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Comment by esahione | Hacker News Reader

Inevitability to me is the Sun becoming a Red Giant. Aging is definitely not inevitable - hydras are a counterexample (and thus refute his claim).

He uses the same argument as Aubrey de Grey but reaches the opposite conclusion.

If aging is caused by the accumulation of mutations and 'wear and tear' then we can control it. All we need are properly placed stem cells derived from your 'unmutated' cells and taking care of the damage caused by our metabolism.

I mean: we have 37+ trillion cells in our body. To find a lot of them that haven't suffered any mutation shouldn't be hard. We could even take a billion cells and use the most common base for a given position - in the end it should lead to your original dna because each cell would have base mutations in random areas.

Or we could freeze a sample of DNA when we are young to ensure we have a non-mutated cell-line available for therapy.

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Absence of aging in hydra:

http://www.pnas.org/content/112/51/15701.abstract

"Here, we present compelling evidence for constant mortality and reproduction of Hydra using data from careful, large-scale studies over 8 y with 2,256 individuals."

But really, you only have to point to the germline to note that aging doesn't have to exist as a matter of basic physics. The germline, like hydra, regenerates itself - rejuvenation through proficient repair. If it didn't, we wouldn't exist.

Similarly for many species of bacteria. Some of them do age, but many do not, though once you go past yeast to bacteria you start to have definitions for aging that are quite distant from what it means in complex multicellular organisms like hydra or ourselves.

So thermodynamics and entropy is - and always has been - a pretty silly place to stand when looking at aging, as we can haul out any number of complex living systems that (a) don't age and (b) absolutely follow the laws of thermodynamics, just like all of the rest of us.

I believe this is probably a poorly written headline, probably not by the author of the article. I went into it thinking the exact thing you did, but the article doesn't actually argue anything about inevitability. A better headline would have been:

Physics Makes Us Age, Not Evolution

The whole argument needs tightening.

I hate to be the wikipedia poster here, but the entry on Biological Immortality does make for a good read in this context;

https://en.wikipedia.org/wiki/Biological_immortality

Yes to this. Not only could we find the correct original DNA sequence by statistically looking at a large number of cells- the fact that biology can't do that might explain why (almost) all living things age. If you can't error correct statistically, (and evolution can't since earth biology can't compare multiple DNA strands at once) then you have to prune the mistakes by reproduction followed by death if the new organism has defective DNA.

> Or we could freeze a sample of DNA when we are young to ensure we have a non-mutated cell-line available for therapy.

So we just need some light, paradox-correcting time travel for those of us that have presumably passed the point of freezing young-enough DNA. :)

I'd rather use software to error/spell check my genome, and slowly edit to improve over time with crispr. No need to focus on my genome at birth.

I really love the error/spellcheck analogy.

Thanks! I wish I could take credit, but I recall reading it in a passage about future tech possibilities in the book "Superintelligence":

https://www.amazon.com/Superintelligence-Dangers-Strategies-...

Oh, nice. I hadn't heard of this book before. Thanks for the pointer. I'll have to check it out.

;)

We could just use statistics.

Example: the DNA has 3.2*10^9 base pairs. We have trillions of cells. Even if each cell division introduced 1000 mutations, the cells would hit the Hayflick Limit at around 60 divisions. The last generation of a cell line would have 60000 mutations on average and the other cells less so.

It's nothing compared to the size of the DNA. I can't go through with the calculation right now but my guess is that it wouldn't take more than a billion cells to get to your birth DNA.

That part of my argument was just an easy way to deal with the writer's assumptions.

Also - we likely could correct most of the damage by sequencing only one or a few cells. Almost all human genetic variation is in a relatively small number of well known locations in the genome - if we assume mutations occur at random locations, we can fix almost all of them by looking at any reference genome.

If something is missing replace with frog DNA. Should not cause any problems.

Cool, I've always wanted to procreate without the pesky inconvenience of sex... ;)

I'm going to die from a bad implementation of bitcopy(). Great.

To be clear, you're arguing that hydras will outlive stars?

No. I simply gave a counter-example to a claim--thus the claim is refuted.

His claim is: all beings that are alive also age. The counter-example makes so that his argument is false (hydras are alive, but do not age).

I didn't claim that being alive means you outlive the universe. Because that would be false. Everything alive is subject to the laws of thermodynamics (need energy to keep up the entropy-fighting machinery)--no food, no hydra.

> hydras are alive, but do not age

The point is that a hydra that does not age is clearly violating the laws of thermodynamics; hence, eventually, they will age (as you pointed out).

No it isn't violating thermodynamics - it's not a closed system. Eventually they will die of hunger or, what is more likely, being eaten by a predator.

Nothing in thermodynamics says that it's impossible for a self-repairing system to continue to exist until it either runs out of resources or is destroyed by outside forces.

Hydra are not a closed system. They can lower their entropy at the expense of their surrounding

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