I was reading the selfish Gene by Richard Dawkins and he talked about one of the theories of death. Someone speculated that genes that injure the organism (plant, animal, bacteria, etc) before reproduction are weeded out through natural selection but teh genes that injure the organism after reproduction are allowed to reproduce and survive for millions of years, over time these destructive ‘post reproduction’ genes built up in all living things and that is why we die.
I tried to look up if prokaryotes live forever, and it appears they do not. If this theory were true you would assume prokaryotes, which are as close to original life as you can get, would live forever in ambient surroundings. maybe, if the above theory is true then they have been corrupted too.
Are there any other good theories on why we die or why death is a part of life? What about what role reproduction plays in death as most/all organisms don’t start to die until post reproduction. Also, what about the fact that in ‘normal’ wild surroundings most organisms (humans at least) only live about 1/2-1/3 their potential lifespans, does this factor into why we die?
Because an organism is only built to survive long enough to reproduce. Beyond that, its just dumb luck. The minimum design needed to keep an organism alive for a few years is significantly less complex than one needed to keep one alive “forever”, so it hasn’t arisen.
Some bacterias can apparently live for thousands of years in their special dormant forms.
Of course, you should remember that ALL lifeforms around today have gone through just as much evolution from early life as any other. Evolution does not necessarily create “higher” lifeforms: how simple an organism is is no guide at all to how long it has been removed from what it first evolved from.
This debate is a very interesting one and I have been wondering about it for some time.
Why do you think that an organism - say, a human - would have to be more complex in order to survive significantly longer?
It seems to me that the design for humans already supports unlimited lifespan in principle. Individual cells are created, develop, and die. The organism as a whole maintains itself this way and preserves the continuity of the individual.
Except that in reality, there is this mysterious process called “aging”. Aging is not wear and tear; it is an evolved, controlled process for eventual self-destruction.
My own conclusion so far has been that this is just a quirk of evolution. Evolution is not a controlled procedure leading up to certain designs. It is just random chance working in a complex, dynamic, very interconnected environment with very complex interactions.
Aging has coincidentally arisen from evolution just by random chance. End user requirements are not a consideration when “designing” organisms through evolution.
Oh, and there are plenty of other evolutionary “quirks” on display in the currently running version of the natural world.
I would suspect it plays an important part. Since most organisms are going to die, not from old age but from various external causes (predators, droughts, wounds, diseases, etc…), benefiting from very long potential lifespans wouldn’t be a significant evolutionnary advantage. They wouldn’t reach this age anyway, in essentially all cases, so wouldn’t have much more offsprings that their cousins lacking this “long life” gene.
If avoiding the deteriorations coming with old age which eventually will result in death is ressource-consuming, which seems likely to me, this need for more ressources would probably be detrimental enough to cancel the small advantage of being able to reproduce in an old age quite never reached.
That’s a WAG, of course.
Do we need a “long life” gene to live long? I don’t think that’s necessarily so. What we need is get rid of the “self destruct” gene.
This is exactly the central question for me. Of course, aging seems intuitively “normal”, because that has been the natural situation so far.
But my interpretation of some recent scientific results (stuff I read e.g. in Scientific American) is that the situation might be more complicated than that. We have actually evolved self-destruct genes. Probably they had some evolutionary significance at some point. Maybe this was when we were bacteria… as I said, just a quirk of evolution, not something that concretely benefited our species. (Since all species die, many of the genes should be very old. Although maybe some of them indeed benefited humans at some point. Maybe as a side effect of something else.)
Aging is a complex question. I will try to find some cites over the next few days, if I have time.
That’s an assumption too. That death would be caused (or mainly caused) by such a “self-destrucion” gene. I’ve read references to them, but I’m under the impression that at this point it’s mostly hypothesis which are in the process of being investigated.
Intuitively , it seems to me that any complex system needs not only sustenance, but also maintenance and restoration. Hence that a system able to keep functionning for a near-infinite duration (barring external causes of destruction) would consumme more ressources. For instance, it should include some system to detect/correct rare kind of failures, unlikely to happen over the course of a short lifespan, but which would happen with a nearly 100% certainty over the course of a very long life. So, in an optimal system the “maintenance/correction” capacity would be “intended” to keep the organism alive and able to reproduce for a duration which would be roughly equivalent or a little longer than its average life expectancy before extarnal causes result in its death.
Of course, as I wrote, it’s “intuitively”. Being a complete layman, I couldn’t back my argument with facts or studies.
Well, if we managed to avoid predators, illness, accidents and such, we’d die of old age.
This is quite an interesting article which sites the main reasons for ageing as;
Caloric restriction - “scientists discovered that feeding rodents a near-starvation diet lengthened their lives by up to 40%. Late last year, human volunteers entered a clinical trial in the USA to try and establish whether people who burn fewer calories will age more slowly.”
Oxidative damage - “Releasing energy through aerobic respiration spawns reactive free radicals – oxidising and potentially ageing toxins – as inevitable by-products.”
Genetic basis of ageing - “It is perhaps an inevitable conclusion that inappropriate gene activity could be an underlying cause of ageing.”
And some research is going on into the effects of glucose on ageing.
