7 ms·

Complete bollocks. Molecules don't age and everything in your body is molecules. If a molecule breaks down, in some cases the body has mechanisms to replace it

Complete bollocks. Molecules don't age and everything in your body is molecules. If a molecule breaks down, in some cases the body has mechanisms to replace it with a shiny new one. Those mechanisms are themselves made of molecules. And if those mechanisms to stop working, in some cases those mechanisms can also be replaced. Nothing in fundamental physics makes aging inevitable. From what I can tell, the reason why aging is so prevalent is that most species haven't had time to evolve the mechanisms that solve the problems that appear later in life. If there's some truth to this, you'd expect that the species that are better at this also tend to be the simpler ones, since for those simplicity also means smaller diversity of things going wrong.

rubenbe 9y ago
Nature has not been able to solve the problem of ageing because natural selection does not work at later age. The organism has already successfully procreated, so there is no survival of the fittest.
- fwdpropaganda 9y ago
  Not true. Procreation is not binary. More is better (evolutionarily speaking), so there's no reason for "once you have one offspring you're evolutionarily dead." No, you could have more.
  - XorNot 9y ago
    On some level humans are the pinacle of the solution to survivability. We live in every biome on the planet, and are actively researching giving ourselves immortality. We're so successful that the best strategy for a lot of other animals has been to be food or company. Cows are doing pretty well because of us.
- kabouseng 9y ago
  Not really, if you stay young forever you can procreate forever and "out" procreate the rest of your species that still ages.
  - jamesrcole 9y ago
    But they're not really your competition. Their offspring, and their offspring, and so on, are. And "designs" that don't have to put resources into longer life can use them for better propagating genes.
- deleted 9y ago
  [deleted]
- andrewla 9y ago
  That's if you take a very narrow view of individual selection. A group of organisms collectively may have favorable selection characteristics compared to another group that dies younger, even if the death is post-reproductive age. Bees, for example, have evolved to have very strong but non-reproducing organisms in a community. There's still selection pressure on a hive to produce stronger and longer lived workers. As I understand it, the general mechanism involved here is usually called kin selection, and has been discussed as far back as Darwin, both as a potential problem with the theory and as a fatal defect in the Lamarckian view.
- gerbilly 9y ago
  >Nature has not been able to solve the problem of ageing Nature does not have an ageing problem. Aging and dying is a necessary condition for life to even exist. It's only humans who have a problem with it.
  - AnIdiotOnTheNet 9y ago
    Only humans who have a very narrow conception of self. People sacrifice themselves for family, communities, nations, and ideologies all the time.
- a3n 9y ago
  Might older organisms' collective life experience contribute to the success of younger organisms? In other words, the organism's procreation could be more successful if the olds contribute to the youngs survival to reproductive age. In other other words, you haven't really reproduced if your offspring don't reproduce.
fooker 9y ago
Most (/all?) species reproduce in their prime. The problems that occur later in life do not have any affect on that. On the other hand, for communities and 'tribes', not keeping old members around make them more responsive to change.
- fwdpropaganda 9y ago
  I understand you're not disagreeing with the core of what I said, but I have to point out your circular logic. Why do species have a prime? Why don't they reach a certain "amount of reproductibility" and stay at that constant amount forever? The fact that a prime exists is just one instance of one of those things that evolution hasn't figured out yet. Or maybe there's a different reason why it hasn't happened, but that reason is certainly not fundamental physics.
  - jamesrcole 9y ago
    Not the person you're replying to, but the theory I've heard is the following. The background for this theory is that evolution is gene-centric, not individual-centric. What is fitter is what will better propagate the genes, which is not necessarily what's best for the individual. So it can build "designs" that have a better chance of propagating genes earlier on, where features that help that (I'm making this example up, but say something like faster growth) may later have a deleterious affect on the individual. And since evolution is gene focused, there's not as much evolutionary pressure for a longer and healthier life for the individual.
  - Tepix 9y ago
    If you leave out the repair mechanisms you save a lot of resources.
    - fooker 9y ago
      Interesting point. This has a nice analogy in coding theory. In general you can do things significantly faster with a lower number of bits if you leave out the redundancy required for error detection or correction.
isolli 9y ago
I once read (but can't find a citation) that trees that live to be thousands of years old grow in stable environments that have not changed in millions of years.
- pc86 9y ago
  There is not a single area of the planet that hasn't changed for millions of years.
sametmax 9y ago
