Why aren't viruses considered to be "alive"?

You know, science has never been my strong point, but this is one thing that always bothered me.

I forget which characteristic of life viruses lack, but doesn't that speak more to the fact that our current definition of life is incorrect/flawed than anything else?

Does anyone else feel we would be a lot better off if we'd stop being so stubborn with this?

I always hear stuff like "This planet is too hot to support life" or "This planet doesn't have the proper atmosphere."

Well, yeah, if you're assuming earth life and any other life in the universe is identical. That is illogical, in my opinion.

Is anyone else irked by this?

It is a good question.

Most scientist consider virus not alive because it can not synthesis proteins and replicate on its own - only through host ( beside dormant state for very long period if host is not found).

On the other hand - our genome has a lot of retroviruses.

We should change the definition.

And yes - I think life can be methane or silica or whatever based somewhere else in universe. Why would water be the only solvent?

Viruses don't meet the scientific definition of life because they can't reproduce (or do anything else for that matter) without using a living host cell.

Well water's polarity and subsequent high surface tension makes it especially conductive to life. Land plants that require the use of xylem wouldn't be able to transport water upwards if the liquid didn't cohere. That's not to say that water is the only liquid with this quality, I'm no chemist.

Cells are considered to be alive because they replicate proteins and maintain homeostasis. A virus is just some DNA or RNA sitting inside a protein capsule (some have membranes, like HIV).

OK, so just because they need a living host cell to do whatever, why does that mean they aren't alive?

The fact they can do whatever should say something.

If you give a rock a living host cell, the rock will not do anything.

Viruses clearly have some sort of life.

Well then, Cutwolf, is a prion alive?

[edit on 26-5-2007 by Johnmike]

You could probably consider a virus more like a corrupted function.

Originally posted by laiguana
You could probably consider a virus more like a corrupted function.

What?

Originally posted by Johnmike
Well, then Cutwolf, is a prion alive?

You're speaking gibberish to me, but if its anything like a virus, yes.

Because viruses are basically a bunch of RNA/DNA enclosed in a protein capsule. They are unable to reproduce on their own and have to hijack a cell to assemble copies of itself. It does not "eat", it does not form colonies, it does not communicate, it does not react to environmental changes,etc.

All it does, is drift until it meets a host cell where it replicates.

A prion is an infectious protein that affecys the brain and the nervous system. It's smaller than a virus and does not have any RNA/DNA.

No a piron is a protein crystal and nothing more.... Among the critira for something being alive is that is can maintain itself and self replicate. Virus' do neither.... if anything they are very simple parasites. They are considered to be right on the border of life.... now if you can find a virus that does one or the other or both (and I am sure that they are out there) then it has crossed the threshold.

One of the things I find interesting is that the largest single cell animal, a bacteria that lives in tidal pools in Nambia is the size of this period (.) and can be seen with the naked eye.

Based on our current definition of life, things need to do that.

My question is why we assume that our definition of life is 100% right?

I think, logically, its clear viruses are alive.

bacteria have the critereia necessary for the current model of life and can be good or bad or indifferent

not anything like a virus and apples and oranges in comparison.

but hard to say a parsite is not alive.
just because its dorment.
especially if it takes over living things.

so the definition of life is very limited to most peoples head space even to the extent of we are the only life in the universe, or its carbon based, or whatever set of rules we impose on the definition of life and consciousness for that matter.

I have a definition of Information that is not accepted by Byrd who has a degree in Information Technology I believe.


I also have a definition of consciousness and life and dimensions and antigravity that most dont live in or think about or understand

Cheers, great question.
the textbook answers do not make a correct reply
just the limits of the current model.





[edit on 26-5-2007 by junglelord]

Originally posted by Cutwolf
Based on our current definition of life, things need to do that.

My question is why we assume that our definition of life is 100% right?

I think, logically, its clear viruses are alive.

In that case a computer virus is also alive?

No a piron is a protein crystal and nothing more....

A prion is a protein. End of story. Nothing cristalline here.

[edit on 26-5-2007 by DarkSide]

Originally posted by Cutwolf

If you give a rock a living host cell, the rock will not do anything.

Viruses clearly have some sort of life.

You've got a point there.

I've also been baffled by this question. Logically thinking we cannot prove that viruses are not a lifeform. The definition of "life" wasn't made up by the creator of all lifeforms to be an exact definition.

