Why we age

Discussion in 'Biology & Genetics' started by francois, Feb 1, 2010.

  1. francois Schwat? Registered Senior Member

    There is a theory of aging that I particularly like. I read about it in one of Richard Dawkins's books. He referenced it as something akin to the Sub-lethal Gene Theory. I suppose it is probably the mainstream accepted explanation for why we age because it follows so naturally from the established principals of evolution. When one fully comprehends the theory, there is a sense of inevitability, as if it can't not be the explanation for why we age.

    In a sentence the theory can be summed up as: Aging is caused by the cumulative effect of sub-lethal genes.

    There is an old adage that goes something like "You can't do one thing." A way to put it more explicitly is that when you cause something to happen the event ripples and reverberates through all four dimensions through all spacetime, even though you were probably only trying to affect something near you. This is also true of genes.

    Because it is so often heard, "a gene for this..." "... a gene for that," in the media, it is easy to think that individual genes have a purpose, to, perhaps cause blue eyes or red hair. But genes don't work that way. Genes aren't like components in a radio, in which it can properly be said that transistor x is for purpose y, because unlike radios, animals and organisms aren't designed.

    In evolution, there is no purpose. In evolution a gene naturally and automatically accumulates in an organism because it is useful on average. If a gene is harmful to an organism in one respect, but extremely helpful to the organism in another respect, then natural selection will favor that gene and it will be caught and kept by the sieve for future use.

    Nevermind having a single purpose, a gene has no purpose. When a scientist says "a gene for x" he means in the presence of that gene, trait x is significantly more common, nothing more. It doesn't matter how indirectly the gene causes the physical effect. And it is common that genes produce their claimed purpose or physical effect very indirectly. Gene x switches on gene y, which references genes, xx, xy and yy, which code for and produce the proteins needed to start process xxxy, which switches off gene z, which statistically, almost always causes a person to have blue eyes. It turns out that gene x does many other things, such as cause the right big toe to be slightly shorter than the next toe in line, an allergic reaction to pollin, prolonged stage of shyness during adolescence and a like for spicy foods. Like an event in spacetime, the effects of a gene can branch out and touch in long, winded and unpredictable ways.

    All of our genes are lucky mutations, instructions that intruded into our bodies by chance but were deemed worthy of being kept by natural selection. That, or natural selection was momentarily away and they sneakily slipped through the unguarded walls. Mutations are random and are, therefore, mostly bad and harmful. There are many, many, more ways to be wrong than right. There are many, many, more ways to not hit the bull's eye than there are ways to hit the bull's eye.

    Genes exist and produce their effects in spacetime. Generally, it's most important that an organism be its fittest during its youth, in order to reach adulthood, and during its adulthood, so it can reproduce and see to it that its progeny have a fair shot at life. Genes are going to be selected to make it strong and fit specially during that time. But remember that genes can't do one thing. Each gene that does something good during that time of youth still exists after its period of usefulness and since it can't do one thing, it is does other things as well. Remember that most mutations are harmful, and pretty much, the rest of the story is told. The genes' usefulness are used up during youth; it's not important that they cause the organism to be strong during old age. As the organism gets older, increasing numbers of normal and helpful genes accumulate to defect against the organism by veering off in different directions and branching off in unpredictable ways. They fall out of phase with the organism. The result is a gradual accumulation of ill effects: weaker bones, poorer eyesight, deterioration of the brain, loss of muscle tone. A general and inexorable collapse of the edifice. The older you get, the more the genes veer and appear to not care. If you don't die of this, then you'll die of that. When you get past a certain age, I suppose, it becomes misleading to say He died of cancer or heart disease. Really, it's old age.
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  3. desi Valued Senior Member

    I've been told our body is like a new car. There isn't much you can do to make it better but there is all kinds of things you can do to mess it up. Maybe eating fast food is like putting sugar in the gas tank. Maybe some people's engines are made to run best on different types of fuels.

    Sure genes play a role. But you can't discount a toxic or healthy environment.
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  5. ElectricFetus Sanity going, going, gone Valued Senior Member

    and just like a car it will break down and rust, unfortunately we do not yet have the medical technology to replace all or even most of the broken down parts, someday, someday soon we hope we will have the technology such that with enough money you can get your body back into showroom condition no matter how many miles you have clocked.

    Aging is caused by multiple pathways at once, lest of which is that we simply were not evolved to last indefinitely. Organs begin to
    degenerate primarily because biochemical pathways that repair and optimize your organs when you reach your prime begin falling out of alignment afterwords, evolution does not care you have already bred, now die and make room for your successors.

