Virus=Life?

[Donut.Hole]

Are viruses alive?

 

Consider the following:

Living things

-Use energy (food)

-Move on their own

-Reproduce on their own

-Exchange gases (breathing)

-Respond to stimuli

-Grow

-Make waste

 

Viruses can respond to stimuli (hijacking a cell) and kind of reproduce by forcing the cell to do it, but now on their own. Some scientists say they are alive, some say they can't be because they don't fit all the criteria.

 

What's your view?

[thedarkshade]

What's your view?

Superposition>

[PhDP]

I never liked this life/non-life dichotomy, viruses have some of the important characteristics of life, but they're also missing some (i.e.: they can't reproduce on their own).

 

I don't feel the need to classify them either as living or nonliving; viruses are somewhere in between (IMO, closer to living systems).

[Donut.Hole]

I don't feel the need to classify them either as living or nonliving; viruses are somewhere in between (IMO, closer to living systems).

 

A worthy response. But I'd classify them as closer to non-living. They are simple capsules with DNA in them. The only thing they do is execute programed instructions when ivading a cell.

 

What do you think, eh?

[Daecon]

I think of them more as programs than as lifeforms.

 

I'm not sure what quantifier would be best, though.

 

Biological programs? Chemical programs? Molecular programs?

 

None of those phrases are really satisfactory.

 

Genetic programs?

[antimatter]

Sounds more like a biological program to me, but I might be wrong.

[Daecon]

I'd have put "biological program" as something like The Four Fs: Feeding, Fighting, Fleeing and Mating.

[antimatter]

Okay then, you're right, what do you think?

It's not really a genetic program though

[thedarkshade]

It's not really a genetic program though

Why wouldn't it be? After all it is genes that control nearly all the stuff!

[raspotin]

i think it's closer to living forms

but it's not living form exactly i think it's like aring between

the living and non living

some things is more simple than virus like prions

ohm half life form it's my point of view

[dichotomy]

(i.e.: they can't reproduce on their own).

 

Can you?!

[SkepticLance]

This is another of those terrible questions that can be answered either way depending on whose definition you use.

 

The old style definition of life, listing characteristics such as movement, reproduction, excretion, nutrition etc., cannot be used, since a forest fire has all those and is not living.

 

In a book on microbiology I was reading recently, life was defined as having three characteristics.

1. Reproduction

2. Evolution

3. Being based on a complex system of organic molecules.

 

Number 3 was included to exclude certain computer programs. However, some people use that quality to also exclude viruses.

 

My own view is that viruses are living. One reason is that there is a very strong possibility that some, if not all, viruses 'devolved' from simple parasitic bacteria. If so, are we to say they were living, and at some undefinable time through evolution became non-living? That, in my opinion, is a ridiculous position to take.

 

My own definition of life would include reproduction by replication of nucleic acids, and evolution by changes in those nucleic acids. This would comfortably exclude computer programs and forest fires, and include viruses.

 

It would exclude certain speculative forms of life on alien planets. However, I do not feel that a definition of life has to include all possibilities until those are found to be real. It just has to include what we currently know to be real.