8 ms·

It's very likely that aging is driven by some kind of scheduled gene program. It makes perfect sense to phase out individuals from a group-level selection point

• kkoncevicius 1y ago
  This would be an optimistic scenario and introduce a possibility for the "scheduled gene program" to be controlled or turned off. The current thinking in the field seems to favour the idea that aging is a complex combination of programmed changes, stochastic damage, as well as various adaptations to help cope with the damage.
  • piombisallow 1y ago
    Menopause is also an obvious planned partial shutdown (vs males who can reproduce when they're 80) and we're no closer to "curing" it, turning it off.
    • rowanG077 1y ago
      I don't think there is much interest in stopping menopause. So you are right we can't cure it. But I don't think that's a good indication.
• NoOn3 1y ago
  Maybe. But why in this case do we not see bugs and failures in this program, i.e. no one lived 5 times more than the average or did not live forever at all, for example? I'm not making a statement, just a guess.
  • hyperman1 1y ago
    You could say this woman is immortal. Or at least her cancer is. https://en.m.wikipedia.org/wiki/Henrietta_Lacks https://en.m.wikipedia.org/wiki/Henrietta_Lacks
    • NoOn3 1y ago
      I'm not a biologist. But it seems to me that this is at the level of one cell. Yes, a cell can become immortal, but cells live much less than a whole person. Over the course of a person's life, many many cells change. And the program for human life, rather than individual cells, is perceived differently.
  • piombisallow 1y ago
    Height is controlled by genes too and you don't get people shorter than 0.5 m or taller than 3 m
    • JPLeRouzic 1y ago
      True, but one guy was 272 cm (8 ft 11 in) tall: https://en.wikipedia.org/wiki/List_of_tallest_people https://en.wikipedia.org/wiki/List_of_tallest_people And another was 76cm high: https://en.wikipedia.org/wiki/List_of_people_with_dwarfism https://en.wikipedia.org/wiki/List_of_people_with_dwarfism
  • tgv 1y ago
    Because the whole system is quite resilient and self-repairing, and probably requires a great deal of consistency between the various genes? Aging is quite fundamental to life, and a "bug" in that area would almost certainly cause severe problems in other areas, probably death. Cancer might be an example. And systems of many components tend to narrow the standard deviation of the composite. But that's just guessing. The article might not even have found something profound, but a life-style effect. On the one hand, we're living long (historically speaking), on the other hand, we have unnatural habits.
    • rowanG077 1y ago
      aging doesn't seem fundamental to life to me. There is known complex life that doesn't age. I expect age is a huge driver of evolution in many cases so it makes sense that most life has it.
      • fc417fc802 1y ago
        You have that backwards. In many cases aging hasn't noticably impeded evolution so it hasn't been selected against.
        • rowanG077 1y ago
          You misunderstood what I said. I'm saying not aging does clearly impede evolution. This is not some exotic idea, it's be brought forth before: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1558-5646.1957.tb02911.x https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1558-5646....
  • landl0rd 1y ago
    Because the odds of something 5x the average that's more or less normally distributed are really, really low. It's the same as how although you can occasionally get a "natural" person over seven feet tall, it's very rare. Most really tall people have gigantism or some other form of pituitary abnormality, and I believe every recorded person to break eight feet has had such an abnormality. It's like asking why we've never had someone with 500 IQ. There's a hard limit where anyone with enough of a mutation to enable that would probably also not survive long at all. And indeed with the height thing we see a lot of super-tall people dying younger due to cardiovascular strain and other issues. You get the picture.
    • DevelopingElk 1y ago
      It's because age isn't normally distributed. The annual odds of dying go up by a factor of 2 every 8 years. This gives tighter bounds on age than a normal distribution would give.
  • kkoncevicius 1y ago
    Such arguments go both ways. For example, if aging is accumulation of damage and not programmed, then why don't we see lucky people who live 5 times longer. Also how come the patterns of aging are so similar between individuals and even between different species (wrinkly skin, grey hair, fragile bones).