> If there's some truth to this, you'd expect that the species that are better at this also tend to be the simpler ones, since for those simplicity also means smaller diversity of things going wrong. I doubt it. IMO, aging is just a way to ensure that dying occurs. And dying is necessary for evolution, as it's easier to replace the old with a new generation that understand better the reality than changing the current generation. Old habits literally die hard.
- prawks 9y ago
  Interesting. So by that line of thought, aging would be an evolved trait giving certain species an evolutionary advantage over others without aging.
  - superasn 9y ago
    So that would be like killing a program and respawning a new process instead for some benefit like reclaiming memory or speed (like I do with browser tabs). I know evolution doesn't work that way, but definitely sounds like an interesting thought.
    - devnonymous 9y ago
      > So that would be like killing a program and respawning a new process instead for some > benefit like reclaiming memory or speed ... > > I know evolution doesn't work that way, Sure its better now but that's how the early versions of Evolution worked (sorry couldn't resist !).
      - navaati 9y ago
        For downvoters, I guess parent is making a reference to the Evolution mail/calendar client from Gnome. Which is (was ?) indeed a memory hog.
  - sarumpaet 9y ago
    This is, to a degree, what happens. However, a species that ages has an advantage in that new individuals, with perhaps better characteristics in the face of new circumstances, have access to more resources. I do wonder whether there is a point where the lost experience of other individuals weighs heavier than physically better adapted individuals. In a way, culture serves as a way to preserve information that would be lost by aging.
mavdi 9y ago
It's obvious that you probably only read the first paragraph of the article.
xelxebar 9y ago
It seems like you got snared by the title. My gut reaction was the same, but I was pleasantly surprised by the article. Its main point is that ageing follows a roughly Gompertz-Makeham distribution, the statistics of which also nicely describe "wear-and-tear" processes like protein breaking. The final paragraph even explicitly addresses the concerns you raise about possible routes to intervention in ageing processes.
andrewla 9y ago
Agreed -- I even think that we have concrete proof of exactly this. Namely that immortality already exists in the form of reproduction, if we discard the notion of an individual identity. Just as cells in our body have a much shorter lifespan than the body itself, so does the family or community have a longer lifespan than any individual member.
Retric 9y ago
Actually, Atoms are unstable on very large time scales. So, a block of gold will eventually stop being a block of gold. You still see lifetimes next to 'stable' elements because nothing is actually stable on long enough time scales. Granted, 10^~45 years may seem like a long time, but I am sure it would still feel short if that was the norm. ;-)
- garmaine 9y ago
  I’m ok with my lifetime being limited by the decay rate of the proton.
Moodles 9y ago
> most species haven't had time to evolve the mechanisms that solve the problems that appear later in life Or evolution isn't interested in this outcome. It is probably benefitical for a species if members die once they get old, to make way for the new.
- YCode 9y ago
  Yeah, more resources for the newer generation and more adaptability from generations occurring more frequently. The extreme of this might be HIV or the common cold.
  - hans05 9y ago
    Another possibility is that aging is actually a side effect of some other important process. This would make it difficult to evolve ways to slow down aging without affecting the original process. My guess is that aging is somehow related to growth rates since organisms with longer life spans like humans or turtles often take a long time to reach maturity. Most forms of life need to reach full size as quickly as possible followed by a rapid stop in growth once full size is reached. Perhaps the rapid stop in growth causes problems with the body's repair mechanisms which ultimately lead to aging. This would be kind of like a business or city which experiences a sudden stop in growth that eventually leads to breakdowns as there is no longer enough money to maintain the infrastructure built up during the growth phase. The physics based theory in the article can't explain why similar forms of life age at very different rates (i.e. dogs aging 7x faster than humans) so something else must be going on.
- SonicSoul 9y ago
  that sounds right. evolution needs to iterate and iteration stops when generations don't die out? Unless perhaps we figure out how to evolve single generation in progress.
- knome 9y ago
  Evolution isn't "interested" in any outcome. There's no need to anthropomorphize it. There doesn't need to exist some conspiracy in a species to explain death. The new compete with the old for resources, mates and avoiding predators ( don't need to be faster than a bear, just faster than your friends ). The old have a lifetime of cellular damage, injuries, diseases etc having done damage to their bodies. These things make them more susceptible to predators and dying, being unable to mate do to body problems, being unable to compete for mates and being unable to compete for resources and dying. Evolution can only select for that which leads to reproduction and survival of progeny. Whatever happens to an animals body after it passes on genetic material is of no matter to the new animal, excepting where interactions with the existing creature can be of benefit and detriment to the young. A mother crocodile protecting her young will have more surviving young than one that eats them, and the former will tend to out-compete the latter and continue existing. Assuming a long-lived