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Comment by nabla9 | Hacker News Reader

If you had full understanding of human cell and how they contribute to homeostasis, you could reprogram the cell to rejuvenate them endlessly without turning into cancer (many cancers have unlimited lifespan). You would also need to find ways to remove all cruft that gradually accumulates even in healthy body, like heavy metals etc.

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How do you know that you could? That’s the question! If we did understand biology perfectly it may be that we would then prove no organism can live forever and reproduction is the only way.

Reproduction doesn't create whole new cells from nothing (except in the ship of Thesius sense). It's existing cells getting reprogrammed to do new things.

Reproduction does result in new matrix/scaffolding being built but the cells build that (and can rebuild it if so directed).

Of course some things "we" care about exist exclusively in the matrix (configurations of neurons, learned behaviors, memories, etc) so that could well be a limit for those parts of the body where we care primarily about preserving the matrix.

Anyway my point is that "reproduction" doesn't create whole new life, it's just a continuation.

> Anyway my point is that "reproduction" doesn't create whole new life, it's just a continuation.

Then you're just arguing that we're already immortal, after all we reproduce, but I don't think that's what we're talking about when we talk about longevity. Longevity is the continued existence of a particular being, not its continuation through descendants.

The point is that a fundamental assumption that "reproduction" does anything that can't be done by regeneration is just a hunch that so far isn't actually supported by anything in microbiology. The existence of reproduction is irrelevant to the question.

Reproduction is not physically special. If it is physically possible to create a new organism with a longer lifespan than its parent (which it is), then it is physically possible to extend the lifespan of an existing organism. This may be impractical, but we cannot prove that no organism can live ≈forever, because it's not a physical impossibility. (Assuming a source of power remains present: it looks like the universe won't last forever, so we can trivially assert that no organism can live forever.)

> it is physically possible to extend the lifespan of an existing organism.

This is not at all guaranteed until we actually manage to do it. And that's exactly what we're discussing, you can't just say "but it must be possible". There's no rule of the universe that says it should, and given life has been around for 4 billion years and there's no single species (specially animals which is what we really should consider here if we're talking about human lifespan) that manages to live for more than a few hundred years, I think that's strong evidence that life is approaching a fundamental limit here. Someone else said "maybe that's enough" - well, why?? Maybe 100 years is already quite enough then??

Take the existing organism apart, fix all the problems, put the organism back together. No laws of physics prevent this, so by the totalitarian principle it's physically possible. Principles of engineering might make it impractical, and even if it is practical we might never discover how to do it, but it's possible.

Some cells are literally hundreds of millions of years old.

That’s not forever and it required a very specific environment, but biological degradation on that timescale can be effectively zero.

Because there's absolutely no reason to believe that's the case? Like I don't know what the point of this argument is: maybe it's impossible. Sure, great. Okay. But you know...let's actually find out, because it looks very possible if hard from our current vantage point.

> Because there's absolutely no reason to believe that's the case?

The fact we haven't seen an organism live forever is strong evidence that that's the case. You're the one making the case without any evidence!

I mean I also feel like people would be pretty happy with the average lifespan of a tree, or a Greenland Shark, etc.

Also, some few (fairly primitive) animals are "biologically immortal," for example, lobsters (which are motile and vaguely resemble us more than, say, sponges and jellyfish) don't experience senescence.

That being said, I think we have a long way to go if we want to make any progress at all, and I doubt I will live to see it.

You know what a chaotic system is, don't you? That goes for a simple double pendulum.

There is no "full understanding" of a complex system.

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