Defining Life: The Debate Over Whether Viruses Qualify

[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 (Caveat: My facts may be out-of-date and this may be oversimplifying.)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...

 

[kuzao]

@ dave
while we seem to agree on the answer our way of comming ot that conclusion seem to be different.

no offense meant but could it be that it is a while ago since you studied molecular biology?

as for transcription and translation, i used these as biological terms. they are defined as coppying dna to rna and then making poly peptides out of rna.
this means that there are actually no artificial 'things', entitys or what ever who translate and transcribe.

@ jungle beast

im not aware of any organism who doesn't contain dna. could you find the name? I am curious.

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.

first: of course its not the only molecule but its is certainly the only for EARTH based BIOLOGICAL (some call it organic) life. and that was as, dave pointed out, exactly what i said. are we trying to define what we have here based on 'hard' definitions or are we trying to be philosophical? there is nothing wrong with that, but then the defintion would be so much longer and 'softer'.



second: again there is no offense meant when i say: you didnt had any molecular biology classes, or?
boomboom is right when he says that dna's task are many and not limited to only storing information. expression regulation by dna folding, dna binding and many more ways is big topic in mole. bio.

i do not totaly agree with boomboom on his 'central dogma' theory.
yes it MIGHT. but it might also NOT. we can't say and i proclaim we will never find out because that would require to locate and analyse ALL life (and i mean ALL! not only on Earth or in this galaxy) hencefore this is a irrelevant point and futile to discuss.


one thing we should have a common understanding of is the term 'definition'. do we want something which desribes the essence, the principle of life or do we want a definition as lawyers tend to make them ^^ loooong, wound in strange shape so that every possible and impossible exeption is included and useless? (this time the offense to lawyers is intended :P )

alex

p.s. sry for the typos. being dyslexic AND tired is fatal ^^

 

[DaveC426913]

as for transcription and translation, i used these as biological terms.

Which is a circular argument.

Basically your argument boils down to "life is that which performs biological functions".

 

[DaveC426913]

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.

Because amino acids can form a nearly infinite variety of proteins. For DNA to arise the same twice - let alone common - is astronomically unlikely.

Personally, I think it will be very similar, but not the same.

 

[kuzao]

@dave

oh far from beeing true. my statement could be read as 'life is what is based on these two functions' (still doesn't sound flashy)

one could see it as a circular argument IF these were the only functions present in organism and thus they could be called the only biological functions.

maybe i should have explained more.
transcription and translation are terms closely realted to presence of rna and dna. thus saying transcription and translation is defining life means presence of dna and rna is defining life.

does this make it more clear to you? do you see now that this is not a 'soft' argument but a very ahrd one? and also not a circular one?

 

[kuzao]

Because amino acids can form a nearly infinite variety of proteins. For DNA to arise the same twice - let alone common - is astronomically unlikely.

Personally, I think it will be very similar, but not the same.

first i think its futile to find a defintion for something we don't even know about yet. that's just discussing because we like to read our on writings...

however i agree on the point that it is unlikely. to be exactly the same. but how exactly the same does it has to be to be still called dna? what if it incorporates uracil instead of thymine. could i then still be called dna?

i assume dave then would argue that its not the same thus he was right while boomboom would say hey look it basically the same?

lets don't wander into that realm. there is no merit there.

 

[DaveC426913]

@dave

oh far from beeing true. my statement could be read as 'life is what is based on these two functions' (still doesn't sound flashy)

one could see it as a circular argument IF these were the only functions present in organism and thus they could be called the only biological functions.


maybe i should have explained more.
transcription and translation are terms closely realted to presence of rna and dna. thus saying transcription and translation is defining life means presence of dna and rna is defining life.


does this make it more clear to you? do you see now that this is not a 'soft' argument but a very ahrd one? and also not a circular one?

No and no.

Translation and transcription do not define life. There are non-living things that translate and transcribe that have nothing to do with DNA or RNA. It is too general.

Your argument is the equivalent of:

All cars have motors. Therefore, the definition of a car is that which has a motor.

 

[kuzao]

as i said before transcription and translation are terms of molecular biology and in this context i used them.

do you understand what translation and transcription means?

there are no things which can translate and transcribe and are artificial (at least to my knowledge and if you don't purposly trying to ridicule my argument by saying that a vial where you put in some dna, rna, polymerase and other things should then be called life)

your car argument is a faulty one. if you understand the meaning of transcription and translation you will understand that all things which inherit these two abilities are life. while not all things inhereting a motor are cars.

if you define life via rna and dna or translation and transcription you will as a result get all the things who can 'do' the 'things' most people asscociate with life. like proliferation, metabolism and so on. which is in my opinion a reason to chose this defintion because it avoids to define something by some 'effect' but instead defines by source / reason.

alex

 

[DaveC426913]

as i said before transcription and translation are terms of molecular biology and in this context i used them.

OK, so let's make that context explicit.

"Life is that which performs biological transcription and translation."

That is circular.

 

[kuzao]

we are talking about viruses and life here of course taht implies that we talk biology here.

do you realize that transcription and translation are synonymes for the presence of rna and dna?

how can chosing the two elemental functions of an organism as lifes definition be a circle argument?


if your point would be valid that woul mean that you need life to define transcription and translation. but you dont.

translation and transcription are chemical processes. you do not have to use 'life' to define them. so how can this definition then be a circular argument?

by the way i feel sorry for the other discussion participants because we take up to much space. should we continue this conversation in skype or via email?

alex

 

[BoomBoom]

i do not totaly agree with boomboom on his 'central dogma' theory.
yes it MIGHT. but it might also NOT. we can't say and i proclaim we will never find out because that would require to locate and analyse ALL life (and i mean ALL! not only on Earth or in this galaxy) hencefore this is a irrelevant point and futile to discuss.

Well, I wasn't claiming that is was for sure, I was making the point that it could be...in order to counter the assertion by JB that it is "almost certain" that DNA from another planet would be different.

The true answer is we don't know, nor can we know until we find some...then we could start to make some educated assumptions perhaps.