Defining Life: The Debate Over Whether Viruses Qualify

[DaveC426913]

Wouldn't this mean that no parasites are living?

Parasites are still living creatures when they're not parasitizing. Phoenix's definition is too broad.

If I understand correctly, viruses are chemically inert when they're not in a cell.

 

[mgb_phys]

If I understand correctly, viruses are chemically inert when they're not in a cell.

Viruses are just a length of DNA (or RNA) with a sugar coating.

A similair problematic example is mitochondria, they exist in all our cells, but they have their own DNA and their own evolutionary history. They are probabaly originally bacteria that were absorbed into the first cells.

Since we can't live without them I suppose mitochondria could argue wether people are really alive!

 

[DaveC426913]

Since we can't live without them I suppose mitochondria could argue wether people are really alive!

There's a definite line between:
- organisms that metabolize by parasitizing off other organisms and, denied those other organisms, will sooner or later die
and
- virii that do not metabolize at all on their own

See, it's not that virii "can't live without a host" it's that virii do not live absent a host. They're inert.

 

[ViewsofMars]

Wouldn't that mean they are just pseudo life, in that they cannot live on their own? I would say viruses weren't living things but rather a type of false life as they can't live without infecting a host organism.

If you are implying that a virus is a pseudo life then I would say "no" because "pseudo" implies false or fraudulent such as pseudoscience.

Let's examine this closer.

Virus - An infectious microbe that requires a host cell (plant, animal, human, or bacterial) in which to reproduce. It is composed of proteins and genetic material (either DNA or RNA).
http://publications.nigms.nih.gov/thenewgenetics/glossary.html

What is a Microbe? You may next ask. Here is an excerpt from a larger article that can be helpful:

Microbes are single-cell organisms so tiny that millions can fit into the eye of a needle.

They are the oldest form of life on earth. Microbe fossils date back more than 3.5 billion years to a time when the Earth was covered with oceans that regularly reached the boiling point, hundreds of millions of years before dinosaurs roamed the earth.

Without microbes, we couldn’t eat or breathe.

Without us, they’d probably be just fine.

Understanding microbes is vital to understanding the past and the future of ourselves and our planet.

Microbes <my-crobes> are everywhere. There are more of them on a person's hand than there are people on the entire planet!
Microbes are in the air we breathe, the ground we walk on, the food we eat—they're even inside us!
http://www.microbeworld.org/microbes/

Now here is something very interesting from MIT, Volume 53, Number 21, Wednesday, April 8, 2009, TechTalk, Article VIRUS: New battery, built with bacteriophages, could power cars, electronic devices by Anne Trafton News Office by Anne Trafton - FANTER Researchers at MIT have found a way to use benign viruses and nanotubes to create high-powered batteries.(VIRUS, PAGE 5)

Here's an excerpt from that article:

... MIT Professor Gerbrand Ceder of materials science and Associate Professor Michael Strano of chemical engineering, genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material.

Because the viruses recognize and bind specifically to certain materials (carbon nanotubes in this case), each iron phosphate nanowire can be electrically “wired” to conducting carbon nanotube networks. Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time.
The viruses are a common bacteriophage, which infect bacteria but are harmless to humans.
http://web.mit.edu/newsoffice/2009/techtalk53-21.pdf

Learning is great fun! :!) it and your world will sparkle.

p.s. Dave, looking up at you. I really like your signature! Yee gads, I can't stop chuckling. Thanks!

 

[Phrak]

What are the distinguishing characteristics that would tell us that a tobacco mosaic virus is a living thing and that a mineral crystal of any sort is not?

 

[DaveC426913]

p.s. Dave, looking up at you. I really like your signature! Yee gads, I can't stop chuckling. Thanks!

Glad to know someone finally appreciates it...

 

[ViewsofMars]

I sure do. Thanks again. It's time for me to leave the virus issue. I got the giggles.

 

[CRGreathouse]

If you are implying that a virus is a pseudo life then I would say "no" because "pseudo" implies false or fraudulent such as pseudoscience.

