A qestion on evolution and the "first organisms".

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geistkiesel

Valued Senior Member
I am of the understanding that in the general topic of genetic evolution that all present organisms can trace their ancestry back to a single "most basic organism", Using the 'tree structure: as per Darwilnetc, I can see the logic in this.

Please tell me why a parallel "muttiple first organism" system would not work. What I mean is instead of a single organism evolving over time into all the complexity we see today in organic life forms we assume all life forms originated from a unigue first organsm, unique to one species that is. What is the error in assuming many first organsims all similar but different. Monkeys are different from humans not because of branching a few million years ago with the differences in organism being merely a record of the evolutionary dynamics of different but similar organisms. These unique orhaisms started from the get go at t = 0 with a lightning strike or oher workable stimulus.. If I remember some monkeys and humans differ in cytochrome C (sic) by one amino acid? Theoretically, monkeys and humans could have started very similar to each such that the evolved differences have not erased the similarities.

This model to me seem statistically more probable a sucessfull survival system compared to the "first organsism", a single entity that requires the maintenance of a strictly limited spectrum of a number of external or environmental parameters, temperature, pressure, ph, proper presence and mix of building blocks to assure statitisical completion of stable organisms. All of this requires the next, or some next generation of evolved organsim to be superior regarding survival attributes than the previous for the new line to ultimately domination of the "weaker" unevolved entities by the advanced sentities if I am not mistaken. Further, I would think it would be difficult to distinguish between the single organism model and the multple organism model.

So what is wrong with a "parallel" begining of huge numbers and varieties of starting blocks organisms simmering in the 'etherial stew' and where only "the fittest survive"?

Geistkiesel
 
Evolution could indeed have started in several places at once, but the parallel paths would not continue up to the level of higher animals, since the genetic mechanisms in multicellular creatures are so similar. Between monkeys and humans, the genetic structure is almost identical. The "tree of life", if you zoom into a particular branch, is made up of parallel but most importantly, interlacing paths. The first nucleated cells probably started in a symbiotic relationship between two different types of creature, the nucleus being a former bacteria. They way they know this is by comparing DNA. I have heard that the first organisms used something other than DNA, and there might have been several different chemical strategies, but one of them eventually won out over the rest.
 
I often argue that the differences between viruses and cellular life (archebacteria up to mammals) suggest that viruses as a life form did not evolve from the same base as us, but formed seperatly from non-living matter.

Much of the basic building blocks of viruses can exist in a non-organic state outside of the virus proper; protein shealths can form by themselves, RNA can self-replicate in solution, etc. Forming all the parts into a simple proto-virus would is realitivly plausable; at which point, evolution can bring about more advanced visus sepcies over time.

Prions may fall into this catagory as well.


But as spidergoat said, most of the living things that we see around us are SO similar structurally and genetically, that it seems more likely that we are all related to a common ancestor. DNA strands, millions of nucleotides long, forming in nature is rare enough - having it happen more than once, and in nearly the same order every time, would be so close to impossible that it pretty much should be considered impossible.
 
geistkiesel said:
Please tell me why a parallel "muttiple first organism" system would not work.
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No reason. In fact, many people think that there was likely many parallel instances of abiogenesis. I was going to try and answer myself, but I think ‘Genomes 2’ 2nd Ed. by T. A. Brown (BIOS Scientific Publishers Ltd, 2002) says it better than I could......

<font size=2>How unique is life?

If the experimental simulations and computer models are correct then it is likely that the initial stages in biochemical evolution occurred many times in parallel in the oceans or atmosphere of the early Earth. It is therefore quite possible that 'life' arose on more than one occasion, even though all present-day organisms appear to derive from a single origin. This single origin is indicated by the remarkable similarity between the basic molecular biological and biochemical mechanisms in bacterial, archaeal and eukaryotic cells. To take just one example, there is no obvious biological or chemical reason why any particular triplet of nucleotides should code for any particular amino acid, but the genetic code, although not universal, is virtually the same in all organisms that have been studied. If these organisms derived from more than one origin then we would anticipate two or more very different codes.

