Did Evolution Play a Role in Our Inevitable Death?

[Blenton]

We all die eventually. Its a fact. However what is the mechanism for this? Is there an evolutionary aspect to it that was evolved early on in order to limit populations, or is it merely a chemical defect that has remained thus far or yet a unavoidable consequence of how our cells are made up?

 

[mgb_phys]

Sex.
If you simply split in half then both halves continue living and split again.

If you make little screaming copies of yourself then your genes don't have any interest in keeping you alive once there are more of themselves in the offspring.

 

[Borek]

Short living species can faster adapt to environement changes, thus in some situations they will be preferred over their long living neighbours occupying the same niche.

 

[Andy Resnick]

We all die eventually. Its a fact. However what is the mechanism for this? Is there an evolutionary aspect to it that was evolved early on in order to limit populations, or is it merely a chemical defect that has remained thus far or yet a unavoidable consequence of how our cells are made up?

Death is as old as entropy.

 

[Lok]

There is a small worm in the sea that is able to rejuvinate itself. Not sure how it is called though.

It can reproduce normally but at some stage it just transforms into a younger self ( if that makes any sense)

Death must have been evolved :D as the beings that started it all are still kicking ( algea). But Death cannot refer to single cell organisms as they just split. It is a multi cell thing that involved the death or destruction of the organism.

 

[Blenton]

Single cell organisms can live indefinitely?

 

[Lok]

They can die of many causes. But their lineage does not, and considering that they split with one cell being a mother and one a daughter ( big and small ) and both live happily then one might say they live forever.

 

[Brawndo]

http://en.wikipedia.org/wiki/Turritopsis_nutricula"

Turritopsis nutricula, is a jellyfish that can revert back to the polyp stage, instead of dieing after producing offspring. Apparently in lab tests it reverts back to the polyp stage 100% of the time. Turritopsis nutricula is a pretty interesting read.

 

[Lok]

Turritopsis nutricula, is a jellyfish that can revert back to the polyp stage, instead of dieing after producing offspring. Apparently in lab tests it reverts back to the polyp stage 100% of the time. Turritopsis nutricula is a pretty interesting read.

Yeah that is the one... did not remeber if it was a jellyfish or a worm, but jellyfish it is.

 

[Monique]

Death is not something that evolved, we are bombarded everyday by damaging factors such as radiation and free radicals. It's a wonder that we can resist it.

 

[Lok]

Death is not something that evolved, we are bombarded everyday by damaging factors such as radiation and free radicals. It's a wonder that we can resist it.

Death is a evolutionary must that involves a programed or necessary termination of a multicell colony or more evolved organism. The primitive colonies can split into single cell lifeforms but the colony itself is dead and with it the information it once stored ( e.g. shape and size ).

The single cell lifeforms that we see today are the direct descendents of the first ever lifeforms on this planet. They evolved through mutations and may not resemble ancient bacteria but still they are as much alive as then.

 

[Andy Resnick]

Hang on- Lok and Monique could be discussing different phenomena. Certainly, Moniques's "death due to decrepitude" is not evolved. But apoptosis (Lok's programmed cell death) is different, and could very well be.

 

[jackie Gillis]

An interesting study being widely done is on Telemerase an enzyme that keeps the telemeres of DNA from "unraveling" - one of the major causes of ageing. The single cell tetrahymena has telemerase in all of its DNA and never ages or "dies" from aging. Humans have it in the stomach lining and in cancers - a cause of concern for using this to stop ageing. One possible evolutionary cause of death - the lack of this enzyme in all our DNA? If interested you can find massive research by looking up any of these terms.

 

[Borek]

Telomerase.

 

[Moonbear]

Hang on- Lok and Monique could be discussing different phenomena. Certainly, Moniques's "death due to decrepitude" is not evolved. But apoptosis (Lok's programmed cell death) is different, and could very well be.

Okay, are we talking about death of the organism (no hereditary mechanism other than it has to happen after reproduction occurs, and likely no evolutionary mechanism since even the earliest organisms died, though there might be some argument that there has been evolution of lifespan, or the prevention of death until later in the organism's lifecycle), or cell death? Apoptosis is essential to development (without it, we'd all have webbed fingers and toes, for example), and certainly is heritable, and since defects in the process can affect an individual prior to reaching a reproductive age, and interfere with them reproducing, yes, it would have an evolutionary impact.