    True what you eat can affect your life span, but looking at the average lifespan of all first world countries and you will see what you eat on average is only going to add or subtract a handful of years, primarily how long your body lasts is a function of genetics. Its not just a collection of genes that kill you after your prime its also that the gene that keep you alive simply were not designed to do so forever: we are simply lacking the genes necessary to maintain homeostasis for centuries! We would need totally new biochemical pathways and feedback loops to be able to operate at our prime for centuries.
    Last edited: Mar 1, 2010
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  7. cosmictraveler Be kind to yourself always. Valued Senior Member

    I just enjoy knowing that everyone will eventually pass away for one reason or another. You can try to make yourself anew but eventually something will kill you. It is comforting to know that no matter how rich you become or how poor you are that we all will succumb to death. You can't take anything with you that you've accumulated either, which makes having allot of stuff here and now pretty useless because you are here only for less than 100 years and that's nothing in geologic time.
  8. ElectricFetus Sanity going, going, gone Valued Senior Member

    The rich will live longer fuller lives then the poor, I don't think that very comforting.

    Maybe, maybe not, if mind uploading ever becomes possible all your memories and personality could be retained and emulated in a computer forever, outlasting the earth, the sun, etc, or well as long as the universe lasts, perhaps technology will develop ways to circumnavigate the end of the universe even by creating new universes, orchestrating existence in higher dimensions and existing beyond the limits of time. Short answer is that immortality is at least hypothetically possible.
  9. desi Valued Senior Member

    A friend of mine told me the money going into cloning research is so some old fat cats can get some brand new cloned parts of themselves when the need arises. I guess wealthy folk don't care for dealing with the possibility of transplant rejection.
  10. ElectricFetus Sanity going, going, gone Valued Senior Member

    Quite possibly, though in a socialized medical system, organ pharming in which GM animals are used to grow humans organs, even organs made from stems cells from a specific person and thus having all the same immunomarks will be a privlage provided to all. Clones of people for organs is simply to unethical to be done, but a animal with clone organs is withing ethical limits for most.
  11. Fraggle Rocker Staff Member

    It's known as "the Law of Unintended Consequences." The way it's usually stated is, "You can never do just one thing." You can never predict the second-order effects of your actions.
    This is a very good spot to stop and contemplate the Law of Unintended Consequences. What would be the second-order effect of immortality?

    Well, if we all live forever, pretty soon there won't be any room in the ecosystem for our offspring. We'll have to stop reproducing. And then what will happen? Genes will no longer "automatically accumulate" because there will be no more natural (or unnatural) selection. We'll stop mutating because there won't be any more "next generation." There won't be any people born with unusual characteristics that might make them better adapted to the world of the 31st century or the 41st century or the 6,827,905th century.

    In other words, we age because if we didn't our species would die out the next time something changes our environment drastically.
    Do you see that happening now? I don't. When one of the three or four oldest people on earth dies, it's a major event and the newspapers cover it in great detail. I agree that they're never poor farmers in Mali, but they're almost never rich people either. They're usually ordinary working folks, not even upper-middle class.

    Rich people don't take good care of themselves. They indulge in smoking, drinking, eating whatever they feel like, and they live highly stressful lives.
    "Hypothetically possible" is redundant, not oxymoronic.
  12. ElectricFetus Sanity going, going, gone Valued Senior Member

    Assuming we won't be able to evolve in a pseudo-lamarckian fashion, with technology we could adapt or "evolve" faster then anything natural Darwinian evolution could do. Why breed and die when you can just upgrade, copy and paste?

    I was not talking about now nor about was a talking about natural life spans.

    and when technology comes into being that can extend lives they will be the first buyers.
  13. francois Schwat? Registered Senior Member

    That's true, yes. But it almost doesn't matter how well you take care of yourself. Compared to someone who takes okay care of himself, you might add on, what, five years or something? Your time is limited and it doesn't matter what you do. That's why I can't understand the intense scorn that people have for smokers in the US. It's usually some fat woman or guy who gives an evil sneer to someone who's smoking in a public place. You're going to die anyway, you might as well have a good time. "Ooooh! You might have an extra year or two if you don't smoke!"--but if you dont' die of esophagal you might die later with something more painful.

    That might be true. But I think it's more likely that it's because of a limitation that stems from how we historically changed our genes. Wouldn't it be better and serve the same purpose if we never aged, but then at some time after our children reached maturity we dropped dead? What's the function of aging? There is none. It's just a byproduct. It's not something we evolved. It's a limitation of our evolutionary history. You see that a lot in evolution.
  14. kmguru Staff Member

    One word: Telomerase
  15. S.A.M. uniquely dreadful Valued Senior Member

    Seriously? I haven't been keeping up with his BS.

