Do all organisms have to die?

Question

I understand (a little) that there are biological clocks and reason that after a certain amount of time organisms die. I'm wondering if that is something inherent in our DNA or in biology/chemistry in general. EG, is it possible that there could be a complex organism that would not die and would just regenerate it's cells In Perpetuam? I'm specifically interested in mammals and even more specifically interested in humans. But, I would be interested in hearing about other organisms like bugs, fish, plant, algae, etc.

I'm not asking if this practical, do we know how to do this, etc.. I just want to know theoretically if living forever is biologically possible, as far as we know. If not, is there an estimated upper limit?

It's definitely not practical. Lets assume an organism had evolved past disease and aging. It would still eventually die because with infinite time, the odds of it eventually falling into a situation where it runs out of food, or gets eaten, or dies in an accident go to 100%. So even an immortal species would still need to reproduce. If birth rates remain normal, but death rates are much slower, the population would explode, leading to many problems with food supplies and space and environmental issues. — user137, Mar 10 '15 at 15:45
Given current world state (lifestyles, climates, environment, food and water resources) and health tech I'd suggest it's in the region of 130-140 years, not sure anyone has lived longer and with billions of people on the planet that's a pretty good sampling effort but then again I'm guessing no one has yet stumbled across the perfect combination of genes and lifestyle so maybe a little longer — rg255, Mar 10 '15 at 17:47
@user137 Might not be practical for the species, but evolution doesn't really care about species survival. — augurar, Mar 11 '15 at 04:34
Are you also interested in bacteria and fungi that reproduce clonally? The situation is a bit different compared to higher animals. — fileunderwater, Mar 11 '15 at 08:51
@fileunderwater - no - I'm interested in the possible immortality of a single organism. There may be similarities in how they deal with the Hayflick limit, but I'm not sure. — Yehosef, Mar 11 '15 at 10:20
@Yehosef "single organism" isn't that easy to define though. Do you consider aspen clones a single organism or not? They are considered as one of the oldest living organisms, and should be relevant to your question, even though they are in one sense a multicellular plant analog to bacterial clonal growth. — fileunderwater, Mar 11 '15 at 10:26
@fileunderwater - fair enough.. I'm more interested in animals, but it's interesting to see other examples like you mention. — Yehosef, Mar 11 '15 at 11:22
According to Agent Smith (The Matrix series): Everything that has a beginning has an end, Neo... — Canadian Luke, Mar 11 '15 at 17:21
@user137 This argument makes no sense. There is no reason why if an animal only died through accidents, its birth rate couldn't adapt to reflect this. All animals' birth rates are tuned in a feedback loop which reflects death rates at different life stages, whether by accident, disease or old age, fertility rates and the size of breeding populations, and the potential consequences of overpopulation. — , Mar 11 '15 at 20:54
@jwg assuming the organism developed immortality over a long time the birth rates would have time to adjust as well. But as human life spans have increased over the last century and infant mortality has been greatly reduced, birth rates tended to remain high for several years, leading to a large increase in the number of humans. This is relevant because there are some researchers who think they can develop immortality for humans. Which, if possible, would happen over a short time scale, and birth rates wouldn't adjust. — user137, Mar 11 '15 at 22:43
possible duplicate of http://biology.stackexchange.com/questions/8176/do-immortal-organisms-exist?rq=1 — Mithoron, Mar 13 '15 at 00:52
related http://biology.stackexchange.com/questions/7010/is-there-any-kind-of-immortality-in-plants?lq=1, http://biology.stackexchange.com/questions/6884/why-is-the-hydra-biologically-immortal — Mithoron, Mar 13 '15 at 00:53

score 20 · Accepted Answer · answered Mar 10 '15 at 15:07

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The immortal jellyfish can revert back to its immature polyp stage after reaching maturity, then mature again, over and over. You can read more on the wikipedia page, but this ability means it can potentially avoid senescence altogether.