effectively-immortal species that only reproduces when resources are available for doing so exists, what would happen if a single gene for fast reproduction arose? Resources would run out, and animals would have to start competing with one another over them. Assuming the old and the young are both 50/50 for living or dying in any given fight, the creatures that reproduce slower would be at a disadvantage because there would always be more and more of the fast reproducers. The only stay for the fast reproducers would be whether they can keep their young alive. So perhaps if they have young one or two at a time instead of twelve at a time, their one or two might be more likely to survive to adulthood whereas the twelve would tend to die well before then. In the end a balance would emerge where members of the species would tend to reproduce as much as possible where they expect to be able to properly nuture the offspring. Those reproducing slower would fail to compete for resources. Those reproducing faster would fail to keep their offspring alive. But certainly, those that are steadfastly not reproducing for "the good of the species"? These would be out-competed in short order by the rest.
atmanthedog 9y ago
Molecules don't age, but any collection of molecules with distinguishable states will eventually relax spontaneously to a higher entropy configuration. Keeping a system a certain way requires an input of energy, and eating can satisfy this up to a point, but I think the complexity of the central nervous system in certain animals eventually makes this impossible. It isn't hard to keep any particular process 'alive'. Stars burn for a long time. The hard part comes with maintaining a process that also requires memory of the past. What would seem to be the difference between a star and biological life is that life maintains a record of some information of its past states in its DNA. However, even on top of this, many animals, especially birds and mammals, have to teach their young and train an incredibly complexly connected brain. So I think what you end up with is an optimization that trades off between these two complexity drives: a mind and a body. An organism that has invested a lot of time into training its nervous system does not want to completely regenerate it and lose all of that information. However, from a bodily perspective, being able to regenerate would be quite useful. However, making processes more reversible comes at a price (notably, thermodynamically, it would take infinite time. computationally, reversibility requires n^2 steps for some irreversible computation done in n steps), one that is no longer worth the tradeoff if the mind cannot be usefully regenerated. I guess my point overall is that the brain, since it wants to store information, is inherently destined for breakdown. Regenerating it might be possible, but the interconnections might be so complex that it would be energetically infeasible to maintain this complexity. In humans, the brain already utilizes 20% of our energy budget. As the organism as a whole is being optimized through evolution to do evolutionary favorable things with its energy budget, this means that energy spent maintaining itself physically indefinitely is not worth it, as compared to something like a lobster, which ostensibly doesn't have the sorts of pyramidal neurons needed for a truly, truly complex nervous system and thus might as well live forever. I assume that people will disagree with the idea that the brain is destined to break down, but if you were 10000 years old today, would you still consider yourself the same person that used to hang out with the pharaohs, having learned and forgotten hundreds of languages, names, families? It just gets absurd at some point, and the energy cost of it all is not worth it compared to reboot(strapp)ing everything from the ground up by having a child. It is interesting the the mole rats are so long lived, and that they are also eusocial. Since institutional memory may be very important to the colony's survival, having long-lived individuals may be very helpful for an animal incapable of writing things down for posterity. I would still say that this is all very firmly grounded in thermodynamics.
deleted 9y ago
[deleted]
saalweachter 9y ago
So I think it's helpful to think about aging and death on two levels: cells and organisms. Organisms age and die when their cells age and die. An organism can not age and die by either replacing its cells as fast as they die, perfectly, or by having cells that don't die. Why do cells die? The article presents two views: either they are programmed to, for biological reasons, or they just break down over time, because engineering is hard and physics is a real mother. It'd be real convenient for us if it was the former, because humans aren't built to have all our cells constantly replaced throughout our life, but this article makes the argument that programmed cell death is unlikely and physical wear and tear more plausible.
klmr 9y ago
> Molecules don't age But they do. The article argues that molecule ensembles are damaged by thermal motion but there are other ways in which molecules are damaged over time due to chemical and physical stress. Large molecules in the cells are bombarded by caustic chemicals (oxidative stress) and ionising radiation, both of which break chemical bonds. Even without these, many molecules in the cell are only temporally stable and decay over time (e.g. single-stranded RNAs are unstable even ignoring active degradation). It is altogether accurate (and common!) to describe these processes as ageing on the cellular level. As you’ve correctly noted, cells constantly repair and replace damaged molecules.

