The headline's premise does not square with the fact that there are organisms that don't age and whose life span is only limited diseases, accidents and predation.
That strongly points toward a biological reason for aging. I mean, sure, the heat death of the universe is inevitable, but that is not even remotely on the same time scale as the life span of complex organisms.
The author mentions in a comment that he didn’t write the headline (as is so often the case). His original headline (“Aging: where physics meets biology”) is much less controversial.
This is why I take issue with the way link aggregators handle title rules. The title of a popular article is usually written by someone other than the article's author (by a headline writer instead) in order to provoke more of a response. I think we should make an effort to reflect the content of the article, rather than take the misleading headline.
Whether you take issue or not is irrelevant. It works, or it wouldn't be done. The real world sucks. I mean it's the same reason we are still, in 2018, using JavaScript for large application development. Best just get used to it.
Evidently it does not work for GP. “This is what’s done” is hardly a counterargument to “I think we should change this.” It’s even weaker of a counterargument than “I actually like how it is.”
It wasn't a counterargument. It was merely a statement that one should not underestimate the momentum of an approach that is effective. It works well and is therefore unlikely to change.
Let us hope that through his HN comments ashelmire can fight the tyranny of linkbait titles.
I’m not arguing about whether it works for the people making the headlines. It obviously drives up clicks. But it does not work for places of discussion like this, where you have people arguing with the title and we care about discussion and meaning, not about the number of clicks they get.
Maybe the headline is somewhat flawed, but objects with negligible senescence are discussed in the article. According to the article the only difference between organisms with and without negligible senescence is whether there is a possibility for damage to accumulate.
Aging is a “planned” process, damage is just damage. Shortening telomeres with reproduction, cell senescence, loss of reproductive viability are not damage, they’re age related. UV light knocking a base pair out of a whack is damage.
If you live long enough, you will accumulate damage even in the absence of aging. The hope for humans is thst we develop means to both halt aging, and repair accumulated damage.
My best guess would be that they are so because they are eusocial.
As I posted in a comment below somewhere, I think it is the complexity of the nervous system that drives a tradeoff with repairable bodies. A brain does not want to have to retrain itself, but the history it stores makes it entropically very energy intensive to maintain. I think this drives most of what we see here: things without complex nervous systems (pyramidal neurons and such) have no disincentive in persisting indefinitely, because their relatively simple nervous system does not take increasing amounts of energy to maintain, and thus they can budget their energy for growing and other evolutionary benefits.
Most mammals have to budget their energy such that they can maintain the state of their brain, and thus have a disincentive for eternal aging: we either need to start forgetting earlier memories, which could potentially be bad, or we have to start paying the energy price of maintaining a very complex system. Energy usage tends to get optimized by evolution, so then, we end up trading off longevity.
Mole rats, however, being eusocial, have a different evolutionary strategy than most mammals. Since the entire colony effectively behaves as a single metaorganism, losing its experienced members is particularly painful if they have valuable institutional memory. Thus, there is stronger evolutionary pressure to pay the cost of maintaining these systems.
(I realize that isn't really what you were commenting about, but it does give a thermodynamic reason for their longevity, but not one simply based on temperature.)
> Thus, there is stronger evolutionary pressure to pay the cost of maintaining these systems.
... which implies that it is biologically possible to maintain them, which implies in turn that aging is a biological trade-off and not a physical inevitability.
Yes, I agree. I guess the question is what is meant by inevitable. The meanings of biological and physical in this instance aren't really all that different, if the biological problem is a limitation of the underlying physics. Ultimately, the scarcity of usable energy is driving this trade-off, which is a physical limitation of the universe. It becomes 'possible' in the sense that a O(n^100) algorithm is 'feasible' (see Arora and Barak, section 1.6.2). If maintaining a youthful state indefinitely increases our energy consumption hundredfold entirely due to the cost of maintaining a low entropy state in a highly complex system, is that really 'possible'? If we have to pay an ever increasing energetic cost to maintain ourselves, it is both a biological trade-off and a physical inevitability.
This raises an interesting point. Having said that losing experienced members is particularly painful, I am now thinking about how someone's feeling of meaning in life affects lifespan. Could it perhaps be the case that there is a self regulation mechanism in which perceived usefulness drives the brain/body to try and stay operational longer?
Interesting...that's different, and does not square with the article's premise. It does not sound like that organism is just getting longer life by keeping its cells in the refrigerator. Especially this part:
"Naked mole rats also appear to remain spry and healthy even in the final years of their long lives"
Sounds like they changed the shape of the curve, not merely stretching it out.
“Warm-blooded” doesn’t mean that the organism’s blood is literally warm. Warm-blooded means that the organism actively maintains its body temperature to facilitate a consistent rate of chemical reactions within their body. Cold-blooded organisms rely on external sources of heat; sometimes their body temperatures are lower than their warm-blooded counterparts, sometimes it’s much higher. E.g. crustaceans living in underwater hot springs.
Please note that nothing in the comment you're replying to assumes that every warm-blooded animal has a higher internal temperature than every cold-blooded animal.
The only assumption is that no warm-blooded animal is among those with the lowest internal temperature. The existence of some "cold-blooded" animals that are warmer does not change that.
You may be trying to save face, but if you did know that then your initial comment wouldn’t make sense. An organism who is cold blooded has to expose themselves to heat sources and thus take on more heat damage than a warm-blooded animal.
https://en.wikipedia.org/wiki/Negligible_senescence
That strongly points toward a biological reason for aging. I mean, sure, the heat death of the universe is inevitable, but that is not even remotely on the same time scale as the life span of complex organisms.