I suspect, however, that the OP is inquiring about death of the organism from the phrasing of the question.

 

[Lok]

An interesting study being widely done is on Telemerase an enzyme that keeps the telemeres of DNA from "unraveling" - one of the major causes of ageing. The single cell tetrahymena has telemerase in all of its DNA and never ages or "dies" from aging. Humans have it in the stomach lining and in cancers - a cause of concern for using this to stop ageing. One possible evolutionary cause of death - the lack of this enzyme in all our DNA? If interested you can find massive research by looking up any of these terms.

Telomerase reduction is a necesity as old cells after 60 or so divisions contain a huge amount of DNA copy errors or damaged DNA which can lead to cancer.

If you take the telomerase in your lifetime you will have younger cells that live longer but you also enable cells which have damaged DNA to rapidly evolve into cancer.

 

[Blenton]

Well the question was why do we die. As quoted by our favorite blue guy "A living body and a dead body have the same number of particles. Structurally there's no difference."

 

[mazinse]

sure there is structural difference, no composition difference though. Structurally, all of the proteins/ dna would start to degrade if not preserved well, cells would no longer maintain their structural either.

 

[harborsparrow]

I wonder. I've had a house plant for most of my entire life. It has been clipped, repotted, rerooted, fed, neglected, in cycles. It is still genetically the same plant.

 

[Biophreak]

Death is not an evolutionary adaptation. Evolution is a procession that requires death to occur. Without death there is no evolution, so it is strange to ask if death is an evolutionary adaption, when it is actually an evolutionary given.

 

[Mattara]

From what I understand, the gene centric argument for "death as a product of evolution" (or more precisely, why populations of organisms do not keep evolving additional mechanisms to protect them from the accumulation of errors in and damages to the DNA past the point where they are unable to produce or care for additional offspring) is that there may be no selection for it in the first place. It seems to me that this sort of thought experiment is used to illustrate the differences between "for the good of the organism" perspective and the economy of genes.

 

[leroyjenkens]

I think the evolutionary reason we die is because we don't need to live. After we have kids and they're old enough to take care of themselves, there's no evolutionary reason to keep us around.

Death is not an evolutionary adaptation. Evolution is a procession that requires death to occur. Without death there is no evolution, so it is strange to ask if death is an evolutionary adaption, when it is actually an evolutionary given.

Random mutations occur regardless if a species dies or not. If that random mutation begins to propagate through subsequent generations until all of the newest offspring are born with it, then that species evolved, whether it's an advantageous or detrimental evolution. The fact that the great, great, great, great grandparents are still alive is inconsequential.

 

[Borek]

IThe fact that the great, great, great, great grandparents are still alive is inconsequential.

I would not say so. They compete for the same food, they compete for the same partners for breeding, thus they slow evolution down.

I remember reading about some species of wild goat (or something closely related) that had a relatively short life span - and the reason for that was that they lived in relatively fast changing environement, so fast evolution and adaptation was a paramount for their survival.

Unfortunately, it was in Polish - and I don't remember where I have read about it; most likely in one of popular science magazines published here.

 

[leroyjenkens]

I would not say so. They compete for the same food, they compete for the same partners for breeding, thus they slow evolution down.

True, that would slow it down. Unless they were able to expand constantly with their constantly growing population so that they don't reach the food limit of their environment, thus making them compete for food instead of working together. Once their expansion reaches places where the environment isn't conducive to their survival, they'd start competing for food/mates or start dying.

 

[jerrywickey]

Death is not an evolutionary adaptation. Evolution is a procession that requires death to occur. Without death there is no evolution, so it is strange to ask if death is an evolutionary adaption, when it is actually an evolutionary given.

There seem to be a number of replies along this line.

Death by predation has nothing to do with apoptosis. Because organisms are eaten does not mean they formulate genetic instructions for programmed cell death.