rubenbe 9y ago

Nature has not been able to solve the problem of ageing because natural selection does not work at later age. The organism has already successfully procreated, so there is no survival of the fittest.

fwdpropaganda 9y ago
Not true. Procreation is not binary. More is better (evolutionarily speaking), so there's no reason for "once you have one offspring you're evolutionarily dead." No, you could have more.
- XorNot 9y ago
  On some level humans are the pinacle of the solution to survivability. We live in every biome on the planet, and are actively researching giving ourselves immortality. We're so successful that the best strategy for a lot of other animals has been to be food or company. Cows are doing pretty well because of us.
kabouseng 9y ago
Not really, if you stay young forever you can procreate forever and "out" procreate the rest of your species that still ages.
- jamesrcole 9y ago
  But they're not really your competition. Their offspring, and their offspring, and so on, are. And "designs" that don't have to put resources into longer life can use them for better propagating genes.
deleted 9y ago
[deleted]
andrewla 9y ago
That's if you take a very narrow view of individual selection. A group of organisms collectively may have favorable selection characteristics compared to another group that dies younger, even if the death is post-reproductive age. Bees, for example, have evolved to have very strong but non-reproducing organisms in a community. There's still selection pressure on a hive to produce stronger and longer lived workers. As I understand it, the general mechanism involved here is usually called kin selection, and has been discussed as far back as Darwin, both as a potential problem with the theory and as a fatal defect in the Lamarckian view.
gerbilly 9y ago
>Nature has not been able to solve the problem of ageing Nature does not have an ageing problem. Aging and dying is a necessary condition for life to even exist. It's only humans who have a problem with it.
- AnIdiotOnTheNet 9y ago
  Only humans who have a very narrow conception of self. People sacrifice themselves for family, communities, nations, and ideologies all the time.
a3n 9y ago
Might older organisms' collective life experience contribute to the success of younger organisms? In other words, the organism's procreation could be more successful if the olds contribute to the youngs survival to reproductive age. In other other words, you haven't really reproduced if your offspring don't reproduce.

fooker 9y ago

Most (/all?) species reproduce in their prime. The problems that occur later in life do not have any affect on that. On the other hand, for communities and 'tribes', not keeping old members around make them more responsive to change.

fwdpropaganda 9y ago
I understand you're not disagreeing with the core of what I said, but I have to point out your circular logic. Why do species have a prime? Why don't they reach a certain "amount of reproductibility" and stay at that constant amount forever? The fact that a prime exists is just one instance of one of those things that evolution hasn't figured out yet. Or maybe there's a different reason why it hasn't happened, but that reason is certainly not fundamental physics.
- jamesrcole 9y ago
  Not the person you're replying to, but the theory I've heard is the following. The background for this theory is that evolution is gene-centric, not individual-centric. What is fitter is what will better propagate the genes, which is not necessarily what's best for the individual. So it can build "designs" that have a better chance of propagating genes earlier on, where features that help that (I'm making this example up, but say something like faster growth) may later have a deleterious affect on the individual. And since evolution is gene focused, there's not as much evolutionary pressure for a longer and healthier life for the individual.
- Tepix 9y ago
  If you leave out the repair mechanisms you save a lot of resources.
  - fooker 9y ago
    Interesting point. This has a nice analogy in coding theory. In general you can do things significantly faster with a lower number of bits if you leave out the redundancy required for error detection or correction.

isolli 9y ago

I once read (but can't find a citation) that trees that live to be thousands of years old grow in stable environments that have not changed in millions of years.

pc86 9y ago
There is not a single area of the planet that hasn't changed for millions of years.

sametmax 9y ago

> If there's some truth to this, you'd expect that the species that are better at this also tend to be the simpler ones, since for those simplicity also means smaller diversity of things going wrong. I doubt it. IMO, aging is just a way to ensure that dying occurs. And dying is necessary for evolution, as it's easier to replace the old with a new generation that understand better the reality than changing the current generation. Old habits literally die hard.

