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C'jais
01-30-2003, 02:08 PM
What is life?

Anything that breathes?

Anything that can reproduce on itself?

Anything with brain activity?

I'm making this thread only because some people in the abortion debate seem to have really weird ideas on this. I'm looking forward to your definitions.

ShockV1.89
01-30-2003, 02:24 PM
Anything with brain activity. That's brain activity down to the lowest level. So if a sperm fertilizes an egg and it begins to replicate itself but does not develop neurons and nerves and the beginnings of a brain, then it's not alive yet (imo).

Luc Solar
01-30-2003, 03:56 PM
Life = mental awareness.

Hmm..no wait... uh...I don't know. Tough Q! :D

C'jais
01-30-2003, 05:00 PM
If life equalled mental awareness, the logically next question would be "what is mental activity?". A brain? A soul?

But nevermind, let's go with that definition for now. By doing that, we're implying that single celled organisms and plants aren't alive. Hmmmm.

Are viruses alive? They don't breathe, metabolize, eat, move or excrete and on top of that, they can even be crystallized like other non-living chemicals. Yet they can self-replicate, parasitize and consists of nearly the same proteins and nucleic acids as we. To me, they are neither dead or alive.

Breton
01-30-2003, 05:25 PM
Ah, this was a hard one. But the best answer would probably be "All that reproduces naturally". That would cover most of life.

C'jais
01-30-2003, 05:30 PM
Originally posted by JM Qui-Gon Jinn
Ah, this was a hard one. But another answer may be "All that reproduces naturally". That would cover most of life.

Which leads to the question of just what naturally means.

Can robots and A.I. fit under this as well, if they ever get developed to the stage of where they can reproduce themselves?

And what to do about those pesky chemical reactions that just multiply and multiply when coming into contact with other materials? To me, they seem awfully alive.

How about galaxies and star systems? They reproduce naturally as well, no?

Breton
01-30-2003, 05:45 PM
Originally posted by C'jais
Can robots and A.I. fit under this as well, if they ever get developed to the stage of where they can reproduce themselves?



Machines making machines wouldn't fit under my opinion of "naturally".

How about galaxies and star systems? They reproduce naturally as well, no?

Do they? Cool.


But would the defenition "everything with their own DNA" cover life?

C'jais
01-30-2003, 06:00 PM
Originally posted by JM Qui-Gon Jinn
Machines making machines wouldn't fit under my opinion of "naturally".

But why isn't it naturally? Think of how life, as we know it, was perceived when it first originated 4.5 billion years ago. Regarded by all the non-organic materials around it, "life" would seem abhorrent - unnatural.

But would the defenition "everything with their own DNA" cover life?

Teehee. Virus do not have DNA. Are they alive?

DNA do not take care of reproduction. DNA only makes sure your offspring share the same traits as their parents. If this can be acheived by some other means - such as binary code in A.I. - then it would still be alive, no?

Reborn Outcast
01-30-2003, 11:11 PM
Originally posted by C'jais
Anything with brain activity?

I'm making this thread only because some people in the abortion debate seem to have really weird ideas on this. I'm looking forward to your definitions.

Uh-Oh... :D C'jais somehow I think this is going to turn into one of our littel matches with just you and me. :)


I believe that life is (going back to the abortion thread :D ) ANYTHING that is different from its parent. Once it becomes different (ex. the combination of X and Y chromosomes forming a fetus) then it is life.

Breton
01-31-2003, 05:41 AM
Originally posted by C'jais


Teehee. Virus do not have DNA. Are they alive?

D

Well, they do have DNA/RNA. But they aren't really alive either, as they are totally dependent on cells to survive, it can't live an independent life.

http://www.hiv-informanten.com/forskning/hva_er_virus.shtml

griff38
02-01-2003, 04:15 PM
quote:
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Originally posted by C'jais


Teehee. Virus do not have DNA. Are they alive?

D
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Well, they do have DNA/RNA. But they aren't really alive either, as they are totally dependent on cells to survive, it can't live an independent life.

