Is death a product of evolution

I wasn't refuting your position, I was advising caution with your terms, and then I expanded on your point. Indeed - the answer to the puzzle is two fold. If the population is at its maximum size then most animals are not dying of old age. Any genes that give a longer life span would not easily get selected.If the population is not at its maximum size though, and could support more members, where plenty of members are dying of old age, we still don't see this general trend and that is explained through the pleitropy paper referenced earlier. Genes that increase fitness early on are under more selective pressure than those that occur later on because there is more chance the organism will be eaten before getting the benefits.And that, as we say, basically covers the evolutionary reasons for old age.

Idunno... I still see aging as a motivation for evolutionary processes rather than a result... but then that's just contradicting what I said before...

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Nature ran a review article on the subject in 2000, available for free online. It does not talk specifically about death but more about theories of ageing. Among other things, the article talks about the disposable soma theory, "which is based on optimal allocation of metabolic resources between somatic maintenance and reproduction". I.e. An organism allocates resources to either (1) stay young or (2) reproduce (and what's in between, obviously). At least for C. elegans, longevity is in part controlled through a single metabolic pathway under the control of the DAF-2/DAF-16 transcriptional regulators (link). The article also mentions that for D. melanogaster, longevity is correlated with less fecundity.Well worth a read.

great, another paper to read ... Just to pick a point: (see article for graphic)You could also call the two curves "potential" vs "realised" as opposed to "protected" vs "wild" - certainly we as humans are reaching a level above "protected" to include "repaired" and "treated" eh?There is another thing to consider, and that is the relationship between longevity and overall population turn-over. The longer lived individual organism are (that participate in the reproductive process) the slower the population turns over to alleles of new organisms, and thus the longer it takes for mutations and selection to work their way through the population in the absence of severe survival selection events.Having a generation length of 20 to 25 years for hominids with substantial removal of adults from the population older than 30 to 40 years could have been critical in having enough genetic variation available - every 20 to 25 years? - to meet the needs of long term climate and ecological changes as selection operated on the populations.In other words, longer lived populations could be selected against because they wouldn't adapt fast enough to long term changes.We see mechanisms in unicellular life that can affect the rate of mutation to increase it during times of stress.It could be that the length of life of sexual organisms is also a reflection of the base rate of mutation needed in a population over a long term natural selection cycle.Just some thoughts.Enjoy.

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RebelAAmericanOZen[Deist
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It is interesting to note that death is perceived as a 'natural law', that all living things must die. This is actually incorrect. Most people think of animals and plants when they think of 'life', but there is so much more than that.Micro-organisms are known for their longevity. Given enough resources, bacteria can grow forever, but it is hard to determine an 'individual' bacterium lives on forever. That's easier to spot with multicellular organisms, such as slime molds and fungi.Fungi, for example, are modular organisms. That basically means you can split an individual in two, and both will grow on. The opposite are unitary organisms, such as vertebrates. If you give a fungus enough resources, it will grow on and on. Most fungi are in fact immortal. Only external factors (lack of resources, disease, etc) can cause a fungus to die.Some fungi are mortal however. They usually live in an environment that is not very sustainable and exists only for a short period of time (dung, for example). When grown in lab conditions with enough resources and such, growth will stop after a few weeks. Podospora anserina is one such fungus.But even here, mortality is not a certain destiny. Some mutants have a longer lifespan, months instead of weeks, and some have grown for more than 15 years and are still alive and well. So it seems that 'all living things must die' is not true at all. (interesting note: most of these mutations come with a side effect, like lowered or no fertility)But why is death (or rather aging) so common? I have no exact answer, although some ideas have already mentioned in this thread. Very likely death is an effect of having a limited lifespan by external factors (an almost certainty in nature), and may be a pleiotropic effect. I think it is a price we have to pay for the way our bodies are built, but I think it is a price worth paying.For more information on aging, this site is a nice, though not perfect overview.

welcome to the fray GVGS58, interesting. But what is growing on is not the same molecules chemicals that were living before - there is constant replacement, renewal, in the process of living.Are you connected with the linked website?just curious.

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RebelAAmericanOZen[Deist
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No, but that's life. A constant intake of chemicals and energy to sustain itself. That process can be neverending, but in such a state it probably has limitations on complexity and such. Not at all. Currently I'm doing a master thesis on the role of Reactive Oxygen Species (ROS) in aging, and during the research I came across this site. I found it to be a broad, informative site that is quite accessable to laypeople. If you want more details, I'd recommend reading the scientific literature (lots of references in that site, but I can give you some if you want).

