How did viruses originate?

[NPK]

How did viruses originate? Are they all assumed to have a common ancestor or did they spontaneously exist independently?

[Conceptual]

A virus is fairly simple and contains RNA or DNA and a protein coating. It is not alive but needs a host to propagate itself. It simple state would suggest their existance before any viable cells. As cells began to evolve, viruses may have played a role in the evolution of cells by helping to modify the DNA faster than random mutations. Somewhere along the way their role changed into being more detrimental. This may have been due to multicellular lifeforms having a better way to evolve the DNA.

[ecoli]

Conceptual is correct, except for the stating that viruses are not alive... this is still under debate.

 

I find it very interesting, as he has pointed out, that viruses may have played a large role in speeding up evolution. By injecting their own genetic material into it's hosts cells, viruses could have spread genetic material cross species. Who knows the full extend on this could be.

[rakuenso]

though viruses would only affect genetic material for eukaryotes if it injected its DNA into gametes (i don't know of any that do, at least not for humans, can anyone provide me with a few examples?)

[zyncod]

Actually, since all viruses require host cells in order to survive, it is doubtful that they predate cellular lifeforms. In fact, most scientists now think that viruses are an outgrowth of such "lifeforms" as transposons. Transposons already have the replication and/or transcription machinery to assure their survival. All they would need to acquire would be a protein coat.

[RyanJ]

Actually, since all viruses require host cells in order to survive, it is doubtful that they predate cellular lifeforms. In fact, most scientists now think that viruses are an outgrowth of such "lifeforms" as transposons. Transposons already have the replication and/or transcription machinery to assure their survival. All they would need to acquire would be a protein coat.

 

I agree with that - without host cells a virus is useless (they can't reproduce) though they are very primative but very good at what they do - they must have formed as early as the earliest cells I think. the reason they have not evolved to something more modern is they have never needed too - they are still very dangerous things.

 

As for weather a virus is alive - it could be eather and I agre this is still under debate. They can't reproduce on their own and my understanding of the definition for things lliving or not says that they are not technically alive....

 

Cheers,

 

Ryan Jones

[Mokele]

I'm with zyncod on this: being an obligate parasite, a virus cannot effectively exist without a host.

 

As cells began to evolve, viruses may have played a role in the evolution of cells by helping to modify the DNA faster than random mutations.

 

Then there would be no viruses, as doing what you describe would result in them all sacrificing their "lives" for others. Given that the virus gets nothing out of it, nor is there any reason to assume that viral intervention is necessary to sustain a vaible mutation rate, I find your idea highly implausible.

 

This may have been due to multicellular lifeforms having a better way to evolve the DNA.

 

Multicellular life evolves is much the same way as unicellular life. A Nobel Prizewinner once said "What is true for E.coli is true for the elephant".

 

Mokele

[EvoN1020v]

A virus is fairly simple and contains RNA or DNA and a protein coating. It is not alive but needs a host to propagate itself. It simple state would suggest their existance before any viable cells. As cells began to evolve, viruses may have played a role in the evolution of cells by helping to modify the DNA faster than random mutations. Somewhere along the way their role changed into being more detrimental. This may have been due to multicellular lifeforms having a better way to evolve the DNA.

 

Excellent explanation Conceptual. As you do point out that viruses have multicellular lifeforms and having a better way to evolve the DNA. In the other thread entitling "Evidence of Human Common Ancestry". I tried to explain that Darwin's theory could actually happen. Maybe Conceptual's explanation helped my hypothesis?

 

[Bluenoise]

Zynods right, it's believe that many viruses originated from self copying dna sequences like transposons. Like a LTR element with an env gene is pretty much a retrovirus.

[Mokele]

Maybe Conceptual's explanation helped my hypothesis?

 

Conceptual's explanation was very flawed and bears little resemblance to reality.

[Helix]

Viruses cannot predate cellular life; they are dependant on cellular life for survival. They may be an offshoot, as was said, or they could be an accident, or even a freestanding "species" (species is in quotes because it is still being debated whether or not they're living).

[RyanJ]

Viruses cannot predate cellular life; they are dependant on cellular life for survival. They may be an offshoot, as was said, or they could be an accident, or even a freestanding "species" (species is in quotes because it is still being debated whether or not they're living).

 

ea I agree with you 100%. They can't have evolved before that (Unless they could reproduce on their own or by infecting other viruses which would not make them a virus) because they could not have reproduced. But the simplicity of the virus also tells us that they must have evolved a long time ago and due to their effectiveness have never evolved.

Maybe they evolved after the first single cell organisms?

 

Cheers,

 

Ryan Jones

[EvoN1020v]

I never took biology class, so it was interesting to learn about viruses. So I assure that Darwin's theory is still a "theory".

 

[RyanJ]

I never took biology class' date=' so it was interesting to learn about viruses. So I assure that Darwin's theory is still a "theory".

 

[/quote']

 

Fact... How many times have I stated this? *Get out my notepad...* 5 times so far.

 

Fossil record does prove that there is a disting progression from ape to man and sill further back. It is fact. Lets also not forget the genetic code sequences - more proof. And of corse we have the fossils of other animals evolving over time too... makes for some pretty colclusive proof if you ask me.

