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>>> The person you are today doesn’t share a single cell with the version of you from seven years ago. (This is, of course, a generalization as some cells regen

>>> The person you are today doesn’t share a single cell with the version of you from seven years ago. (This is, of course, a generalization as some cells regenerate much faster and others a little slower.) No, that is not even remotely true. Most of the neurons in the central nervous system (the part of the body one could argue does the most of thinking) stay mostly the same from adulthood to death[1]. [1]: https://en.wikipedia.org/wiki/Neurogenesis https://en.wikipedia.org/wiki/Neurogenesis

joshuaturner 1y ago
ah man I really wanted to be a new person
- g0db1t 1y ago
  [dead]
- daxfohl 1y ago
  A body's atoms do completely recycle every 5-7 years though. 98 percent are recycled annually. Weird.
  - darkr 1y ago
    Incorrect
    - daxfohl 1y ago
      I thought so too, but it seems reasonable considering we're 70% water, much of it flowing and actively taking stuff out and around. Plus cells are apparently way more dynamic than is typically conveyed in high school bio (I think there was a quantamagazine article a while ago). So it's perhaps surprising that a body's atoms aren't fully recycled even faster than that.
      - gus_massa 1y ago
        IANAMD. IANAB. Let's guess anyway: The Ca in bones is probably renewed very slowly. C H O N very fast, in particular water. Na, K and Cl are very soluble and also get renew very fast. Some rare elements like I are probably reused a lot and renewed very slowly. I'm not sure about P, my hand waving is confused. Assuming a burger per day, we ate our weight in meat every few years, but I'm not sure if all the Fe is absorved in and exchanged for the internal one.
- malux85 1y ago
  Then just believe it, Abstract thing A you can never measure gives you joy and renewal Abstract thing B you can never measure holds you back and limits you The practical difference is zero or near zero, so go and be joyful and happy!
- scoofy 1y ago
  It doesn’t matter whether the cells actually change. The persistence of the self, and even consciousness itself, are very possibly an illusion.
  - jstanley 1y ago
    Consciousness is the only thing that can not possibly be an illusion. Whenever this comes up I have to wonder if half the people are secretly p-zombies and actually genuinely aren't sure whether consciousness is an illusion because they've never experienced it? I know that's not a very charitable take but I just can't see how any conscious being could imagine that consciousness could be an illusion! Consciousness isn't the illusion, consciousness is the audience!
    - pcthrowaway 1y ago
      The person above meant "the persistence of consciousness" Yes, we are conscious (or at least I am, I'm assuming y'all are too). But consciousness isn't static. My consciousness today is not my consciousness of 5 years ago.
      - sage92 1y ago
        Begs the question: by what metric are you using to track the change/staticity? I don’t see how one can concretely come to the conclusion of whether it changes or stays the same, when the presence of consciousness itself is a prerequisite of making that very claim
        pcthrowaway 1y ago
        Well if you believe there's something magical about consciousness I could see why you'd believe the same person's consciousness at different points in time is the same consciousness. If you believe consciousness is a function of sentience and self-awareness, and presumably that AI can one day be conscious (not saying it is right now), then I don't see how you can believe consciousness is persistent. If the AI is copied/moved to a different server, is it the same consciousness? Or in Star Trek when you get beamed up are you the same consciousness?
cwbrandsma 1y ago
That sucks, since I developed a neurological issue from Covid I could really use a refresh of my nervous system.
- dredmorbius 1y ago
  Be careful what you wish for. (With an understanding that where you are now undoubtedly sucks. My sympathies.)
LPisGood 1y ago
I once heard that this is an oft repeated myth, that neurons are not replaced throughout life. It seems to me to that what you said is true, but for some odd reason I have a recollection of reading a debunking of this. Does anyone know what I might be thinking of?
- chewbacha 1y ago
  They are just very very slow. It does happen but the turnover is not fast and certainly not every 7 years.
- mattkrause 1y ago
  It’s been very hotly debated for ages. At the moment, the consensus seems to be that some neurons[*] are occasionally born in adulthood (e.g., in the hippocampus), but there’s a lot less agreement on why or if this matters at all. It could be the remnants of a prenatal process or a neat method for providing “pointers” into memories. * In the brain itself. It is widely agreed that olfactory sensory neurons turn over every month or two, but they almost have to because they’re exposed to all sorts of junk in the air and wouldn’t survive a lot longer anyway.