If multiple origins are possible, but modern life is derived from just one, then at what stage did this particular biochemical system begin to predominate? The question cannot be answered precisely, but the most likely scenario is that the predominant system was the first to develop the means to synthesize protein enzymes and therefore probably also the first to adopt a DNA genome. The greater catalytic potential and more accurate replication conferred by protein enzymes and DNA genomes would have given these cells a significant advantage compared with those still containing RNA protogenomes. The DNA-RNA-protein cells would have multiplied more rapidly, enabling them to out-compete the RNA cells for nutrients which, before long, would have included the RNA cells themselves.

Are life forms based on informational molecules other than DNA and RNA possible? Orgel (2000) has reviewed the possibility that RNA was preceded by some other informational molecule at the very earliest period of biochemical evolution and concluded that a pyranosyl version of RNA, in which the sugar takes on a slightly different structure, might be a better choice than normal RNA for an early protogenome because the base-paired molecules that it forms are more stable (Beier et al., 1999; Eschenmoser, 1999). The same is true of peptide nucleic acid (PNA), a polynucleotide analog in which the sugar-phosphate backbone is replaced by amide bonds ( Figure 15.5 ). PNAs have been synthesized in the test tube and have been shown to form base pairs with normal polynucleotides. However, there are no indications that either pyranosyl RNA or PNA were more likely than RNA to have evolved in the prebiotic soup.</font>
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This link may be of interest:
http://www.phschool.com/science/science_news/articles/rocky_start.html
What's more, these origin-of-life researchers suspect that the two major groups of bacteria, known as archaebacteria and eubacteria, originated on two separate occasions about 3.8 billion years ago. Only much later, the scientists propose, did these original microbes join forces to create the first eukaryotes, the group that includes plants and animals.
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river-wind said:
I often argue that the differences between viruses and cellular life (archebacteria up to mammals) suggest that viruses as a life form did not evolve from the same base as us, but formed seperatly from non-living matter.

Much of the basic building blocks of viruses can exist in a non-organic state outside of the virus proper; protein shealths can form by themselves, RNA can self-replicate in solution, etc. Forming all the parts into a simple proto-virus would is realitivly plausable; at which point, evolution can bring about more advanced visus sepcies over time.

Prions may fall into this catagory as well.


But as spidergoat said, most of the living things that we see around us are SO similar structurally and genetically, that it seems more likely that we are all related to a common ancestor. DNA strands, millions of nucleotides long, forming in nature is rare enough - having it happen more than once, and in nearly the same order every time, would be so close to impossible that it pretty much should be considered impossible.
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Good reply river-wind. I am sasuming that in either case, mutiple "first organisms" or only one, that large numbers of mateial making multi-million entity strands came later.

It seems to me that one organsim, the "first" and only, would need statistically rare environmental conditions, heat, pressure, light, ph, "food" sources and so on over a period of time in order to just survive, much less evolve. Likewise, it seems statistically probable that near identical organisms would form in the same "pool" such that monkeys and humans could have started out with differences and silimarities that are effectiviely, or functionally maintained intact throughout development.

Likewise, it seems to me that the variety of life we see from the depths of the ocean to the organsism afloat in the air that the parallel multi-first organism model would be more probable and would diminish the near zero probability that any such random model would develop into what we observe.

It is beyond my poor mathematical talents to construct a probability description that would answer the questions. Therefore I am left with an intuitive shrug of the shoulders.

Thnx,
Geistkiesel
 
Hypercane said:
Wasn't the "Eve" animal (first life form) a form of sponge?
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The first life forms were bacteria. The first animal life forms (ie. members of the Kingdom Animalia) were indeed sponge-like creatures.

<img src="http://www.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Animalia/animal-tree.jpg">
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geistkiesel said:
Please tell me why a parallel "muttiple first organism" system would not work.
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I dunno. Why shouldn't it work? Given that life started at least once, it might have started more that once under the same conditions.

However, if you're working on human beings and aps as being from different original organisms, that won't work. You're asking for too much convergent evolution.

One more thought. Once you have a single successful life form, then it makes it tough on other to develop the same way. The existing life would catabolize existing food supplies, including other life that was starting out. Other forms of life may just have not had a chance because of competition.
 
