I believe that someday technology will be advanced enough to make aging be "cured" and people will achieve immortality and have a young appearance forever. However even if their brain remains biologically young I was thinking if people would run out of memories after they lived for hundreds of years. Could a 200 - 300 years old person remember events in their childhood and teen years or would they no longer remember? If not why?

It is normal for people have memory problems with aging but what if become possible to live so long and have a "young" brain for centuries?

  • $\begingroup$ Also, related. $\endgroup$ Commented Oct 16, 2021 at 15:25
  • $\begingroup$ I would offer that at just over half a century, my cognitive abilities are relatively unimpaired, but my earliest memories have thinned and in some cases, entirely lost aspects of themselves. Those dark caves of my mind are full of disconnected images, scents and sounds with none of their original context. I remember my mother's perfume and her smile, but not the moment when I smelled or saw them. Multiply this out to centuries instead of decades, and even those single-sense treasures might be gone. Family heirloom photo albums would come back into style. $\endgroup$ Commented Oct 16, 2021 at 15:37
  • $\begingroup$ This question is narrowly focused on memory while the proposed duplicate asks about the effects on the brain and consciousness in general. The second proposed duplicate is much more similar in scope, however, 5 years is a long time when it comes to neuroscience. Considering that old questions rarely get new answers, I think that this question should not be closed and the OP should get a chance to get answers based on the most recent research. $\endgroup$
    – Otkin
    Commented Oct 16, 2021 at 16:22
  • 2
    $\begingroup$ This does not seem to be a Worldbuilding question. It's really more neuroscience than anything else, although I doubt it's on-topic on that forum as it's asking a what-if that would require altering the biochemistry that brains are based on. $\endgroup$ Commented Oct 16, 2021 at 17:11
  • $\begingroup$ Read the novel "Icehenge" by Kim Stanley Robinson. Among many other things, the problem of longterm memory for centuries-old people is touched. They have doctors and psychiatrists that treat people for this, and personality drift measuring, and the introduction of terms for thing like deja vu, but where a decades-old memory forcibly intrudes on the current consciousness, triggering all sorts of introspection for the characters. Both remembering too much and remembering too little are possible. $\endgroup$
    – PcMan
    Commented Oct 16, 2021 at 21:23

1 Answer 1


They wouldn't hit the max capacity in hundreds of years.

Human memory is fairly huge, estimated to be at 8 petabytes, enough to record 3 million hours which is enough to store around 300 years of video. It's hard to estimate exactly how that correlates to memory, but it's probably enough to remember a decent slice of your life.

In thousands of years you would likely start to hit the cap. The immortality process would likely already have methods to prune neurones and connections and replace them when damaged, and they'd either lose random memories or need to prune some aspects of their past.

Of course, how well you remember depends on how well you consolidate long term memories. I don't remember everything I did yesterday, and my mind likely dumped most memories of that as unimportant. Events decades or centuries ago will likely be quite hard to recall if a focused effort isn't made to remember them.

Some millenia old people would likely have the discipline to remember well the past, by working to consolidate key memories. Some wouldn't care, and would forget all but the strongest of memories that were repeated across their memory.

  • $\begingroup$ "enough to store around 300 years of video. It's hard to estimate exactly how that correlates to memory" Imagine a video where only 'events' rather than images are recorded & a single still image for the objects in those events (with the same stock image for common items like chairs (etc) used multiple times whenever the 'script' says there's one) is recorded just once elsewhere then extrapolated into the video, the same memory capacity that can keep 300 years of video might store a lot more than 3000 years that way, not saying that's how memory works but it's definitely not a video :) $\endgroup$
    – Pelinore
    Commented Nov 7, 2021 at 1:21
  • $\begingroup$ "Some // would forget all but the strongest of memories that were repeated across their memory" I have a few memories from early childhood that I still take out & dust off once in a while, as a result their now memories of memories & more like something someone told me about but their still there, you strengthen or duplicate a memory every time you use it (maybe a little of both) . which may leave less room for other memories if you have only a small memory capacity of course :) $\endgroup$
    – Pelinore
    Commented Nov 7, 2021 at 1:35

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