For instance, the statement:
> it's "an invention".
> As in natural selection decided at one point to introduce death. It really is the case that older lifeforms don't die. All mammals do though.
Natural selection is not an entity. It can not "decide" on anything.
What is here implied is that aging is an outcome of natural selection. Well, aging happens for many reasons, and it depends on how one defines aging (see Tom Kirkwood pointing this out decades ago); the implication meant here is that there has not been an optimisation towards perfection on the cellular (or organismal) level.
So, if damage occurs, the ideal situation would be that 100% of it is repaired. This does not happen. In theory it should be possible, but in actual practice, one will never have 100% repair, both on the DNA as well as protein/cellular level. Mutations will arise - that's for certain. There is no 100% perfect repair system. One can see this today with CRISPR-Cas9 promised as gene therapy tool, but whenever people ask about off-target damage and imperfect repair, those researchers dodge the question completely.
> if you study it, it becomes pretty obvious that in most cases reproduction and death are linked. Death is fundamentally a way to optimize reproduction, to control DNA variability and number of offspring.
I can not agree with this either. There are no specific death genes aimed at reducing life span per se (caspases/apoptosis has many functions, including formation of structure or killing virus-infected cells, among more functions). The main reason why reproduction is favoured, is because this is an evolutionarily stronger strategy, for most organisms. So more energy invested into offspring is more stable from an evolutionary point of view.
> The cells humans are made of are immortal, in the sense that human cells are capable of living and even reproducing indefinitely, if so directed by DNA.
Ultimately all cells are. Otherwise life would not be billion years old. The issue is not about immortality but damage and repair.
For instance, resetting telomeres in humans still would not make humans live thousand of years.
> Unfortunately this does mean that death is built into our cells and a lot of processes depend on aging and death.
No, it is not. What should that be? Describe that mysterious word "death". Which genes are related here?
In theory repair or restoration is possible; it is a finite problem. The question is how long it will take to improve on gene therapy on the nanoscale level. For instance, it should be trivial to enhance CRISPR-Cas9 to eliminate off-target effects; and enforce repair only happens in a guaranteed way. But achieving 100% is very hard - biology is nowhere near as strict as physics. Many genes are transcribed in a leaky manner; that has been one problem in biotechnology and synthetic biology as well. You can see this when you ask the Biobricks guys "which synthetic elements give us 100% control over genetic system xyz". Good luck getting them to commit to giving a single example here.
> At that point medicine will have to radically change and every tiny trace of every minor infection will have to be treated as a life threatening condition.
That's also not logical. If repair or genetic change is 100% or close to 100% accurate, why would ANY "infection" matter? In other words: why would infections be immune from genetic change? ALL viruses/bacteria use DNA or RNA. They are not exempt from ANY change here.
How so? Snakes only live like 30 years. Tortoises are long lived, but it is low hundreds years, not thousands.
spwa4•54m ago
If you study it, it becomes pretty obvious that in most cases reproduction and death are linked. Death is fundamentally a way to optimize reproduction, to control DNA variability and number of offspring.
Also, it is obvious that death has "levels". The cells humans are made of are immortal, in the sense that human cells are capable of living and even reproducing indefinitely, if so directed by DNA. Gametes are meant to survive your death, becoming your children. Now very few cells actually do survive, but that's a constant across pretty much every immortal species. On the other hand, every cell in your body was, in a very real sense, the first bacteria, the first cell ever, billions of years ago. So it certainly is NOT the case that all human cells age, senescence, and die. Only the human as a whole ages, and it is something your cells conspire to do (or conspire not to do, in the case of ovi (~ children), or in the case of cancer cells)
At one point, during the period mammals were all still fish, evolution was still experimenting with death, and so fish have much more variation in their aging and death than mammals do. If you go back further, to reptiles, there's even less death. Most reptiles could be alive for thousands of years (even though the odds are wildly against that). Most reptiles die because of slowly advancing accumulated diseases over time (meaning over hundreds of years, a great many diseases, parasites, even physical damage, ... accumulates. No one cause is really causing their death, but combined they introduce such a strain on the organism as a whole it "dies of old age". Except it's not really of old age in the sense like humans age, it's dying of what you might call 99.9% victories against disease. Eventually the 0.1% damage per incident overpowers the metabolism)
Unfortunately this does mean that death is built into our cells and a lot of processes depend on aging and death. Therefore we are very far away from curing death: you don't just have to fix the mechanism that "ages" our cells, but you have to find alternate ways of working for everything that depends on it. Resetting the clock may be easier, but even the methods that we currently know (ie. regrowing telomeres) have a bad reputation for causing aggressive cancers, and therefore shortening life rather than prolonging it. Plus, at best if you fix aging in humans entirely, we'll be like reptiles. At that point medicine will have to radically change and every tiny trace of every minor infection will have to be treated as a life threatening condition.
tosti•37m ago
blendergeek•27m ago
Are naked molerats the one weird exception with mammals?
tornikeo•24m ago
And here's to hoping that the exponentially growing technological capabilities will allow curing death in our (short) lifespans. By God we need that to counteract the ageing population.
plastic-enjoyer•24m ago
But is this life? I'm wondering if an immortal life can be a well-lived life
KellyCriterion•20m ago
Was there any progress at all so far?
themafia•10m ago
You could equally argue that it's a way to optimize lifetime energy efficiency.
> The cells humans are made of are immortal,
Yes but DNA transcription is not error free and most body parts do not grow back after being lost, most perniciously, our teeth. Elephants grow 6 sets of them, but due to their diet, they can end up fully losing all their teeth before they die.
> it's dying of what you might call 99.9% victories against disease
The planet we live on is warmed by the Sun. The Sun's energy can also destroy our cells. It's not just disease.