I really do understand Cutwolf. What we're doing is dividing the whole world in two extremes - yes and no, black and white.. [It's really late here, and I'm too drowsy to remember the name of the philosophy I'm talking about;] Why can't a virus be somewhere in the middle, a beta-lifeform of something? We have to think beyond our logic on this one...

Virusses aren't concidered alive / living because they behave more or less like inanimate particles. Their whole 'life' is chance and not influenced by the virus itself in any way.

They 'float' around untill they get into a compatible living cell, rna or dna get's absorbed into the cell's nucleus and reproduced, the instructins in the new rna/dna also tells the cell to start producing protein capsules for the newly produced rna/dna strands. these combine untill the cell get's filled up and bursts releasing thousands of new virus particles.

It resembles a chemical reaction more then life.
The only animate object involved in a virus' cycle is the host cell. the virus is inanimate matter.

It doesn't have senses (unless you count relatively simple reactions caused by seperate chemicals in the capsule of the virus and the cell walls)

We're talking about a scale where counting the number of molecules would not result in an unrecognizable ridiculous large number

The cell membrane of a human red cell is only 2 molecules thick
(source: A. K. Solomon - Red Cell Membrane Structure and Ion Transport.)
Worth noting though red cells don't have a nucleus, are a lot smaller then other cells with nucleus. But it gives you an idea of scale as viruses are much smaller then cells.

Edit spelling.

[edit on 26/5/2007 by David2012]

But the thing is, viruses do.

It's hard to really clarify that. They might need a living host cell, but when they have one, they "do." They act. They take initiative.

Like I said, if you give a rock a living host cell, it won't do anything. It will be a rock.

Is a virus more alive than a rock? If it is, doesn't that mean it is alive?

Yes but this is more perception. They seem to react but it's simple chemicals coming into contact with other chemicals which causes chemical reactions.
They don't in any way think to react.

not the best example but i'm tired and going to bed after I hit the post reply button

Natrium stays dormant when properly preserved (surrounded by oil) but when it comes into contact with air it starts to react.
viruses have certain molecules on their protein capsules which when they come into contact with the molecules in a cell membrane causes a series of chemical reactions which allows them to enter the cell.

Another series of reactions caused by contact of molecules dissolves the proteine capsule, The free drifting rna or dna get's absorbed by the nucleus and hencefort the nucleus will continue to follow the instructions it contains.. which are now the ones from the virus' rna/dna.

viruses not being concidered alive is not persay my own opinion and it's a concideration anyway. based on observed behaviour. It's best treated on a molecular level then as a life form. e.g. trying to know why a virus wants humans instead of pigs will bring you nowhere because it's (bio)chemical compatibility not a choice or preference or somesuch which are things we associate with our idea of living things.

On a funny note though fire shares more characterics of the classic definition set for life then viruses

The number of complex chemical reactions to amount to complex behaviour seems to be the definition of life nowadays imho. What that number is. You tell me.

My personal opinion:
To be alive to me you need to observe and actively react to your surroundings. And I mean psychology react, a simple chemical reaction or nano mechanical result will not do for me.
Very basic lifeforms have this trait. Viruses do not. I haven't seen a virus be curious about anything or swim a little or be lazy. They are just inanimate untill they come into contact with the right stuff.
For me there is Life life.. as in things that are living a life. and you have advanced molecules and nano structures which are a level above totally inanimate material and a level under full flung life. I think the distinction is important.
Difference between life and living. If life is rna and dna.. then sure viruses are life. But are they living it?

Just my 2 cents and now i'm off for some much needed sleep.

[edit on 26/5/2007 by David2012]

what came first living cells (bacteria) or virsus?
Anyone know?
Either way they seem part of life!
And they are not inanimate, just dormant, big difference.

Man, this is one strange thread.

Are we possibly confusing or conflating the scientific definition of 'life' with 'intelligent life' or with 'biological'?

Or, are we trying to redefine or dispute the scientific version of the definition of life?

Viruses are considered to be 'biological'. There is debate on whether they are living or non-living.

Prions are certainly a clear example of something that is biological and not something that's part of another organism (such as a cell nucleus, or mitochondria), yet it is not considered 'alive'.

I think it's OK to be 'unsure'. After all we have some species that it's not clear if they're plant or animal or fungi (Protists are one, some having animal, some having plant and some having more fungi-like characteristics; thus they're given their own class).

I think we could make a case for something being 'alive' rather than 'inert', but does that serve any purpose; perhaps, but I'm not clear what.



[edit on 27-5-2007 by Badge01]