They've found strange creatures living deep underground and in the ocean depths, with metabolisms that are nothing like ours. Living off of sulfur, for example. I think they're having trouble bringing one up to the surface intact for study, so a DNA analysis, if indeed they have DNA, is pending. But I suspect this is likely to prove that life started from more than one original source.
 
Ok, as to the "multiple first organism," that is almost an inevitability. The likelihood is that RNA, using a clay surface as a solid bed, "evolved" the ability to reproduce. In whatever microenvironment in which this happenstance occurred, it is likely that it happened more than once, given the likely ubiquity of nucleic acids in this sort of environment. However, when life progressed to the cellular level (eg, encased by lipid membranes), it is likely that this only happened once, because this would give the replicators an extreme advantage (a controlled environment).

As to viruses, most signs point to their evolution from 'our' own DNA/RNA. They are unable to survive on their own, and would thus require living cellular hosts in order to reproduce. The fact that their genetic code is identical to their hosts' indicates that they evolved 'after the fact,' as parasites on their hosts' genome. Much of the available evidence indicates that viruses evolved from transposons, which can replicate themselves within hosts' genomes, to viruses, which can replicate themselves between hosts' genomes. The fact that some viruses' genomes are RNA is probably due to the fact that these viruses were in the transposon form of RNA when they managed to escape from the host cell. And if this sounds preposterous, think about the fact that a single-celled organism led to you typing on this keyboard now.
 
zyncod said:
Ok, as to the "multiple first organism," that is almost an inevitability. The likelihood is that RNA, using a clay surface as a solid bed, "evolved" the ability to reproduce. In whatever microenvironment in which this happenstance occurred, it is likely that it happened more than once, given the likely ubiquity of nucleic acids in this sort of environment. However, when life progressed to the cellular level (eg, encased by lipid membranes), it is likely that this only happened once, because this would give the replicators an extreme advantage (a controlled environment).

As to viruses, most signs point to their evolution from 'our' own DNA/RNA. They are unable to survive on their own, and would thus require living cellular hosts in order to reproduce. The fact that their genetic code is identical to their hosts' indicates that they evolved 'after the fact,' as parasites on their hosts' genome. Much of the available evidence indicates that viruses evolved from transposons, which can replicate themselves within hosts' genomes, to viruses, which can replicate themselves between hosts' genomes. The fact that some viruses' genomes are RNA is probably due to the fact that these viruses were in the transposon form of RNA when they managed to escape from the host cell. And if this sounds preposterous, think about the fact that a single-celled organism led to you typing on this keyboard now.
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I have no problem with my typing being possible from my ansestors being single celled organisms (even if assembled by some rational and consciously designed). I had always speculated my ansestors were single brain celled beings, as many being Republicans.

Ineresting post Zyncod.
Let's assume your virus theory is correct, i.e. created by the host cell wihin an organic entity. This would argue for a reasessment of virus based effects on organic systems, would it not? Further, viruses spread by contact would be relatively rare. One wouldn't expect the virus to be a constant in saliva, surface of the hands or skin in generakl), semen, tears or expended air from lungs. Did I leave anything out?

There is some claims in the literature (Stefan Lanka , I will dig out the reference, which isn't mainstream by the way.) that hepatitus (sic) is not a communicable disease, which has some merit if only from the recogntion that hep isn't spreading geometrically, neither is AIDS by the way. Further, hep can be isolated (within statistical liits) to recognizable social groups.


Geistkiesel
 
Actually, viruses are much older than people or even multicellular organisms. There are viruses that prey on bacteria - most people with a little bit more than basic knowledge of biology will be able to picture these bacteriophages as a jewel on top of a spider's body. So the fact that viruses can "shed" from every available part of our body is just evolution - viruses can't survive on their own so they need to be able to spread between hosts to survive. You're right that viruses are extremely unlikely to evolve spontaneously from multicellular hosts - we are just too complicated. But it is very likely that viruses have been evolving with us since we were bacteria. Actually, I would posit that viruses would be outraged at our slow level of evolution - HIV viruses can outevolve all of our existing antivirals in a single host, while we are not changing at all.
As far as hepatitis being non-communicable, I would have to say that that is bull. Many diseases do not spread geometrically, and limiting a disease to certain social groups is why the term 'epidemiologist' exists. All communicable diseases are limited to certain social groups, whether they define themselves as one or not.
 