answered Mar 10 '15 at 15:07

C_Z_

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It too will die when the sun becomes a red giant. – Joshua Mar 10 '15 at 22:46
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@Joshua Technically, it will be boiled. But I can say this with certainty that it will surely die when you will disintegrate it into atomic particles. :P – arnabanimesh Mar 11 '15 at 11:40
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@Joshua naturally, but it will fry, not senesce, and that's what the question is asking about ;) – C_Z_ Mar 11 '15 at 15:29
The cited wiki page cites one iffy reference, but the other is good, and available online: http://www.biolbull.org/content/190/3/302.full.pdf+html The authers of this article indeed claim that Turritopsis may be immortal (!!). Thanks for this great answer. – AliceD Mar 13 '15 at 00:31
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@Joshua It is considered Biologically immortal, meaning that it will not die as a result of cellular processes... That does not mean that an external agent can't kill it. – AMR Nov 28 '15 at 21:33
@Joshua Well, if someone took such Jellyfish into an aquarium in a spaceship and took it to another solar system, then it could go on living. But of course, any such activity would probably eventually fail. – Fiksdal May 04 '16 at 05:08
Won't most bacteria be biologically immortal as well? If food wasn't a limitation. – Aurelius Nov 12 '23 at 22:24

score 6 · Answer 2 · edited Nov 29 '15 at 03:19

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You have a very interesting question there!

In order to answer, however, we must examine the most widely accepted "reason" for why we age and eventually die. Most scientists agree that it is because of mass cell death. Normally you and I would be able to deal quite well with mass cell death (such as a very large injury), the problem comes in when we are older because we cannot replenish them because we have physically exhausted our own supply of something called stem cells.

Most cells in our bodies actually cannot divide, so they rely on these stem cells (which can divide into any cell; think of them as a wild card) to replenish whatever cells die.

Sounds perfect, right? Not quite, each of us only have a given number of stem cells in our body (even though stem cells can divide into more stem cells, they usually don't). So the reason we age and die is because we "run out", if you will, of these stem cells and our supply of cellular replenishment is slowly cut off.

Back to your question, is it possible to stop this? Well you've probably already come to this conclusion by now, but theoretically if you could somehow supply the body with a constant number of stem cells, theoretically, you could live forever (or at least a really long time). This is evident, as you are aware, in flatworms, who have stem cells constantly circulating their bodies and are practically immortal.

edited Nov 29 '15 at 03:19

mgkrebbs

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answered Mar 10 '15 at 16:32

CDB

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Why do you call "running out of stem cells" the reason we die? It can just as easily be a side effect. – Slava Mar 10 '15 at 16:37
Sorry? Side effect of what? – CDB Mar 10 '15 at 16:40
Death process.. – Slava Mar 10 '15 at 16:41
That's what I have found to be the reason for aging in the time that I have studied it. – CDB Mar 10 '15 at 16:41
Oh, I see. I'm only saying that it is one reason for death, not all. Death can be caused by many things. – CDB Mar 10 '15 at 16:42
I know we study a lot of things that are not proven yet. I can remember things from my first biology books that we can laugh about now. That's when I try to bring as much logic in the game as I can. The fact is, we are not born with a fixed amount of stem cells. They grow and multiply rapidly at young age. And then at some point, you can observe a change of direction, instead of increasing, the amount of stem cells starts to decrease. Something causes this. – Slava Mar 10 '15 at 16:53
And I do not profess to know the answer to that, thus why I said it was theoretical. Of all the studies I have done this would most likely be the most mysterious, we know that we stop producing the chemicals needed to stimulate stem cell division as we get older, but beyond that we really don't know. It almost appears to be programmed into us, as if on purpose. I don't know how much Yehosef is wondering about the reason for aging though, and I was just presenting an idea on how to stop it (with a bit of needed scientific background for him to understand the idea of course). – CDB Mar 10 '15 at 17:03
Running out of stem cells seems more like an answer to "how" than to "why". – Solomon Slow Mar 10 '15 at 20:56
His question was regarding how immortalization could occur, therefore only a "how" answer was required, therefore that's all I gave. – CDB Mar 10 '15 at 21:11
Interesting - I thought that most cells can divide, its just that https://en.wikipedia.org/wiki/Hayflick_limit that limits how often before the DNA becomes too damaged (see also https://en.wikipedia.org/wiki/Senescence). Meaning, it seems that the cells stop dividing after a while but new stem cells can take their place and make new cells. So if you can either stop the DNA damage via expression of telomerase (see lobster longevity) or by generating adult stem cells to regenerate cells that can no longer divide. Either of these might work. – Yehosef Mar 11 '15 at 23:31
With many cells that is the case, however the cells I was speaking of are generally those that don't divide, such as nerve cells, brain cells, heart (muscle) cells and blood cells and those cells that rarely divide, such as liver and kidney cells. I suppose that stem cells would replenish those cells that are nearing or have reached the Hayflick limit merely by slowly replacing them with cells that have fresh DNA. – CDB Mar 12 '15 at 00:38

Do all organisms have to die?

2 Answers2