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Physics Makes Aging Inevitable, Not Biology (nautil.us)
102 points by dnetesn on May 12, 2016 | hide | past | web | favorite | 60 comments



This is the same kind of fundamental misunderstanding of physics that leads to arguments like "evolution can't exist because of the second law of thermodynamics". Living things are not closed systems, the inevitable increase in the sum total entropy in the universe has no bearing on their ability to repair themselves.


Yes indeed, and during the drunken biochemists' ball the suggested definition of life: "an entropy catalyst" wasn't the worst one (by far)


> drunken biochemists' ball

what's this?

> an entropy catalyst"

should be "anti-entropy catalyst", yes?


y'know how every university department has a yearly "retreat"?

The parent poster made an incisive reference to: "living things are not closed systems, the inevitable increase in the sum total entropy in the universe.."; and so it is. A living process maintains its own internal order at the cost of the entropy and energy of its surroundings. Life increases the entropy of its surroundings at a higher rate than in its absence. (of course so does fire, and that's why this is only not the worst definition)


I think the author's point is since aging is related to physics, you're facing exponentially increasing problems[1]. This will make it much harder to make progress against than the battle infectious diseases. (There were some similar articles a while back that focused on cancer specifically.)

[1] As opposed to there being some biological effect that you could try to 'turn off'.


It was also what I thought when I saw the title, but if you go through the write up, you'll see that that's not the argument here and what he's saying makes sense.

He's essentially talking about the imperfect cell division which leads to increasing amount of "errors" in average cellular structure over time, and that if this is the most important cause of aging, future studies should be focused at molecular level (which is typically the domain of physics). Here's an excerpt from the conclusion:

> That doesn’t mean there is nothing we can do. More research into specific molecular changes in aging is needed.


It's still handwaving from a twenty-thousand foot view, whereas the devil is in the details.

I don't see how his thesis addresses the very large difference in lifespans for different species, first and foremost.

Secondarily, although he addresses the body's repair mechanisms, I don't see how he puts a new limit on their capacity, unless I overlooked it, or unless he thought things like the Hayflick limit etc. perfectly address that (which it does not completely do).


I came here, to basically say the same thing. It seems folks do not realize the assumptions they are making. Fundamentals people fundamentals.


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.


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. :)


;)

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'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.


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


If these arguments are followed to their logical conclusion, biological life could not exist.

It's biology (and perhaps a bit of philosophy) that divides a parent from a child. The physics doesn't care that the cell is in contact with a separate brain. And for single-celled or asexually reproducing organisms, the division between parent and child is even less obvious, but those organisms still exist.


"If this interpretation of the data is correct, then aging is a natural process that can be reduced to nanoscale thermal physics" - this was utter crap. No wonder this guy is at a liberal arts college. You can't equate atomic force breakage to senescence. Without any scientific linkage it's like linking the sinusoidal pattern of seasonal temperatures to the amplitude of an alternating current. Welp, must mean that the basis of temperature is electricity right?

"But the sheer number of possibilities being put forward refutes the very possibility. They can’t all be the cause of aging." - Wrong, more likely it's a mix of all of them. You can cruise PLoS One and realize that most researches in this area realize that it's likely a combination of many underlying factors from other researchers' discoveries that contribute to aging.

One more thing, how does an open system become limited to the second law of thermo like a closed one?

Stay scientific Hoffman.


It's disappointing that this article doesn't address the various animals with a degree of biological immortality (eg jellyfish, lobsters). I'm not convinced that the laws of thermodynamics make (human-scale) aging inevitable and insurmountable if there are several unrelated critters who have managed it.

More likely is that immortal monkeys don't make evolutionary sense given the energy requirements.


Another article in the same Nautilus chapter addresses some of the variety of aging styles in other plants and animals (and concludes that aging is not in fact inevitable): http://nautil.us/issue/36/aging/why-aging-isnt-inevitable


Lobsters are probably on the way out of the possibly immortal and into the negligibly senescent category. They were only in the former category because there was no way to measure the age of an arbitrary sample of lobsters retrieved from the wild. Researchers did find a way to measure lobster age reliably a few years back, so data will emerge on their life spans over the next few decades. It isn't a well populated or well funded area of study, so results tend to lag.

http://www.sciencemag.org/news/2012/12/tree-rings-lobsters


Simple analogy: would it be possible to design a digital hardware/software robot (and set of tools), such that the robot could:

1) build/maintain the tools it needs

2) use tools/knowledge/skill to repair/rebuild/replace its parts, good-as-new

3) transfer it's software from the old parts to the new parts when necessary

4) achieve immortality

If so, one needs to argue why this analogy could not hold for biological life, why any underlying hardware or software cannot in principle be replaced/repaired/migrated to maintain the immortal being.