 

Although I'd like to see some fossils of viruses... i know there are some of bacteria but viruses I've never heared of...

 

Cheers,

 

Ryan Jones

[zyncod]

But the simplicity of the virus also tells us that they must have evolved a long time ago and due to their effectiveness have never evolved.

 

It depends on what you mean by "evolved"; if you mean more complex, yes they have (compare vaccinia to bacteriophages). If you mean capable of division on their own, no they haven't. Viruses are perhaps one of the most highly evolved creatures on this planet due to the incredibly high selection pressures. They need to evolve so quickly, in fact, that they have upped their mutation rate (pretty unique among "organisms") - HIV's nucleic acid replication is 1,000,000x more error-prone than our own.

Another cool thing is that large stretches of the viral genome in simpler viruses are nested; it's equivalent to having a novel that you can read backward and forward (in terms of complexity).

[NPK]

Fossil record does prove that there is a disting progression from ape to man and sill further back.

 

Scientists don't believe man descended from apes. The current theory is that they branched off separately from a common ancestor.

[EvoN1020v]

What kind of common ancestor, HUH?

[AzurePhoenix]

Scientists don't believe man descended from apes. The current theory is that they branched off separately from a common ancestor.

That's a very common misconception, but it's probably not true. The current theory, supported by genetic and fossil evidence, suggests that we split off from a common ancestor with chimps, long after gorillas and orangutans had already split off. "We" were apes at one point, and one could argue that we still are.

[Mokele]

Technically it was an ape. Apes (excluding humans) are a paraphyletic group. The ancestor that gave rise to humans was located within the ape lineage (which had already diverged from monkeys), ergo was an ape, in the same way that birds are a type of dinosaur.

 

Mokele

[AzurePhoenix]

This diagram from wikipedia illustrates the taxonomic timeline. To clarify, Pongo would be orangutans, and Pan is chimpanzees. I think you'll be able to get which are gorillas and humans

[zyncod]

Hey, Mokele (off-topic, I know)

 

Can we make it a rule that you're not allowed to debate the merits of 'Darwinism' except in the Evolution or Pseudoscience forums, or unless you start a thread that specifically has to do with the forum category? It gets extremely annoying that every single biology thread that mentions the words 'evolution' or 'evolved' somehow seems to deteriorate into the exact same discussion.

[RyanJ]

Hey' date=' Mokele (off-topic, I know)

 

Can we make it a rule that you're not allowed to debate the merits of 'Darwinism' except in the Evolution or Pseudoscience forums, or unless you start a thread that specifically has to do with the forum category? It gets extremely annoying that every single biology thread that mentions the words 'evolution' or 'evolved' somehow seems to deteriorate into the exact same discussion.[/quote']

 

How could you do that when evolution is not persuadoscience - it is science fact. It belongs here in a biology forum and not there

 

Cheers,

 

Ryan Jones

[Mokele]

Can we make it a rule that you're not allowed to debate the merits of 'Darwinism' except in the Evolution or Pseudoscience forums, or unless you start a thread that specifically has to do with the forum category? It gets extremely annoying that every single biology thread that mentions the words 'evolution' or 'evolved' somehow seems to deteriorate into the exact same discussion.

 

Well, I do try to segregate creationist garbage to psuedoscience, and split it out of useful threads when I can. Sometimes it's not always possible to make a clean split, though, and splitting would seriously mess up a thread.

 

Mokele

[BioNerd]

I never took biology class, so it was interesting to learn about viruses. So I assure that Darwin's theory is still a "theory".

 

 

You have obviously never taken a biology class, otherwise you would have known that our "theories" are really in fact "laws" without the same jargon. I, and my current physics professor, would argue that evolution is just as scientifically justified as the law of gravitation. We just use different words to describe our principles.

[Goalfinder]

Viruses have been playing an evolutionary game like humans, I think they have beaten us to it with HIV. A virus that is so prolific that it can hide in our protective mechanism and generate thousands of variants, so to overwhelm anything we throw at it. To understand viruses lets have a look at life in general, there are two strong points here

1) Brought down to its basics everything is a chemical code whether living or non-living. The code has to be reproduced and proliferated so that species can survive. The more it spreads the better is its survival chances become.

2) The more parasitic one is (living off other species) the more dominant that species becomes and survives better.

 

The evolution of viruses is still hazy because there could have been no single origin source of viruses as organisms as they are of different sizeez and complexity. large DNA viruses like pox- and herpesviruses could be presumed to have "degenerated" from cellular organisms, as their enzymes share a sequence similarity with sequences from cells than with other viruses. They all probably share a common origin of the reverse transcription function. Hence instead of a single family tree it could have been more spread across bushes. It is believed that Viruses of all the major classes of organisms - animals, plants, fungi and bacteria / archaea - probably evolved with their hosts in the seas.

 

the complications in finding the source arises because these viruses can jump from host to host, for those in arthopods can be traced to virus families infecting insects and mammals. Those in birds have jumped to humans.

 

There are indepth explanation about viruses in movie format here Bird flu virus part 1 or bird flu virus part 2

check them out