Pseudopod, pseudonym, pseudocode? I don't find false/fraudulent to be the dominant meaning of the English prefix, Latin roots notwithstanding.

 

[philnow]

Yes. Without a host, they do not metabolize at all; they are nothing more than fragments of DNA in a shell. (Caveat: My facts may be out-of-date and this may be oversimplifying.)

But they literally just expose their DNA to the host, that's certainly not metabolism. If a puzzle lands in my room and I follow the template and re-arrange the puzzle into another form (say that a part of the template was for me to copy it several times), I wouldn't say that the puzzle took any action :P

 

[DaveC426913]

But they literally just expose their DNA to the host, that's certainly not metabolism. If a puzzle lands in my room and I follow the template and re-arrange the puzzle into another form (say that a part of the template was for me to copy it several times), I wouldn't say that the puzzle took any action :P

Agreed. Which is why I'm arguing that virii are not life.

 

[DaveC426913]

Pseudopod, pseudonym, pseudocode? I don't find false/fraudulent to be the dominant meaning of the English prefix, Latin roots notwithstanding.

Regardless, that is simply a semantics issue. It doesn't help define if virii are life, it simply creates a third label.

 

[ViewsofMars]

Are viruses life?

The American Society for Microbiology says:

When is a life form not a life form? When it's a virus.
http://www.microbeworld.org/microbes/virus/default.aspx

p.s. Dave's signature is invisible unless you are a member who has logged on. I can't stop laughing! Dave, come on, share your *bug* with those who aren't members. (tee hee)

 

[Lancelot59]

Whether or not viruses are alive is a matter of opinion. If you take a look at biology on a lower level, 'life' as we commonly define it is just a series of chemical reactions. Life itself following Opram's Hypothesis (I probably misspelled that) say that life was just a coincidence. The right conditions at the right time.

Personally I say they aren't alive. They are not capable of carrying out any of life's functions on their own. They are just particles that float around, and when they bump into a cell the DNA release process is triggered. They can't move or do anything else on their own. They just drift along and happen to infect cells along the way.

 

[Ophiolite]

It is quite irrelevant whether they are alive or not, since as several have pointed out that is matter of semantics, not science. It will make no difference to their behaviour, evolution, or what we learn of them whether they are alive, dead, or in some half way house.

 

[philnow]

Well, obviously, but it's still a classic debate.

 

[Lancelot59]

Why don't we just call them something in between? Like zombies? Not living but not dead.

 

[byohannan]

Life is a borderline unit of lifeform. The exactly sit the border of the quick and the dead.

they do reproduce using a host cell
they are self contained
they mutate
they understand the presence of a potential host cell

 

[byohannan]

Yes viruses are a lifeform .So also were the their rudimentary predessors who were capable of self sustaining and duplication

 

[DaveC426913]

Life is a borderline unit of lifeform. The exactly sit the border of the quick and the dead.

they do reproduce using a host cell
they are self contained
they mutate
they understand the presence of a potential host cell

They are not self-contained. The virus unit itself is not enough to metabolize or meet most of the other criteria for life.

They do not "understand the presence" of a potential host cell. The chemistry to enter a cell either works or does not.

 

[2kbucks]

First I'd like to point out (as I believe it was touched on already) that no 'life' can truly survive on its own. And I believe that even humans could be considered 'parasites' in the 'host cell' that is the Earth. ie we cannot preform basic life functions 'outside' our ideal environment. (spaceships aside) considering this I'd say that maybe viruses are more alive than us because some could survive outside their environment until they return to one, giving them better survival ability.

Second, I like to ask what's the point of life? Aside from all Philosophical debate, I believe the evolution and passage of our DNA to be the primary objective, as all or most criteria for life are based around this ability. Which viruses do. I think the fact that it's pretty much all they do just makes them the simplest and most efficient form of animated matter or life.