Oh - and I will agree that Republicans are exempt from the laws of evolution since so many of them are voting their own premature death.
 
zyncod said:
Actually, viruses are much older than people or even multicellular organisms. There are viruses that prey on bacteria - most people with a little bit more than basic knowledge of biology will be able to picture these bacteriophages as a jewel on top of a spider's body. So the fact that viruses can "shed" from every available part of our body is just evolution - viruses can't survive on their own so they need to be able to spread between hosts to survive. You're right that viruses are extremely unlikely to evolve spontaneously from multicellular hosts - we are just too complicated. But it is very likely that viruses have been evolving with us since we were bacteria. Actually, I would posit that viruses would be outraged at our slow level of evolution - HIV viruses can outevolve all of our existing antivirals in a single host, while we are not changing at all.
As far as hepatitis being non-communicable, I would have to say that that is bull. Many diseases do not spread geometrically, and limiting a disease to certain social groups is why the term 'epidemiologist' exists. All communicable diseases are limited to certain social groups, whether they define themselves as one or not.
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The limitaztionm of communicable disease to social groups does not apply as a result of bio-chemical-evolutionary law. The containment of communicable diseases to certain social strata is by isolation and separation, intended and consciously designed or not, as through containmen t of a social class through the forceful mechanism of resulting racism, for instance.

geistkiesel
 
geistkiesel said:
Please tell me why a parallel "muttiple first organism" system would not work.
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It would not work in the way you described for the reasons touched on by other posters. The complexity of eukaryotic cells is probably due to the incorporation into these cells of originally distinct organisms. I would cite mitochondria and chloroplasts as the most obvious examples. In other words a number of 'entities' arose on early Earth with the capability to metabolise and replicate (end consequently to evolve). Their emergence and existence were likely to a greater or lesser extent interdependent (the character of viruses springs to mind). The relationship moved from parasitic to symbyotic to total unity. But that was in another country And besides, the wench is dead.
 
geistkiesel said:
Avatar, I am not sure of your meaning here. Is this intended to disprove multiple first basic live organisms or the contrary, all life forms sprainging from one biological entity, not one of millions of identical entities. but just one entity period? Or is there another purpose for the post?
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The purpose is just what it is - information, you decide where and if that information fits in this topic. I have no stance because I don't have enough scientific knowledge in this area.
 
Ophiolite said:
It would not work in the way you described for the reasons touched on by other posters. The complexity of eukaryotic cells is probably due to the incorporation into these cells of originally distinct organisms. I would cite mitochondria and chloroplasts as the most obvious examples. In other words a number of 'entities' arose on early Earth with the capability to metabolise and replicate (end consequently to evolve). Their emergence and existence were likely to a greater or lesser extent interdependent (the character of viruses springs to mind). The relationship moved from parasitic to symbyotic to total unity. But that was in another country And besides, the wench is dead.
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If organsims are integrating cells from originally distinct organsims what is the nature of the ancestral line iof these "distinc " organsims?

There is no contradiction to any experimental results, or any observations, of conditions denying the systematic origin of original-multi-identical organisms as the most basic first organisms. There is no natural process that systematically target offspring that shared only identical multi-ancestors as distinguished from having the same single ancestor. Such a mechanism could not possibly have the selection ability to distinguish among identical members of a common pool.

There is no natural force mediating the fact that identical members of a common pool adopted different evolutionary paths that ultimately resulted in awide range of genetic differences between members of different species. The actual state of an evolved organism mave be subject to being filtered out but not because of any condition merely defined by the fact of the ancestral history alone.

Correct me if I err, but I woud need something in the line of scientific proof to give up the simplicity of common-pool-ancestor:

There need be an unambiguous argument that rejects the exisistence of stable species lines originating from a common-multi-identical-ancestral-pool, which is subject to evolutionary exclusion only by virtue of the common-multi-ancestor attribute the species excluded.

The model:
  1. Planet A organic matter found to have one eintity common ancestor.
  2. Planet B organic matter found to have multi-common-entity ansestors identical to the single entity ancestor in(1).

Prove: Planet A organic matter survives while Planet B organic matter does not survive.

geistkiesel
 
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