    Evolutinarily, keeping alive long enough to reproduce has always been more important than living longer. Once you've reproduced what is the reason, if any, for your body to continue consuming resources? But we are living longer and longer with more and more ageing populations. So clearly we are "beating" that theory some.

    As to why we age, thats no mystery. Cumulative continuous damage overcomes the ability to repair it. We age because we live.

    How to live longer as a species? Have less children. Take care of your health.
    Last edited: Mar 2, 2010
  16. ElectricFetus Sanity going, going, gone Valued Senior Member

    Or you could die a slow painful death of lung cancer at 30 from smoking. Its hedonism now at the risk of death soon, or moderation and optimizing for a long life, the choice is yours, though I do respect thous that live fast and die fast, sky divers for example when their times comes they respect it, they live for that rush and if the dive goes bad oh well.

    Evolutions is rarely so perfect. After you breed enough times it does not matter what happens to you as with each child there is increasingly limited return in gene proliferation not to mention that statistically disease or predation naturally would have killed you off with an average lifespan of 30-35, in cave man times living into your 40's was dam old. As such evolution has only design you to make it that long and only that long, it has not evolve homostatsis mechanism to keep you alive longer, as such you fall apart just like a car does post its warranty. It will take evolution much longer to keep extending our life spans naturally as people reproduce at older and older ages. Of course technology could do what takes evolution thousands of years in decades.
  17. Abscess Registered Senior Member

    ^ this. Replicative senescence ftw and implicated as a requirement in the proliferation of cancer. If you could have complete control of telomerase, I'm certain you could control the length of life.
  18. jonte92 Registered Senior Member

    thats very true,we dontyet have manufacturers of human spares
  19. Pathfinder Registered Senior Member

    I don't know why this myth persists. Maybe because it offers such a simple explanation for aging.

    The following is from (Toussaint, 2004). They are in vivo observations. In vitro observations, such as those used by Hayflick himself, are quite unreliable bacuase they do not provide the complex metabolic environment that the cells are in.

    There is some evidence that telomeres shorten in some tissues such as skin, but this hasn't been linked to aging. Donor age doesn't seem to correlate with telomere length and old people can have long telomeres. There is also evidence that somatic skin cells can increse their expression of telomerase when needed for e.g. regeneration.

    Cells undergoing replicative senescence usually have many thing wrong with them in addition to eroded telomeres, indicating DNA damage. Telomere length is used as an indicator of DNA damage as well. So it seems that the cause of replicative senescence is DNA damage and shortened telomeres are just a byproduct, possibly a way to prevent the cell from going cancerous.

    Nobody knows what fundamentally causes aging. But we know enough about the causes so that we can start doing something about it.

    Here you can read a little bit about that:


    (I can't post links yet :bawl

    Please Register or Log in to view the hidden image!

    Telomerase is not just involved with telomeres. There are numerous other jobs for it as well, so monkeying around with it is probably a bad idea. Here's something about that:

  20. ElectricFetus Sanity going, going, gone Valued Senior Member

    telomers are no he only reason for aging.
  21. Hercules Rockefeller Beatings will continue until morale improves. Moderator



    Contrary to what many people on interweb science forums think, it’s not merely a matter of fiddling with telomerase expression. Upregulating telomerase in cultured cells can induce effective immortality, but this does not extend to whole vertebrate organisms. I don’t have the reference at hand but upregulating telomerase in mice only conferred about a 10% increase in lifespan in some mice but carried the risk of increased incidences of cancer leading to a decrease in lifespan for the majority. That’s not much better than simple calorie restriction (for the ones that survived to old age, that is).

    The reason is that there is a very complex genetic control of aging involving interplay between a number of genes (not merely telomerase), all of which are working together to kill us after a certain period of time. We can influence some of the epigenetic and environmental aspects of the aging process, but we can’t escape the fact that we are genetically programmed to die.
  22. siledre Registered Senior Member

    I have a feeling aging is caused by parts getting worn out, that's my theory.
  23. ElectricFetus Sanity going, going, gone Valued Senior Member

    Exactly! there are 3 mechanism at work in our aging, homeostasis mechanism which were evolved to last only long enough, deleterious genes that will cause those homeostasis mechanism to fail after reproductive prime and finally the lack of homeostasis mechanism for indifferent survival.

    Telemeters are part of the first certainly as they are vital to our development and loss to telemerase would qualify for the second, but last is simply that we lack the mechanisms for near infinite life spans, say for example if we were to live for thousands of years we would build up toxic metals like mercury in our body because of we lack of mechanism for removing them, we have nothing to protects us from several hundred to thousand of years of ingestion.
    Last edited: Apr 8, 2010

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