Lastly, I'm pretty sure that virii is the plural for the Latin Vir which means Man. So I'm also pretty sure it's viruses!

 

[kuzao]

the definition i like and which makes sense to me is (as far as we talk about Earth based biological life):

the ability to ranscribe and translate.

or even better: the presence of DNA and RNA at the same time

until now i nerver saw a better definition.

of course you can wander in the philosophical realm and talk about abilities, intend... blah blah. but this short and 'hard' definition i prefer.

a virus doesn't have the ability to transcribe and translate. same goes for dna and rna.

alex

 

[DaveC426913]

the presence of DNA and RNA at the same time

But this is not a definition. You've found common properties, granted, but that doesn't define life.

 

[kuzao]

dear dave,
you are just arguing semantics!

are you unsatisfied with the grammar of my statement? should i rather say
any entity that contains dna and rna at the same time is to be called life?

or how about 'life:things transcribing and translating'

i do not think that your point is valid. that is as long as we talk about a biological definition of live. as soon as you want to argue the philosophical side you might be right. but then on the other hand your previous attempt to define life would look rather clumsy.

from your previous posts i get that you do share my view, so could you tell me what you dislike about my definition?

by the way last time i checked the molec. micro biology books i usually use called viruses infectious particles.

oh and another thing: until now i met nobody who uses virii. which might be also based on the fact that -ii is the ending for F. and M. latin words ending on -ius. which would naturally mean that virii is nonsense. (that so as long as you don't write normally virius)

alex

 

[DaveC426913]

dear dave,
you are just arguing semantics!

are you unsatisfied with the grammar of my statement? should i rather say
any entity that contains dna and rna at the same time is to be called life?

No, I'm unsatisfied that this defines (Earth) life.

Hm. Let me compose my argument...

or how about 'life:things transcribing and translating'

No. Far too vague. Lots of artificial non-living things transcribe and translate.

 

[kuzao]

hmm i wonder what non living things you are referring too when you say there are some which transcribe and translate?

 

[DaveC426913]

hmm i wonder what non living things you are referring too when you say there are some which transcribe and translate?

Computer programs for a start.

 

[junglebeast]

are you unsatisfied with the grammar of my statement? should i rather say any entity that contains dna and rna at the same time is to be called life?

Understanding the function of DNA makes it obvious that DNA itself is not necessary for life. It's role is simply to store information in a way that can be copied to allow evolution to occur. DNA is certainly not the only molecule that could potentially fill this purpose.

I believe there has been at least one organism identified on Earth that does not use DNA, although I can't remember the name of it. Anyway, life on other planets almost certainly will not use the exact form of DNA as here on Earth. Moreover, there is no fundamental reason why life must be molecular at all. Life could theoretically be formed out of sub-atomic particles, or even out of virtual building blocks in a computer.

 

[DaveC426913]

DNA is certainly not the only molecule that could potentially fill this purpose.
...
Anyway, life on other planets almost certainly will not use the exact form of DNA as here on Earth. Moreover, there is no fundamental reason why life must be molecular at all. Life could theoretically be formed out of sub-atomic particles, or even out of virtual building blocks in a computer.

All of which I would agree with, if he hadn't qaulified it by saying Earth life.

 

[BoomBoom]

Understanding the function of DNA makes it obvious that DNA itself is not necessary for life. It's role is simply to store information in a way that can be copied to allow evolution to occur.

That is most certainly not the only function of DNA. DNA is essential to cellular function.

Anyway, life on other planets almost certainly will not use the exact form of DNA as here on Earth.

How can you be so certain? The "central dogma" could very well be universal...across the universe. Until we actually find extraterrestrial life, the words "almost certainly" has no substance to it whatsoever.

 

[junglebeast]

How can you be so certain? The "central dogma" could very well be universal...across the universe. Until we actually find extraterrestrial life, the words "almost certainly" has no substance to it whatsoever.

The same way you can be certain than 10 = x + y has multiple solutions. No experiments are necessary once you understand addition...