elderly are definately not “sacks of meat” and, afaik, nature doesn’t simply select for traits up to the time of procreation and child rearing. There was a show on the Discovery Channel once (no cite) that theorized that the reason we live so long after our procreative years is that the elderly aid in child rearing. So “long life” is selected for by virtue of the increased probability of getting a child to the next procreation cycle. If this aspect of post-procreative attributes can be selected for, so can “feebility” ( 
)
Feebleness in aging humans does not have a “purpose” built into it by evolution.
It is Wrath of God, pure and simple, for our prideful and dissipated youthful years.
It is a mistake to assume that all traits of an organism serve some adaptive purpose. From a strictly Darwinistic point of view, one would have to view aging and death as most certainly non-adaptive, since immortality would far better serve the purpose of spreading one’s genes to future generations - the longer one lasts, and reproduces, the more one’s genes are perpetuated.
Ultimately, we age (and subsequently die) because we are not optimized. Like any imperfectly built machine, we begin to break down. There is no “purpose” for this happening, it is simply a consequence of our construction.
Gradually, we are overcoming this imperfection through nutrition, health care, implants, etc., such that lives can be prolonged to a greater degree as time goes on. Again, this isn’t because of any particular adaptation; we are, like any good mechanic, learning how to “fix” our own bodies, thus resulting in greater longevity.
Darwin, the point that you make about passing on one’s genes for as long as we can is OK except that after a while those genes aren’t what they used to be. Faulty replication in sperm and environmental damage in eggs. (If I recall my biology, sperms are constantly formed and eggs are always there from puberty if not earlier) make the genetic transmission faulty. Enfeeblement and death (both of which are major turnoffs when it comes to sex) keeps the damaged/worn out genes of the elderly out of the pool. If we (meaning all life) had some sort of individual digital replication of genes, maybe death would not have “evolved” back in the Archaeozoic. But, individually, are genes eventually become more like a Xerox of a Xerox of a Xerox …
Actually, I think death is second only to birth in a creature’s ability to adapt. If we didn’t die we would crowd out future generations by using resources. Also, the species would not adapt to changing conditions though natural selection.
Death has nothing to do with adapting. Individuals don’t adapt - species do. Besides which, the whole idea behind natural selection is that those individuals who have a better chance of surviving get the resources, whereas those who are not, don’t. It has nothing to do with allowing future generations to utilize those resources. There are any number of instances in the animal world wherein one’s offspring become comptetition, one consequence of which is that the offspring can wind up as food for the parent(s).
Think of it this way: if nothing ever died, there would be no need to reproduce, no need even to adapt and evolve. Thus, one need not concern oneself with future generations.
Because organisms aren’t perfect, eternal machines, however, a struggle for life ensues. Resources go to those best able to utilize them (in the natural world; humans have superceded or circumvented this to a great extent), and those individuals generally pass on their genes to future generations.
Death serves no purpose in Nature’s grand scheme (to anthropomorphize a bit) beyond requiring reproduction (which, coupled with the imperfection of DNA replication, permits evolution to occur in the first place), and adding a sense of urgency to its practice.
In all of recorded history, and perhaps much earlier, there has been some reproductive advantage in long life, at least for men. This is because human societies are often dominated by aging males whose political skills make up for their waning physical strength. Such men can father children well into their old age. I can’t see any similar advantage in longevity genes for women because they lose their fertility. However, any increase in the frequency of longevity genes among men will be shared by women, except for those few genes that might be sex-linked.
Whether the phenomenon of fertile patriarchs is old enough to have significantly extended our lifespans beyond our reproductive years, I can’t say, but I think it’s a theoretical possibility.
There is an advantage to some aspects of aging. The OP said:
I’m not an expert, but I’ve read a bit about this.
Telemeres aren’t exactly dependant on time elapsed, rather they act to weaken the cell based on the number of times the cell has divided (with variation based on the number of times the cell is expected to divide- in healthy cells, this is related to age.) In a young human, this will have little affect normally, but there’s one exception- cancer. Cancer cells reproduce much more rapidly than other cells, and the telemeres act to weaken them. This is one reason why chemotherapy works- cancerous cells are weaker than normal cells, and they’re weaker because they have reproduced themselves more than non-cancerous cells.
This is particularly important when considering an approach to treating aging by altering telemeres- doing so may remove a natural cancer defense.
There is an advantage to some aspects of aging. The OP said:
I’m not an expert, but I’ve read a bit about this.
Telemeres aren’t exactly dependant on time elapsed, rather they act to weaken the cell based on the number of times the cell has divided (with variation based on the number of times the cell is expected to divide- in healthy cells, this is related to age.) In a young human, this will have little affect normally, but there’s one exception- cancer. Cancer cells reproduce much more rapidly than other cells, and the telemeres act to weaken them. This is one reason why chemotherapy works- cancerous cells are weaker than normal cells, and they’re weaker because they have reproduced themselves more than non-cancerous cells.
This is particularly important when considering an approach to treating aging by altering telemeres- doing so may remove a natural cancer defense.