Did death evolve?

by **AstusAleator** on Fri Mar 03, 2006 12:22 pm

my 2 cents. It's necessary for an organism to eventually die, to make room for it's progeny. It is also necessary for organisms to die, to drive evolution. An organism with unfit genes, that didn't die but persisted and kept reproducing, would weaken the gene pool. So...
Yes. death has evolved, just as methods of reproduction and survival have.

Someone at the beginning of this thread listed the requirements for successful evolution as:
1. survive to reproductive age
2. successfully reproduce
I would add to this
3. die.

Mortality has remained a constant throughout evolutionary time (though changing in frequency and cause). But now, with the development of technology, humans are beginning to challenge mortality, and thus evolution itself.

by **AstusAleator** on Tue Mar 07, 2006 5:31 am

Here's a thought I stumbled on in the evolution thread:

For cells to form multicellular organisms or colonies (plasmodial slime mold) there must be intracellular communication. Perhaps with the development of this communication came the differentiation between selfish, altruistic, mutual, and spiteful relationships. At this time, with the development of altruism, cells began being selected for deleterious traits such as programmed death.

by **damien james** on Tue Mar 07, 2006 6:43 am

If only we could uncover secret of pesky telomerase and control chromosome short over time.

by **Pepper** on Sat Apr 29, 2006 10:45 pm

It may help to understand death if we try and look at things without being too anthropcentric. We could also consider the genetic material as the true "unit of life".

The first proto-organisms or self-replicating molecules were probably quite fragile outwith their natural suurondings and at the mercy of the environment. To counteract this they would have developed some form of outer coating - be it a simple carbohydrate or protein coat - to shield themselves. Now, fast-forward a few billion years and we see that this outer protective coating has evolved into something far more complex - the cell. This "super-coat" not only protects the self-replicator, but also repairs it and provides it with everything it could ever want. These "super-coats" eventually form organisms - just an incredibly comlplex way of protecting the self-replicator.

Viewed in this light there is actually no such thing as death. All that is happening is that the self-replicating molecule (living in a vast super colony) is "shedding" its "coat". It "lives" on in a new body - our offspring are us.

What has messed things up is that some of these "super-colonies" have evolved self-awareness. In a sense we (mentally) are a but temporary thing existing piggy-back style within the "coat". When the old "coat" ceases to be able to create viable gametes and rear young (new "coats")successfully, it succumbs to the wear and tear of life and breaksdown. The genes live on in the next generation protected in a new body with a new mind.

This argument doesn't really explain why death has evolved, but rather suggests that death (from old age) is just an illusion created by our perspective.

Maybe a bit fanciful though ...

by **Zeneth Entorion** on Sun Apr 30, 2006 2:54 pm

It is VERY unlikely that death evolved. The longer you live (and are fertile), the more offspring you are capable of generating. Death by old age is most likely a byproduct; in any organism's natural environment it is extremely unlikely that it will survive long enough to die from old age. Therefore those organisms which survive are those which exchange longevity for a more active life- that is, they use all their energy for surviving other foes and winning mates instead of on repair mechanisms to stop aging. Everything in life is a tradeoff; the organism which uses its energy in the most efficient manner wins.

As for the "making room for offspring" argument, I'm afraid evolution doesn't work like that. It isn't some kind of omniprescient deity which sees the future and then alters the genome accordingly. If and when resources start to diminish due to overpopulation, organisms will simply die off because they have nothing to eat.

by **AstusAleator** on Thu May 04, 2006 12:30 am

Zeneth Entorion wrote:It is VERY unlikely that death evolved. The longer you live (and are fertile), the more offspring you are capable of generating. Death by old age is most likely a byproduct; in any organism's natural environment it is extremely unlikely that it will survive long enough to die from old age. Therefore those organisms which survive are those which exchange longevity for a more active life- that is, they use all their energy for surviving other foes and winning mates instead of on repair mechanisms to stop aging. Everything in life is a tradeoff; the organism which uses its energy in the most efficient manner wins.

As for the "making room for offspring" argument, I'm afraid evolution doesn't work like that. It isn't some kind of omniprescient deity which sees the future and then alters the genome accordingly. If and when resources start to diminish due to overpopulation, organisms will simply die off because they have nothing to eat.

Sorry for the huge block quote, but I wanted to have it right there so I could remember what I'm replying tol.
Zenoth - death and evolution are irreversibly linked. Without death there is no evolution. It is obvious that death affects evolution... so why shouldn't evolution affect death?

More to come... my girlfriend needs me

by **AstusAleator** on Thu May 04, 2006 5:12 am

Take the Damselfly for example. It's mature morph has no mouth or anus. It is programmed to simply find a mate, copulate, and die. If that's not an evolutionary trait then I don't know what is.
Furthermore, look up apoptosis. Programmed cell death.
Take Plasmodial slime molds for another example of adaptive death. They are individual single-celled organisms that are capable of functioning as a colony. When plasmodial slime molds form sporangiums, the cells that form the stem "sacrifice" themselves so that the cells that will produce spores can reproduce successfully.
Altruism is a recognized trait of kin selection. In a nut shell, it is one organism "sacrificing" it's fitness (ability to succeffully produce viable offspring) for the fitness of one of its kin, so that its kins genome is conserved.
So, my stance is that evolution DOES determine when and how some organisms will die (if they live long enough).

Zeneth your statement about the "making room for the next generation" argument is misinformed. You're right that there is no conscious entity that is making sure that the previous generation dies before they can outcompete the next generation. That doesn't mean that it doesn't happen though. In fact, it's an observable trend in just about every species. There is conflict between generations, but it is brief as previous generations usually die off (or stop reproducing) by the time the new generation reaches its prime maturity. If you don't understand the evolutionary mechanism behind that I can expound upon it.

Pepper: I find your comments to be very insightful and fascinating. I like to think of that myself, how "I" am just a consciousness in a body, and that the part that is "me" will only exist in this body. My genes will carry on, but "I" will not. What you said is a good reminder that evolutionary death is not the same as the anthropocentric concept of death that we have developed. Kudos.

Dave

by **Linn** on Sat Jun 03, 2006 2:09 pm

Well I actualy have not answered this Q yet

My answer is yes Death evolved.

Have a nice day!

by **LMJ** on Sun Jun 04, 2006 9:15 pm

This is an interesting topic. My initial thought was that death caused by ageing did not evolve, but was just an inevitability. If something is replicating itself over and over, it is bound to make more mistakes as it gets older, which means that there's more of a chance a fatal error will occur... But then I thought about the example that James wrote with the initial post, about the comparison between an "immortal" population, and a population with a given life span, but on a more genetic level.

I guess that if the immortal population keeps reproducing, the copying of the genetic information becomes less efficient over time and mutations build up in the population, making it weaker. The population where the individuals are programmed to die after a certain amount of time would do most of their reproducing in their "prime", so the copying of genetic material would be more accurate. So after the same amount of time has passed, the "immortal" population would be much weaker and not able to compete with the population with a set life span. So maybe dying of old age did evolve?

Sorry if I've repeated most of what's been said... it's a really good topic though!