That's True but I think the ability to replicate part of the self is the key. A virus does have RNA and even though it needs a host cell it still replicates part of itself in a new generation. (for me thats life)

I read recently some theoretical biological anthropologist believe viruses where once a complete lifeform that gave up their ability to pass on DNA in order to survive an extreme enviromental change. Settling instead for a more parasitical existance to ensure survival.

C'jais
02-01-2003, 04:28 PM
Originally posted by JM Qui-Gon Jinn
Well, they do have DNA/RNA. But they aren't really alive either, as they are totally dependent on cells to survive, it can't live an independent life.

Yes, they do have RNA (some have DNA, as well - I lied).

But the point is, DNA is just a code. It's nothing special in that sense. You could use binary code or anything else that fits the purpose.

I was once given a definition by old biology teacher:

It must be able to reproduce

It must be able to metabolize

It must be able to move

It must be able to evolve

Virus are bordering on life and death. They are neither alive nor dead - they can reproduce, parasitize and evolve, but nothing else really.

griff38
02-02-2003, 01:35 AM
Originally posted by C'jais
But the point is, DNA is just a code. It's nothing special in that sense. You could use binary code or anything else that fits the purpose.




Your correct, are you familiar with Prions? They are proteins that exist in the brains of all mammals. Under certain conditions if prions are exposed in someway to other prions from another mammal species, they begin a form of self replication extremely similar to the way a virus replicates. They begin a runaway reproduction cycle, this is what causes mad cow disease. Mass areas of brain tissue are destroyed being used to create Prions.
They seem to meet most of the criteria of a lifeform except no one can detect any Dna or Rna. They have some yet detected way of passing on part of their self to a new generation.

Bilbo Skywalker
02-18-2003, 08:55 PM
i think something is 'alive' if it needs water to sustain itself.

Reborn Outcast
02-18-2003, 09:07 PM
Originally posted by C'jais
It must be able to reproduce

What if it's a sterile woman. Is she not alive?

Originally posted by C'jais
It must be able to metabolize

Agreed

Originally posted by C'jais
It must be able to move

Plants?

Originally posted by C'jais
It must be able to evolve

I have no comment. :D

EDIT: C'jais I am unclear on if you were talking about cells or actual animals/plants/anything alive. I was assuming that you were talking about EVERYTHING. Please correct me if I was wrong in assuming that.

Originally posted by Bilbo Skywalker
i think something is 'alive' if it needs water to sustain itself.

By sustain do you mean thirst? Or need water in order to produce Hydrogen in order to make NADPH, NADP Glucose and all that other stuff.

Psydan
02-18-2003, 10:51 PM
~The property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism.
-American Heritage Dictionary

Well, my first thought was "well what if a certain person just can't reproduce, or just choses to never reproduce, are they not alive? Can I murder someone who doesn't have the ability to reproduce?
But, whoever said that one thing had to be different from its parents, what about clones, or animals that reproduce asexually? Also, I wasn't quite clear on what traits viruses don't posess...
Remember, just because it's not the same as you, doesn't mean it's not alive.

Pnut_Man
02-18-2003, 11:08 PM
I don't think the ability to reproduce has anything to do with one being "alive".

What it comes down to (in my opinion) is that the being can perform mental activity...I realize that this is harder to define than it seems..damn :P

Anyway, I don't think viruses are alive, they just mimic life very very well.

Psydan
02-18-2003, 11:15 PM
Originally posted by Pnut_Master
I don't think the ability to reproduce has anything to do with one being "alive".

What it comes down to (in my opinion) is that the being can perform mental activity...I realize that this is harder to define than it seems..damn :P

Anyway, I don't think viruses are alive, they just mimic life very very well.

But not all living things have brains, and what about things with the POTENTIAL for brain activity, are they only alive when they first have it?

C'jais
02-19-2003, 09:29 AM
Originally posted by Psydan
Well, my first thought was "well what if a certain person just can't reproduce, or just choses to never reproduce, are they not alive? Can I murder someone who doesn't have the ability to reproduce?

You guys are taking this crudely literal.

We're talking about living things on a species level.

No, a sterilized woman cannot reproduce, but the entire human species most certainly can. No, the individual plant does not appear to be able to move in any way, but it most certainly can when you see how it can cover a huge area, how it can spread its spores to new areas and how it can burst through asphalt.

