I could google this but I thought it would be more interesting to ask it here. I am also sure Cecil has covered it. Feel free to provide the link.
I was watcing Two Towers last night and when the Elves turned up to help the humans at helms-deep I got to wondering about their immortality. I remembered a documentary about this years ago which said that mortality is a ‘deliberate’ function of cells and that without this mechanism organisms would just continue to live forever, constantly replacing old cells with new.
So why must we have this mechanism for death? And can it ever be switched off?
I am really really bored as may be obvious.
And talks given by the author suggest a reason: Because we are only “hosts” for our immortal genes/DNA. It is only necessary for us to live long enough to reproduce and raise our children. So our lives evolve around this process. There is an evolutionary benefit to grandparenting, thus it became (and is still becoming) more prevalent.
But the part of us that lives forever in some form only needs us for a relatively short time.
It might be able to be switched off or at least prolonged at some point. One of the causes of aging is that cells are destined to become less stable and more prone to random genetic mutations over time. That is, DNA “wears out” over time. This seems to be built into the DNA because different species have very different rates of decline. Research is already underway but we do not know the implications.
Tolkien’s Elves can be killed in battle or ‘of grief’. (I don’t know if this means suicide or if they just collapse.) One would think that, after living for hundreds of years, the Elves would be less than enthusiastic about going to Helm’s Deep (or elsewhere in LOTR) to die, especially since they seem to die quite readily in battle. Maybe only somewhat depressed elves went to fight.
Immortality in fiction requires, I think, a certain amount of invoking the supernatural, because aging is only one factor in why living things can die. Aging itself has several causes. One is the deliberate mortality of cells, which have a built-in mechanism (called apoptosis) that causes them to die after a certain period of time. Apoptosis, which is triggered biochemically, is important because it allows old, damaged cells to be replaced by fresh ones. Cells need to die as often as new cells are made. If apoptosis fails and new cells are made without old ones dying, the result is cancer. Another cause of aging is the byproducts of ordinary metabolism. Many of the chemical reactions that go on in your cells have products that cause damage to other components of the cell. This is why the cells must eventually die and be replaced – otherwise, they eventually wouldn’t function properly, and this might also cause cancer. The last aspect of aging I will discuss is telomeres, long strands of ‘junk DNA’ at each end of a cell’s chromosomes. Telomeres may serve to protect the DNA against damage. Over time, the length of these strands of DNA gets shorter and shorter. There may be some connection between the length of telomeres and the longevity of an organism, but there has also been research that shows there’s less of a connection.
But, as I said, aging is only one aspect of mortality. For modern humans, preventing aging would probably allow most people to live for a very long time, if not practically forever, assuming that preventing aging would include preventing heart disease, stroke and cancer. True immortality would also require the subject to be immune to all infectious diseases (which could be done with a very powerful immune system, perhaps coupled with a radically different biochemistry) and to injury. The last – preventing death by physical injury – would be very difficult.
Preventing oxidation of cells is difficult. Minor help comes from consumption of antioxidents. There is some evidence that a healthy diet rich in antioxidents can protect cells enough to fend off some cancers.
But no one has been able to prevent oxidation.
The longer life spans due to medical improvements is actually coming at the expense of the young. The elderly (who are just hanging on to life without much quality), are a financial burden that it about to get out of control, and a burden on the system and families of the world.
For the sake of everyone’s quality of life, we might be best if everyone just keeled over and died at a reasonable age.
Don’t you think that it is a good thing that humans die? How much more miserable would things be if every human that was ever born was still alive? If we didn’t die, there would have to be draconian laws to limit people from having kids that would make China look liberal.
ChoosyChipsAndCeilingWhacks: I wouldn’t exactly say that genes are ‘immortal’. When a person has children, some of their genetic material will be passed down to their children. In humans, elements of each of the paired chromosomes are mixed to produce a full set of these chromosomes, none of which are exactly like the parent’s. (Also, one sex chromosome – one of the X chromosomes for females, and either the X or Y for males – is passed on.) Some genes which are active in the parent will not appear or will not be expressed in the children, and some of the genes expressed in the children would have existed but been inactive in the parents. This process (meiosis and sexual reproduction) results in an individual which is a member of the same species but has some fundamentally different characteristics. This is highly advantageous for evolution precisely because the parent’s genes are not immortal – it contributes to the genetic diversity of the species. Ultimately, coupled with mutation, the process can give rise to a new species. Personally, I think theories about ‘selfish’ or ‘immortal’ genes are great for getting people interested in molecular biology and genetics, but anthropomorphizing genes (and even making them more-than-human) misses one of the basic concepts in these sciences, the idea that living things are essentially chemical. (For the purposes of this forum, I should add that this does not necessarily imply anything about the spirituality of humans or other living things. Humans may be spiritual even if we know they are fundamentally chemical, though that is an issue outside the scope of science.)