The notion that death is somehow a ubiquitous and endemic part of life is unsupported. Far from death being necessary for evolutionary selective processes, it's easy to show with simple evolution simulations that the adaptation of advantageous characteristics by reproductive selection doesn't suffer at all in populations where individual organisms enjoy biological immortality. Less fit organisms are simply eaten. Even if their population is not reduced, the proportion of their population dwindles over time in comparison to the increasing rate of superior organism's population growth.

Long, reproductive life is a robust evolutionary advantage. Any species adapting a longer reproductive lifetime would quickly overtake the population of less fit species.

A lot of junk DNA might accrues, but so what? Amoebae have 300 billion nt in their genome. One hundred times larger than a human being. All that extra DNA doesn't slow them down. It is apparent that both reduction of genome size and death are merely an adaptation since neither large genomes nor biological immortality have any evolutionary disadvantage. Large genomes and biological immortality are the norm. They pose no evolutionary disadvantage and should be expected. The small genome size of many ancient microorganisms suggest that death and reduction of genome size must have granted some unknown advantage to have been conserved over generations.

The parallel information processing systems which the genetic machinery of all modern organisms have adapted eliminates all losses due to unnecessary gene expression so long as the proteins expressed are not themselves detrimental.

The only other alternative is that genes did not arise by natural processes.

Jerry

 

[Biophreak]

In an immortal population natural selection ceases and reproductive selection takes over, but even then, only to a small extent. Without death culling unfit genes from the gene pool adaptive mutations never have a chance to rise to dominance, eliminating the possibility of speciation since there is a continual flooding of the gene pool with the same alleles. In this situation genetic drift and reproductive advantages carry the burden of producing fit individuals...and frankly these two mechanisms together just aren't enough.

 

[Kracatoan]

If death was "evolved" as you put it, what happened to everything which was around before death was evolved?

 

[SeeFeelTime]

Everything comes to an end and through death is rebirth. Without destruction there can't be creation.

Celestial bodies don't even exist forever.

 

[Biophreak]

Death never evolved. death- whether by predation, sickness, etc- acts to select for fit individuals. Death, along with reproduction, heridity of alleles, and variation among alleles is what drives life to thrive amid a changing environment. Without death natural selection comes to a screeching halt.

Also, to what was before death: death is the cessation of life, therefore it makes little sense to ask what was before death. In a place without life there is nothing around to experience death.

 

[jerrywickey]

eksquuze spelling please. my spell chekcer is broken/

Perhaps some are applying some sort of meta-physical quality to death. "Death is a part of life." "Death is rebirth" sort of thing. That is for a philosphical discussion not biology.

A organisms that enjoys biological immortality gets eaten just as soon as one who does not.

An unfit organism will fall prey "literally" to more fit organisms. There is not "natural selection" and "reproductive selection." Natural selection selects for those organisms which reproduce.

An organisms which produces many copies gains dominance. Others get eaten. Some die because of apoptotic events with in their biology.

The question was became of organisms before death arose was misunderstood by biophreak. What Kracatoan asked was if creatures that were biologically immortal lived at one time, where are they now?

Eaten. For any organism the likelihood of falling prey to a lethal event other than apoptosis increases over time. Even if an organism continually renews its biology as all living cells do until telemare signals apoptosis, that organism still suffers increased likelihood of death with each passing day.

But think about it for a moment. Every microorganisms is millions of years old. Many billions.

The machormolecular machinery within a microorganism continually fails. Its genetic machinery is in a constant state of promotion, transcription and translation to replace each failing protein machine with a brand spanking new one all the time.

During mitosis, the machinery is split into and each daughter cell gets half. The parent cell doesn't die, but neither daughter cell is distinguishable as the parent. In a sense either one of them is the parent.

In this way microorganisms are biologically immortal. Their biology continually rebuilds and repairs with "factory" new equipment all the time. The cell never dies, but many get eaten or parish due to other exterior conditions.

None the less, for every living microorganism, one could follow back the path of that organism to the point at which it was a product of mitosis and if we call that organism the parent it could then be followed back to the previous mitosis and back again until that species first arose.

Bugs life forever. So does any cell, so long as it has not adapted apoptosis. Some cell types in the human body have not adapted apoptosis.

Jerry