prawks 9y ago
Interesting. So by that line of thought, aging would be an evolved trait giving certain species an evolutionary advantage over others without aging.
- superasn 9y ago
  So that would be like killing a program and respawning a new process instead for some benefit like reclaiming memory or speed (like I do with browser tabs). I know evolution doesn't work that way, but definitely sounds like an interesting thought.
  - devnonymous 9y ago
    > So that would be like killing a program and respawning a new process instead for some > benefit like reclaiming memory or speed ... > > I know evolution doesn't work that way, Sure its better now but that's how the early versions of Evolution worked (sorry couldn't resist !).
    - navaati 9y ago
      For downvoters, I guess parent is making a reference to the Evolution mail/calendar client from Gnome. Which is (was ?) indeed a memory hog.
- sarumpaet 9y ago
  This is, to a degree, what happens. However, a species that ages has an advantage in that new individuals, with perhaps better characteristics in the face of new circumstances, have access to more resources. I do wonder whether there is a point where the lost experience of other individuals weighs heavier than physically better adapted individuals. In a way, culture serves as a way to preserve information that would be lost by aging.

mavdi 9y ago

It's obvious that you probably only read the first paragraph of the article.

xelxebar 9y ago

It seems like you got snared by the title. My gut reaction was the same, but I was pleasantly surprised by the article. Its main point is that ageing follows a roughly Gompertz-Makeham distribution, the statistics of which also nicely describe "wear-and-tear" processes like protein breaking. The final paragraph even explicitly addresses the concerns you raise about possible routes to intervention in ageing processes.

andrewla 9y ago

Agreed -- I even think that we have concrete proof of exactly this. Namely that immortality already exists in the form of reproduction, if we discard the notion of an individual identity. Just as cells in our body have a much shorter lifespan than the body itself, so does the family or community have a longer lifespan than any individual member.

Retric 9y ago

Actually, Atoms are unstable on very large time scales. So, a block of gold will eventually stop being a block of gold. You still see lifetimes next to 'stable' elements because nothing is actually stable on long enough time scales. Granted, 10^~45 years may seem like a long time, but I am sure it would still feel short if that was the norm. ;-)

garmaine 9y ago
I’m ok with my lifetime being limited by the decay rate of the proton.

Moodles 9y ago

> most species haven't had time to evolve the mechanisms that solve the problems that appear later in life Or evolution isn't interested in this outcome. It is probably benefitical for a species if members die once they get old, to make way for the new.

YCode 9y ago
Yeah, more resources for the newer generation and more adaptability from generations occurring more frequently. The extreme of this might be HIV or the common cold.
- hans05 9y ago
  Another possibility is that aging is actually a side effect of some other important process. This would make it difficult to evolve ways to slow down aging without affecting the original process. My guess is that aging is somehow related to growth rates since organisms with longer life spans like humans or turtles often take a long time to reach maturity. Most forms of life need to reach full size as quickly as possible followed by a rapid stop in growth once full size is reached. Perhaps the rapid stop in growth causes problems with the body's repair mechanisms which ultimately lead to aging. This would be kind of like a business or city which experiences a sudden stop in growth that eventually leads to breakdowns as there is no longer enough money to maintain the infrastructure built up during the growth phase. The physics based theory in the article can't explain why similar forms of life age at very different rates (i.e. dogs aging 7x faster than humans) so something else must be going on.
SonicSoul 9y ago
that sounds right. evolution needs to iterate and iteration stops when generations don't die out? Unless perhaps we figure out how to evolve single generation in progress.
knome 9y ago
Evolution isn't "interested" in any outcome. There's no need to anthropomorphize it. There doesn't need to exist some conspiracy in a species to explain death. The new compete with the old for resources, mates and avoiding predators ( don't need to be faster than a bear, just faster than your friends ). The old have a lifetime of cellular damage, injuries, diseases etc having done damage to their bodies. These things make them more susceptible to predators and dying, being unable to mate do to body problems, being unable to compete for mates and being unable to compete for resources and dying. Evolution can only select for that which leads to reproduction and survival of progeny. Whatever happens to an animals body after it passes on genetic material is of no matter to the new animal, excepting where interactions with the existing creature can be of benefit and detriment to the young. A mother crocodile protecting her young will have more surviving young than one that eats them, and the former will tend to out-compete the latter and continue existing. Assuming a long-lived effectively-immortal species that only reproduces when resources are available for doing so exists, what would happen if a single gene for fast reproduction arose? Resources would run out, and animals would have to start competing with one another over them. Assuming the old and the young are both 50/50 for living or dying in any given fight, the creatures that reproduce slower would be at a disadvantage because there would always be more and more of the fast reproducers. The only stay for the fast reproducers would be whether they can keep their young alive. So perhaps if they have young one or two at a time instead of twelve at a time, their one or two might be more likely to survive to adulthood whereas the twelve would tend to die well before then. In the end a balance would emerge where members of the species would tend to reproduce as much as possible where they expect to be able to properly nuture the offspring. Those reproducing slower would fail to compete for resources. Those reproducing faster would fail to keep their offspring alive. But certainly, those that are steadfastly not reproducing for "the good of the species"? These would be out-competed in short order by the rest.