ShockV1.89
02-19-2003, 09:59 AM
Originally posted by Psydan
But not all living things have brains, and what about things with the POTENTIAL for brain activity, are they only alive when they first have it?

Potential for brain activity does not equate to brain activity. I have the potential to get sick. But I'm not sick yet. Does the fact that I have the potential to get sick default me to sick status? No, of course not.

Life isnt living until the brain activity is there. Until then, it's a lump of organic matter.

Reborn Outcast
02-19-2003, 01:37 PM
Originally posted by C'jais
No, a sterilized woman cannot reproduce, but the entire human species most certainly can. No, the individual plant does not appear to be able to move in any way, but it most certainly can when you see how it can cover a huge area, how it can spread its spores to new areas and how it can burst through asphalt.

So now you're talking about a species as a "whole?" Just tryin to get this straight becasue I don't necessarily agree with what your old bio teacher said. :D Was he/she saying that, in order to live, an organism must be able to do ALL those things or just 1 or 2?

ShadowTemplar
02-20-2003, 11:43 AM
Originally posted by Reborn Outcast
I believe that life is (going back to the abortion thread :D ) ANYTHING that is different from its parent.`

Carbondioxide is different from its "parents" (ie oxygen and carbon). Does that make the carbondioxide living? Methinks not.

Your correct, are you familiar with Prions?

[...]

They have some yet detected way of passing on part of their self to a new generation.

Damn! I was gonna say that!

Was he/she saying that, in order to live, an organism must be able to do ALL those things or just 1 or 2?

Having had the same teacher I can safely say that he said all of them. But again, you will have borderline examples.

BTW: I don't remember the part about evolving? Then again I only remember four of them (the last one being the possession of DNA), and I distinctly remember that there were 5.

But what if you came across a race of machines, the legacy of another race that was long gone? What if they had social structures like humans? Emotions like humans? What if (using sophisticated technology) they even reproduced almost like humans? But they had no DNA? Would they not be alive?

What I am trying to say is that there will always be borderline examples.

Another one: A dead body, at the exact moment of death, has all the vital parts needed to continue living, but it doesn't, and we know quite distinctly that it doesn't. What is it that makes it 'dead', rather than 'alive'? And please don't go on with some 'soul' rubbish.

Bilbo Skywalker
03-08-2003, 07:46 AM
~The property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, and response to stimuli or adaptation to the environment originating from within the organism.

doesnt fire have all these qualities, yet we do not say that fire is 'alive'


quote:
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Originally posted by Bilbo Skywalker
i think something is 'alive' if it needs water to sustain itself.
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By sustain do you mean thirst? Or need water in order to produce Hydrogen in order to make NADPH, NADP Glucose and all that other stuff.

ok, what i meant is 'to sustain its current state'.

ie if a plant doesnt intake water, it will rot away, ie be dead, ie not be in its previous 'state'. Same goes for human beings, and all other species on earth.


:wavey:

FunClown
03-08-2003, 09:18 AM
Probably as something that can reproduce, has DNA etc. Something that develops over time, and has some overall purpose about it, which it achieves primarily on its own (growing, surviving). But please remember this is very abstract. DNA can still exist in a creature not living. And some creatures may not be able to reproduce (eg sterility).

Remember also that not all life has a brain, this includes Jellyfish. Which is 98% water. Interestingly enough.

ShadowTemplar
03-12-2003, 02:28 PM
Originally posted by Bilbo Skywalker
doesnt fire have all these qualities, yet we do not say that fire is 'alive'

No, fire doesn't fulfill the last criterium. It doesn't change or in any way adapt to its evironments. Besides the definition applies only to matter. Fire is usually defined as the heat and light generated by rapid oxidation of inflammable material, and as such is not matter but rather electromagnetic radiation.

[QUOTE]Originally posted by Bilbo Skywalker
[B]ok, what i meant is 'to sustain its current state'.

A water-cooled computer "needs water to sustain its current state" (ie not burn down). NaCl(aq) needs water to be present for it to maintain its current state.