    • abeppu 1y ago
      But aren't there a lot of processes that could drive accumulated damage that are hard to avoid (so you can't realistically get lucky)? E.g. if metabolic processes produce harmful products in low quantities that build up ... How would you possibly survive many decades without doing at least a certain amount of metabolizing food etc?
    • blargey 1y ago
      How do you propose someone would "luck out of" the wear and tear your body undergoes just to function? It's accumulation of damage to the very systems that work to prevent and repair damage, leading all organs to accumulate the damage they would have hidden by fast repair in "youth". It's unavoidable and accelerating by definition, and that reflects what we observe in aging. The "patterns of aging" you describe are, again, definitionally just what happens when the same organs built and functioning the same way across species undergo their respective failure modes. It makes more sense for all skins to exhibit the same signs of aging if they're all just wearing out the way "skin" does, rather than being attacked by species-specific "age limiter" processes artificially enforcing lifespan limits. Why would something like skin even need to decay at all, when it's basically unrelated to aging-related death?
    • crinkly 1y ago
      Think this is a statistical thing. Your body is made of lots of cells. But one exceptional one wouldn’t outlive the whole system’s failure. You’d need a hell of a lot of cells to survive that long.
  • csallen 1y ago
    Lots of models could explain this. For example, let's say it's not just one program, but thousand of programs running in your body, trying to get you to age or die. The chances that all of them bug out would be astronomically low.
    • dotancohen 1y ago
      But there have been astronomically high qualities of humans produced, none of which have shown this phenomenon.
      • csallen 1y ago
        Combinatorics can make things astronomically unlikely. Imagine the "aging program" bugs out 1 in 100 times, a pretty high failure rate. However, imagine the program runs in 10 systems in the body, and success in any one of these systems is enough to age and kill you. The body is quite fragile after all. If this were the case, then in order to not age at all, a person would need not just a 1/100 event to occur, but a (1/100)^10 event to occur. That's 1 in 100,000,000,000,000,000,000. In other words, one in a hundred quintillion. A hundred quintillion is about 840 million times higher than the number of humans who have ever lived, which is 120 billion.
        • dotancohen 1y ago
          Serious question. There are biblical accounts of people living hundreds of years. For people who like to find scientific explanations for biblical stories, is this plausible?
          • fc417fc802 1y ago
            No, because the underlying mechanism of intentional aging (as opposed to incidental) isn't plausible. The top level comment is pure fantasy. There's extensive scientific research on the subject of aging if you care to sink time into reading about it. Consider one of the many examples of embedded systems that suffered from subtle bugs that were dependent on environmental factors after they were left running for too long. The official manufacturer provided solution was to reboot (ie there is no solution). Now imagine someone in a comment section somewhere proposes the idea that these bugs are actually intentional program features. That's the scientific level this discussion is at.
  • oneshtein 1y ago
    Because those will need 5x more time to become adults.
  • 0xcafefood 1y ago
    If you want to see that idea explored in art, I highly recommend the movie "The Man From Earth."
• munchler 1y ago
  Is there convincing evidence for group-level selection in evolution at all? I read enough Dawkins back in the day to be skeptical of such claims.
  • mewpmewp2 1y ago
    Intuitively it seems like a logical selection to happen though. One of the reasons why all of the hierarchies have evolved, why some are leaders, why some are inventor minded, and why most people are like most people.
  • piombisallow 1y ago
    Yes, it's widely accepted that you have variable proportions of individual vs group level selection depending on circumstances.
  • notahacker 1y ago
    Depends what you mean by "group-level". A large part of Dawkins was pointing out that many of your individual genes had a very large stake in wanting your nieces and nephews to survive, as there was a high probability those genes were also present in the niece and nephew. Which is actually a pretty good reason for something like menopause to get programmed in. A proto-human capable of getting pregnant into her 60s would produce more offspring, but if accumulated damage meant they (and she) rarely survived the pregnancy, that could be less beneficial to the family group (including numerous relatives other than direct descendants) on average than having her switch the capability off and live another generation (but not many more generations, because then there's a lot of infertile people competing for food, and your tribe only needs so much accumulated wisdom)
• jebarker 1y ago
  Life expectancy much longer than 40 is a modern thing for humans though. So where would the over 40s schedule have come from? Or do you mean the schedule basically says: once you hit 50 start falling apart?