Obviously this avoids arguments over the self/persistence of identity (ship of theseus), but it's not directly relevant to the article.


It is true. The Von Neumann Universal Constructor is one.


The point seems a bit fatuous, a bit like arguing that a modern desktop machine isn't turing complete because there is a finite amount of memory.

No, we can't reverse entropy, or avoid damage to our bodies. But that says nothing about whether we can slow it down, or do enough self repair, to consider these problems practically solved.


This article is complete and utter nonsense. Anything can be made to last arbitrarily long, given enough external resources/energy and the ability to replace its parts.


Taking the strong computationalist view here: You need to consider the complexity-class of the operation for a claim like that to be meaningful. Human beings might be outside of anything tractable beyond whatever class growing a human being is in.


Not true. Entropy wins, eventually.


>They found that the shape of the survival curve remained essentially the same, but it was stretched or contracted as the temperature was changed. Creatures raised at lower temperature enjoyed a stretched survival curve, while worms exposed to higher temperature lived shorter lives.

So sci-fi stasis had it right all long.


We knew they were right way before that: chemical reactions happen more slowly when colder. If you freeze your body nothing moves within your body and thus you don't age.

Biggest problem is that water expands when frozen and bursts the cell walls D:


The obvious solution is to replace all the water in your body with something else.


Brawndo, obviously


> If this interpretation of the data is correct, then aging is a natural process that can be reduced to nanoscale thermal physics—and not a disease.

How does that follow? Compare with "Measles is a natural process that can be reduced to nanoscale viruses -- and not a disease."


How about, "DNA damage from radiation is a natural process that can be reduced to nanoscale particle physics." This article is surprisingly fluffy. It doesn't mention SENS at all, which addresses some of these points.

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


Except there are already known (rare) people who seem to age much much more slowly from superior genetics.


One example of immortality in humans is the egg cells. http://www.cam.ac.uk/research/news/egg-cetera-1-the-immortal...


Entropy is the driving force of the universe and the one that rules life and death, it's particularly interesting the relationship between the drop in the internal temperature and the stretched survival curve...

I suspect that something similar is the cause for the "time dilatation" effect of living things moving at high speed, the rate at which entropy advances should reduce and hence the reduced decay rate. Still looking for a speed-entropy relationship though.

Anyway, loved the reading. I have entretained similar thoughts about the relationship between entropy and death for some time.


Article doesn't address the question of whether a short lifespan is adaptive (i.e. whether current 'limits' on lifespan have nothing to do with systematic barriers). One reason for this would be the need to pack in more generations under conditions where rapid change is necessary in order to compete.

The research on extra copies of tumor-fighter TP53 in elephants suggests that when the conditions are right, senescence can be rolled back. The fact that mammoths are extinct and elephants are next could mean there are downsides to this evolutionary strategy.


Mammoths are extinct and elephants are "next" because of human hunting.


Another way to say that is that hominids with shorter lifespans out-evolved them. Today elephants are threatened more by habitat competition with us than demand for ivory or meat. Farmers at the edge of the wildlife parks in india and africa don't want to kill the elephants, they're protecting their crops. Orangutans are in the same boat.

Another perspective is that long cancer-free lives turned the pleistocene megafauna into meat repositories for any smart, mobile team predator, and that if primates didn't use the mammoths as a safe way into the arctic some other pack animal would have (wolves, for example).

Causation is hard to model in coevolution. People who study e.g. bacteriophages use the term 'domestication' to describe how coevolution partners influence each other; if you're going to read one paper about this read the one about bracoviruses and butterflies, it's eerie.


And yet my refrigerator keeps my food cold.


The quest for immortality is the ultimate selfish narcism. The species is already immortal and will do fine without you. An almost identical human will take your place when you're gone and that human will have almost identical thoughts and feelings as you. Why does the species need to keep an old atrophying individual around? What's the point?


> The quest for immortality is the ultimate selfish narcism. The species is already immortal and will do fine without you.

Doing science is the ultimate narcissism. The universe operates according to scientific laws, and will do so just fine whether or not you understand them.


Is there a known explanation of how a newborn gets its biological age reset, given that the newborn starts from the cells from its aged parents? If the answer is not understood, it may be easier to research this instead by studying say zygote formation.


Systems Thinking and simulations show why aging is such a great idea. Death energizes reproduction and renewal so that no particular pattern can dominate and experimentation and adaptation are organic components of continuation.


No...If you can change all the atoms in your body. U can probably live longer...


> No...If you can change all the atoms in your body. U can probably live longer...

Indeed, and if we declare each apparently dead person to have transferred his or her identity to someone born just a few moments before, then no-one will ever die.




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