> an entropy catalyst"
should be "anti-entropy catalyst", yes?
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)
 As opposed to there being some biological effect that you could try to 'turn off'.
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.
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).
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.
"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.
Physics Makes Us Age, Not Evolution
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.
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.
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).
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.
"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.
More likely is that immortal monkeys don't make evolutionary sense given the energy requirements.
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.
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.
So sci-fi stasis had it right all long.
Biggest problem is that water expands when frozen and bursts the cell walls D:
How does that follow? Compare with "Measles is a natural process that can be reduced to nanoscale viruses -- and not a disease."
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.
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.
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.
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.
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.