  • kkoncevicius 1y ago
    The average life expectancy was low because of more deaths during childhood and wars. But the natural lifespan was more or less the same as it is today. For example, take a look at famous philosophers or politicians from Ancient Greece. Majority of them lived to about 70-80 years of age.
    • jebarker 1y ago
      Good point. I realize that I was thinking of average life expectancy and that was biased by high child mortality until recently
  • dyauspitr 1y ago
    Life expectancy was heavily skewed by under 5 mortality rate. There were a lot of people living to old age.
  • abeppu 1y ago
    People keep repeating this, but my understanding is that low overall life expectancies historically were substantially about high infant mortality. If you made it out of childhood, your chances of living to be "old" were decent. It's not that the program used to say to start decaying at 40, it's that other exogenous forces would stop a lot of people from getting to that part of the program.
  • adamors 1y ago
    No, it’s not a modern thing, you’re conflating average life expectancy at birth with how long people lived in general. > Back in 1994 a study looked at every man entered into the Oxford Classical Dictionary who lived in ancient Greece or Rome. Their ages of death were compared to men listed in the more recent Chambers Biographical Dictionary. Of 397 ancients in total, 99 died violently by murder, suicide or in battle. Of the remaining 298, those born before 100BC lived to a median age of 72 years. Those born after 100BC lived to a median age of 66. (The authors speculate that the prevalence of dangerous lead plumbing may have led to this apparent shortening of life). https://www.bbc.com/future/article/20181002-how-long-did-ancient-people-live-life-span-versus-longevity https://www.bbc.com/future/article/20181002-how-long-did-anc... Just one source
• Qem 1y ago
  Perhaps not a phase-out program, but a progressive shut-down program, as a trade off between peak performance and total lifespan, where the characteristic patterns of ageing is what allowed humans to live much longer than other animals around the same size. Similar to the idea in this comic: https://www.badspacecomics.com/post/the-suit https://www.badspacecomics.com/post/the-suit By this logic, as a hedge against sudden death around ~50, the human body start cranking down the output of its diverse subsystems by then, to maximize operacional life, just like NASA engineers from time to time turn off instruments in the voyager to keep it operational against the odds. This is what we call ageing.
  • rootingforroots 1y ago
    Left me shivering.
  • pinkmuffinere 1y ago
    I think this argument only makes sense on the surface level. If it was the case that humans hit some hard limit to growth (perhaps running out of 'room' to grow, or losing the ability to process new energy, etc), then I think it could make sense to do this sort of 'graceful decommissioning' behavior, which we'd come to know as aging. But is there a hard limit we hit, aside from the aging process itself? None is obvious to me. What limitation is our body pushing off by 'choosing' to age, instead of continuing as normal? Edit: Regardless of the validity of the argument, I loved that comic, thanks for sharing.
    • PaulHoule 1y ago
      It's commonly thought that if your cells kept dividing the way that they do when you're young and they accumulated genetic damages you'd get cancer more often.
      • Teever 1y ago
        That isn't a satisfying answer because humans can obviously generate germline cells that don't suffer from this issue. So the question becomes why can't somatic cells repair themselves to be as healthy as germline cells?
• petters 1y ago
  I don't think it makes perfect sense. For one, group selection isn't widely accepted by evolutionists.
  • piombisallow 1y ago
    Yes it is: "Group selection, which was once widely rejected as a significant evolutionary force, is now accepted by all who seriously study the subject." (https://pmc.ncbi.nlm.nih.gov/articles/PMC3110649/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3110649/)
• grishka 1y ago
  My hypothesis is that it's just the continuation of the development program that starts with conception. It just turns self-destructive at some point, because natural selection didn't do anything about that because when humans were living in caves, no one lived to these kinds of ages anyway. So, to rejuvenate the body, you would have to find where the current state of that program is stored, and overwrite it to a younger one, as if using a debugger. So far there are two promising developments about that: Michael Levin's research about bioelectricity, and Harold Katcher's research about exosomes (he seems to have abandoned it, but other people are picking up).