Dude, you’re not gonna be counted as “really really bored” until you confess to watching Fellowship(ext) & Towers(ext) & Retun back to back with a 12-pack of Guinness & a couple pizzas for company (…and let me know when you plan on doing this & I’ll just nip on over to your island to supervise the proceedings).
You asked “Why must…” which implies a purpose to aging & dying. That implies some kind of Design & Manufature process which results in our existence. Why does anyone design something to fall apart after a determinable lifespan? The answer, my friend, is “Planned Obsolescense.”
You see, God could have taken longer than 6 days to create Everything, but he was facing a deadline for a VERY important client in just over 2 weeks. He had to produce something that would be a guaranteed hit (hence The Grand Canyon, the Fjords of Norway and The Isle of Man), but the corporate philosphy over at Omnipotent Creations demanded universal incompatability within 5,000 years. His Job was on the line. So he quickly pumped out “Eden” on the earth platform and, after a day’s rest and a few days of testing, delivered it to The Client ahead of schedule and under budget with free upgrades to complete development of the remainder of Everything as the client’s Needs and Preferences changed–Very clever I think. He ended up getting the high seat at The Counsil of Heaven for that project!
The Client was naturally very pleased with the entirety of the project, especially the long-lived bipeds which engaged in all sorts of entertaining behavior for up to a thousand years before expiring–which was alright because, like any product, they became predictable and their entertainment value waned over time. All was fine until The Client accidentaly spiled a pitcher of water on it–nearly destroying the whole thing. He managed to get it dried off and, fortunately, was able to get most of the life forms back up & running much as before. But since that accident it never functioned quite the same. The bipeds especially behaved radically differently and suffered from an out of control reproductive rate and comparatively brief lifespans. It was still entertaining enough, but it was no longer what the client wanted.
Seeking tech support from Omnipotent Creations turned out to be a dead end. The manufacturer pointed out that it had been a special project developed by a single diety. Sure, the details of the plan were still around but the diety in question had been promoted beyond reach–the project was no longer supported. The tech advisor offered to troubleshoot using God’s documentation, but only at an astronomical cost. In the end The Client moved earth to a little-used parlour in the South Wing where it ferments in disuse to this very day.
The combined effects of entropy and oxidative respiration, plus the lack of strong selective pressure to sacrifice metabolism for the sake of longevity as a means of propagating the species, all contribute to our finite life span.
We could, on average, all live a bit longer, but our abilities to self-renew must be balanced against the costs incurred by self-renewal (oxidative damage), and the automatic susceptibility to proliferative disorders combining the two gives us. It would appear, in most animals, and especially mammals, cells either senesce or eventually give rise to cancer; if we do not self-destruct at the celluar level, we will at the systemic level. Perfect fidelity in DNA replication halts evolution; imperfect replication leads inevitably to carcinogenesis and defective gametogenesis. The only evolutionarily sound compromise is loss of procreative ability prior to the accumulation of excessive genetic lesions. Until very recently, this meant almost certain death while in our reproductive years, as is true of most mammals. Our rapidly growing lifespan coincides with the birth of culture, but there are still biological checks that only the simplest asexually-reproducing organisms can circumvent and remain viable as species.
What is becoming of these boards?? Since when can someone waltz in here, intimate they haven’t memorized all The Master’s columns, and not get a big noogie?
The reason you can’t be immortal (yet) is because there’s no way for all the cells in your body to easily communicate very well. You cannot have cells that grow constantly-unconditionally because they would never know when to stop growing. So each cell carries a piece that is responsible for division, and each time a cell divides that part gets slightly damaged. After so-many-times, it stops working and the cell stops dividing. You need this to build a creature with a complicated physical structure, because the parts have to be sized properly to each other or else things don’t work.
This is not to say there could not be some method introduced to cause human cells to reproduce more, but the cells themselves would not be able to manage it automatically. And it won’t be occurring for a while.
I have read that the hydra protozoa is one creature that (as far as is known) as no technical age limit. It can fully-replace all the cells in its body–but it is a very small and simple creature, and this is the main reason this is possible. Can do quite a number of other surprising tricks too, we should be glad the planet is not overrun with the things.
…Oh wait-- … ummm …it is.
Oh well.
~