joshuaturner 1y ago

ah man I really wanted to be a new person

g0db1t 1y ago
[dead]
daxfohl 1y ago
A body's atoms do completely recycle every 5-7 years though. 98 percent are recycled annually. Weird.
- darkr 1y ago
  Incorrect
  - daxfohl 1y ago
    I thought so too, but it seems reasonable considering we're 70% water, much of it flowing and actively taking stuff out and around. Plus cells are apparently way more dynamic than is typically conveyed in high school bio (I think there was a quantamagazine article a while ago). So it's perhaps surprising that a body's atoms aren't fully recycled even faster than that.
    - gus_massa 1y ago
      IANAMD. IANAB. Let's guess anyway: The Ca in bones is probably renewed very slowly. C H O N very fast, in particular water. Na, K and Cl are very soluble and also get renew very fast. Some rare elements like I are probably reused a lot and renewed very slowly. I'm not sure about P, my hand waving is confused. Assuming a burger per day, we ate our weight in meat every few years, but I'm not sure if all the Fe is absorved in and exchanged for the internal one.
malux85 1y ago
Then just believe it, Abstract thing A you can never measure gives you joy and renewal Abstract thing B you can never measure holds you back and limits you The practical difference is zero or near zero, so go and be joyful and happy!
scoofy 1y ago
It doesn’t matter whether the cells actually change. The persistence of the self, and even consciousness itself, are very possibly an illusion.
- jstanley 1y ago
  Consciousness is the only thing that can not possibly be an illusion. Whenever this comes up I have to wonder if half the people are secretly p-zombies and actually genuinely aren't sure whether consciousness is an illusion because they've never experienced it? I know that's not a very charitable take but I just can't see how any conscious being could imagine that consciousness could be an illusion! Consciousness isn't the illusion, consciousness is the audience!
  - pcthrowaway 1y ago
    The person above meant "the persistence of consciousness" Yes, we are conscious (or at least I am, I'm assuming y'all are too). But consciousness isn't static. My consciousness today is not my consciousness of 5 years ago.
    - sage92 1y ago
      Begs the question: by what metric are you using to track the change/staticity? I don’t see how one can concretely come to the conclusion of whether it changes or stays the same, when the presence of consciousness itself is a prerequisite of making that very claim
      - pcthrowaway 1y ago
        Well if you believe there's something magical about consciousness I could see why you'd believe the same person's consciousness at different points in time is the same consciousness. If you believe consciousness is a function of sentience and self-awareness, and presumably that AI can one day be conscious (not saying it is right now), then I don't see how you can believe consciousness is persistent. If the AI is copied/moved to a different server, is it the same consciousness? Or in Star Trek when you get beamed up are you the same consciousness?

cwbrandsma 1y ago

That sucks, since I developed a neurological issue from Covid I could really use a refresh of my nervous system.

dredmorbius 1y ago
Be careful what you wish for. (With an understanding that where you are now undoubtedly sucks. My sympathies.)

LPisGood 1y ago

I once heard that this is an oft repeated myth, that neurons are not replaced throughout life. It seems to me to that what you said is true, but for some odd reason I have a recollection of reading a debunking of this. Does anyone know what I might be thinking of?

chewbacha 1y ago
They are just very very slow. It does happen but the turnover is not fast and certainly not every 7 years.
mattkrause 1y ago
It’s been very hotly debated for ages. At the moment, the consensus seems to be that some neurons[*] are occasionally born in adulthood (e.g., in the hippocampus), but there’s a lot less agreement on why or if this matters at all. It could be the remnants of a prenatal process or a neat method for providing “pointers” into memories. * In the brain itself. It is widely agreed that olfactory sensory neurons turn over every month or two, but they almost have to because they’re exposed to all sorts of junk in the air and wouldn’t survive a lot longer anyway.