atmanthedog 9y ago

Molecules don't age, but any collection of molecules with distinguishable states will eventually relax spontaneously to a higher entropy configuration. Keeping a system a certain way requires an input of energy, and eating can satisfy this up to a point, but I think the complexity of the central nervous system in certain animals eventually makes this impossible. It isn't hard to keep any particular process 'alive'. Stars burn for a long time. The hard part comes with maintaining a process that also requires memory of the past. What would seem to be the difference between a star and biological life is that life maintains a record of some information of its past states in its DNA. However, even on top of this, many animals, especially birds and mammals, have to teach their young and train an incredibly complexly connected brain. So I think what you end up with is an optimization that trades off between these two complexity drives: a mind and a body. An organism that has invested a lot of time into training its nervous system does not want to completely regenerate it and lose all of that information. However, from a bodily perspective, being able to regenerate would be quite useful. However, making processes more reversible comes at a price (notably, thermodynamically, it would take infinite time. computationally, reversibility requires n^2 steps for some irreversible computation done in n steps), one that is no longer worth the tradeoff if the mind cannot be usefully regenerated. I guess my point overall is that the brain, since it wants to store information, is inherently destined for breakdown. Regenerating it might be possible, but the interconnections might be so complex that it would be energetically infeasible to maintain this complexity. In humans, the brain already utilizes 20% of our energy budget. As the organism as a whole is being optimized through evolution to do evolutionary favorable things with its energy budget, this means that energy spent maintaining itself physically indefinitely is not worth it, as compared to something like a lobster, which ostensibly doesn't have the sorts of pyramidal neurons needed for a truly, truly complex nervous system and thus might as well live forever. I assume that people will disagree with the idea that the brain is destined to break down, but if you were 10000 years old today, would you still consider yourself the same person that used to hang out with the pharaohs, having learned and forgotten hundreds of languages, names, families? It just gets absurd at some point, and the energy cost of it all is not worth it compared to reboot(strapp)ing everything from the ground up by having a child. It is interesting the the mole rats are so long lived, and that they are also eusocial. Since institutional memory may be very important to the colony's survival, having long-lived individuals may be very helpful for an animal incapable of writing things down for posterity. I would still say that this is all very firmly grounded in thermodynamics.

deleted 9y ago

[deleted]

saalweachter 9y ago

So I think it's helpful to think about aging and death on two levels: cells and organisms. Organisms age and die when their cells age and die. An organism can not age and die by either replacing its cells as fast as they die, perfectly, or by having cells that don't die. Why do cells die? The article presents two views: either they are programmed to, for biological reasons, or they just break down over time, because engineering is hard and physics is a real mother. It'd be real convenient for us if it was the former, because humans aren't built to have all our cells constantly replaced throughout our life, but this article makes the argument that programmed cell death is unlikely and physical wear and tear more plausible.

klmr 9y ago

> Molecules don't age But they do. The article argues that molecule ensembles are damaged by thermal motion but there are other ways in which molecules are damaged over time due to chemical and physical stress. Large molecules in the cells are bombarded by caustic chemicals (oxidative stress) and ionising radiation, both of which break chemical bonds. Even without these, many molecules in the cell are only temporally stable and decay over time (e.g. single-stranded RNAs are unstable even ignoring active degradation). It is altogether accurate (and common!) to describe these processes as ageing on the cellular level. As you’ve correctly noted, cells constantly repair and replace damaged molecules.