Let us consider the chemical process we associate with life. It is a process that evolved according to the theory of evo. This process requires energy input to sustain itself.
Are you suggesting that available resources shape the life span of a species or dna strand in the case of our base beginnings?
How is it that predation did not evolve solely as the means of balancing the equation? How did the ending of a process become an integral part of a process evo dictates fights so hard to maintain itself? How does "survival of the fittest" require death?" The ability to outdo the competition makes sense. The ablity to die does not. I am inclined to think that death is a more fundamental "law" than an evolved part of the process.
I think it behooves us to look at the life spans of individual species. How is it the chemical process of each species has a limit to it's ability to maintain itself? I find this interesting.

The above examples give me food for thought. In the beginning the life process must have been imortal barring lack of physical limitations.
Death does not make a process continue or give one process an advantage over another. I am leaning towards evolution not having a role in it.

Th e fungi is a great example. Maybe the problem isn't with death, but with life. For modular organisms like fungi, it is hard to define an individual, and even harder to define the lifespan of an individual. When you cut a fungi into two parts, does the original fungal lifespan end and do two more individuals with new lifespans prop up? Or do whe consider the two fungi to be one organism living out the same lifespan?To get back to the topic, perhaps it is useful to think about why unitary organisms die. Let me propose that being unitary gives structural advantages due to its determinate growth, but a natural consequency of this is death. Death isn't directly evolutionarily advantageous, but it is a consequence of the vertebrate body plan and determinate growth which in turn has selective advantages.So that this isn't completely hot air, here is a review article that claims determinate growth is common in vertebrates, and can have selective advantages in some situations. [Just a moment...]
Unfortunately you need a subscription to access the article, it is rather old.

Not just fungi. There are animal that survives being split into several parts. The starfish, for example. Earthworm is another example i can think of. You cut these creatures up and they grow into more creatures.

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You have a good thought here. This might explain the variation. I am still qustioning How death became a factor in the first place. Why not predation? The typical boom and bust cycle in nature. I am thinking of us as the chemical reaction we are. All other chemical reactions we know will go on until the energy supply is used up. A star...a fire....ice melt on the sidewalk. This chemical reaction is different in that it will seek out ways to sustain itself.
Therfore it should continue on as long as it can supply itself or until it sustains irreparable physical damage. Now if one changes ones perspective....no individuals...the chemical reaction is the species as a whole or, the entire biomass. In either case the reaction continues through recycling. In this sense it can be indefinately self sustaining excluding outside intervention. Edited by 2ice_baked_taters, : No reason given.

Perhaps the question is in why we\organisms stop growing, why we\organisms change from using chemical reactions to {make more us} to using chemical reactions to {make more organisms} - procreate, make new packets of living cell matter from mixing disposable parts of the us\organism with those of another\organism.

Yes. The life cycle must tell a tale. Although the disposable perception is imposed. The parts "are". Thier nature in that venue is unknowable scientifically.
I am exploring how the life span limit we identify with "natural" death equates. Is it dictated by a physical law? Is it a product of evolution? Is it part of evolution? All things evolve. All things come to pass. Perhaps evolution is part of a larger process that includes death. Why lifespans are what they are.
Selection for survival....but slection for death? Again...how death and not predation? Even if predation still had not occured organisms would have died en mass as the food source dwindled...scavanging came first. I am currious...in terms of basic DNA/RNA how might the buildong block supply/scavanging/predation thing apply? Might "death have been a factor then or did it even apply? Does DNA/RNA have a "lifespan"? Where/how did lifespan/death enter the picture?

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Does DNA/RNA have a "lifespan"?

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Anything has a lifespan. Unless there is some input of energy to maintain an equilibrium (e.g. maintain the integrity of DNA) things will tend towards disorder (according to the second law of theromdynamics). I guess you could say that death will result when there is not enough input of energy to maintain the integrity of the metabolic functions in an organism. This could happen when, for instance, not enough food is available or when energy is used to produce offspring instead (See my message #18 for link to an article that talks about the disposable some theory).(The following piece will only deal with multucellular organisms)
You asked earlier in message #23 "How does "survival of the fittest" require death?". It doesn't. You can always think of it this way: While "the purpose of a multicellular organism might seem to be to make more multicellular organisms", instead think of it as "the role of gametes (i.e. egg and sperm) is to make more gametes through the vehicle of a multicellular organism". In this sense, multicellular organisms are just as immortal as prokaryotes are (although even they seem to age to an extent).