Well, speaking on behalf of the human race, we don’t. At least so far. As a collection of cooperative cells we could be said to die out every few years, that is, every cell of us that was alive at one point in time, say back in July 1992 , would have died and been replaced by a new cell by April 2004.
Individual cells have meaning only in the context of the purpose of the human body. As well, individual human beings only have meaning within the context of the purpose of the human race, and as such our individual deaths are as meaningless as the two thousand skin scales you shed while reading this important message.
It is important to think through time and conceptulize all lifeforms as a single entity.
Then forget it quickly. We, of course, have our hands full operating as individuals.
To use a more concrete example, let’s assume that your average hunter-gatherer live till he’s 40 before being killed by a mammoth. And that cardio-vascular diseases resulting in death usually occur on average around 60. An efficient “arteries cleaning” process would necessarily consume some ressources, resulting in the hunter-gatherer needing more food hence being more likely to starve to death. And such processes would be necessary for essentially all organs and all possible kind of failures (say, correcting cataract, since you aren’t going to live long if you’re blind). I would suspect that this man would be more likely to die at young age from lack of ressources rather than out of pure luck survive all mammoth hunts until he’s 60 and still be able to reproduce and pass on his “improved” genes.
Thiniking about it, it seems to me that the question “why haven’t we longer lifespans?” is roughly equivalent to “why aren’t we way much stronger, since it would allow us to kill mammoths bare-handed?”. Probably simply because it would be sub-optimal (that’s assuming that evolution tends to result in not optimal enough individuals being wipped out the gene pool).
From a more general point of view, I would suspect that the various disruptions an organism would have to be able to handle to benefit from an unlimited lifespan would likely be close to unlimited in number too. So, the question “why isn’t any organism organized in such a way that it could handle all of these internal disruptions?” is probably similar to “why isn’t any organism organized in such a way that it could handle all possible external disruptions, like hungry lions, lack of food for an extended period, extremely cold weather and lightning?” I would tend to think : because in both cases, it wouldn’t be cost effective.
Creatures that live longer life spans would naturally reproduce less or have less offspring ?
Imagine 2 primitive human tribes. One potentialy can live hundreds of years... the other a regular 40 to 70 years. If both were sucessful avoiding accidental death... the long living tribe would be depleting resources extremely fast since their numbers hardly dwindle. The short lived ones would have mostly young adults. Guess which one might starve themselves out of food ?
In a way its better to have a higher change over rate and avoid the dangers of losing too high a number of members. Higher reproduction helps also quicker adaptation of new evolutionary advantages... since you will have more new generations.... genetic innovation if you will would be quicker on the long term.
Another issue is cultural and "scientific/tools" innovation. The long lived tribe will have 200-300 year old people sticking to the tried and tested of their time. Ideas that are 200 years old. Whilst the short lived ones would have in those 200 years gone through 6 new generations or more. Each generation contesting and experimenting. They wouldn't be stuck to the same old ideals. The comparison I like to make would be ... imagine an American who lived during the 1850's alive today ? He might still be a adamant defender of black slavery ! Yet he wouldn't even be 200 years old.
I have an interesting article about ethical dillemas of Immortality or Longevity if anyone wants a copy. ( ze@tba.com.br )
Agree. However, as I see it, we have all the resources. DNA repair. Immune system. New cells grow all the time. Injuries heal. It doesn’t seem to me that all these assets necessarily have to wear out. This system already seems to be capable of functioning for a near-infinite duration.
You’re right. It’s been said by many thinkers that we are already immortal. Our children pass on and build on our achievements.
This also reminds me of the idea of the Star Trek “Borg Collective”. Another way to achieve immortality.
Unfortunately I have decided that this is not good enough for me. Too much of an individualist. I wish they would find that self destruct gene already, and develop that immortality pill. Where do I get in line for prescriptions?
I think that you bring up an excellent point and I was thinking the exact same thing, if any creature on earth live indefinitely it would just create more competition for the resources available. Imagine how much harder it would be to keep your tribe of primative humans fed if there were 1000 of them instead of 20.
Finding 50 times the amount of food seems like a good reason for humans(and other creatures) to keep their numbers low.
I mentioned this in another thread... this famous Brazilian architect is 95 years old... and he said he admires Stalin ! I can understand a hard headed communist admiring Lenin or Trotski... but Stalin ?!? That was when I understood that death is necessary and overall good. Or we would be condemned to stagnation.
Disclaimer - everything I write here is imho and ymmv:
I’d think that complexity isn’t an issue, as cancer cells are immortal and pretty low on the complexity scale compared to humans. Other than that, turtles have got a longer life span than humans, while dogs have got a significantly shorter life span. So it’s probably tied to the metabolism.
Well, wear and tear is offset by self repair due to cells being created. However, with every division of a cell and the copying of the DNA, there’s the risk of a flawed copy - the risk that those cells turn into malignant cancer cells. And that’s why there is aging - if cells were allowed to reproduce indefinitely, the organism would eventually get cancer.
Agreed. Plus, with mortal beings, there’s always a new chance for “trying out a different evolutionary path”. Now that we’re here though, evolution works too slow for mankind to benefit from it. Mortality as a concept is outdated and will eventually be defeated by our intellect
