So I’m trying to create a race of alien that lives for 600 years but I need them to have the memory space for all that time. The human brain can hold approximately 300 years worth of memory and that is fine since humans don’t live over 100 very often. These aliens would have memory space for 600 years-1000 years and they wouldn’t have difficulty remembering things that happened 200 years ago. I figured I would also have time move faster to them to make sure they don’t go insane but just like I am 28 and remember something I did when I was 24; I want them to be 650 and remember something when they were 435. What would have to be different about their brains. They would be basically humanoid.

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    $\begingroup$ Related: what-is-the-limit-of-a-humans-memory-if-immortal, the answers are informative but probably not a duplicate (particularly this one). Welcome Max. Please take our tour and read-up in the help center about how we work, enjoy worldbuilding. $\endgroup$ Nov 7, 2021 at 16:38
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    $\begingroup$ "The human brain can hold approximately 300 years worth of memory..." Support for this claim? And what actually IS memory? Does the memory content of the brain of say a 50 year old PhD who speaks several languages, plays a number of musical instruments, &c differ from that of Joe Average, or Jill Least-Common-Denominator? $\endgroup$
    – jamesqf
    Nov 7, 2021 at 17:59
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    $\begingroup$ Might be worth noting that memory recall in humans is not like a recorder. People "remember" things incorrectly and even fabrications all the time. They recall memories spontaneously, sometimes triggered by emotion, smells, context, etc. They try hard to memorize data and only succeed by persistent repetition. These phenomena seem to occur regardless of timeframe between the event and the recall. That said, where did you get this idea that the human brain can hold "300 years of memories". What that could possibly mean, clinically, is not sensible at all. $\endgroup$
    – user458
    Nov 7, 2021 at 19:10
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    $\begingroup$ Can't your aliens just ... remember? I mean, for the sake of your story, your aliens remember that event from 500 years ago, or whatever. Does how this alien memory works actually matter? If yes, how? $\endgroup$
    – user458
    Nov 7, 2021 at 19:14
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    $\begingroup$ Please read this article scientificamerican.com/article/what-is-the-memory-capacity $\endgroup$
    – Max
    Nov 7, 2021 at 19:37

2 Answers 2


After reading the article I realize a large misconception you have. Instead of 300 years of memories it is 300 years of television shows. And that's a big difference. Humans don't remember everything they experience, more like 15-22% of events that have happened recently. Not the entire experience, but that it happened. But we'll ignore that. If you remember 22% of everything you ever do (which is incredibly unlikely) you will still be able to store around 1350 years in the human brain.


Data compression. Adjust compression ratios, compression/decompression speeds and data loss as needed.

There are a few riffs on this that come to mind.

Maybe these aliens have tiny brains and superb data compression/decompression, which is fine until they take some brain damage, at which point the poorly compressed, raw storage human brain is better. Or vice versa.

Maybe compression/decompression is actually what goes on in our brains when we're searching for old memories. And so aliens with superb compression ratios but slow decompression are a bit like old people; able to remember details from years ago, but not the best with where they left their spaceship keys.

Or their algorithm is lossy in a very specific way, leading to some common psychological blind spot or social weakness.


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