What/who Is Alive

We all know what is alive (animals plants bacteria etc etc) and what is not (rocks water etc) but could anybody give a nice and precise explanation of what it takes to be alive (what are the minimum requirements to be considered alive)???

I am asking this because I see many people consider life (being alive) to be a really complicated thing to happen, and I am wondering that if we can't exactly explain what life IS, how can we understand how complicated it is to happen by chance or by accident.

PS: this is not a question of metaphysics (what is life's meaning etc etc) its a simple question with a hard answer. A definition of life (or being alive) if you want...

Well i'll tell you one thing.. FIRE IS ALIVE!!!! damn it people its alive :evil:

I mean c'mon people! It grows, it takes it oxygen and carbon for energy and releases carbon dioxide, it reproduces( yes it spreads and thgrows out sparks, it may rely on the wind for successful spreading but so what, its just an unusual asexual creature.

It usually doesnt spread to wet surfaces and hisses and goes away from water( yeah argue waht you want but its sentience damn it!)

eh it depends on your definition, we always apply ourselfs when we think of the universe, they may be areas were our rules of life simply dont apply.

http://en.wikipedia.org/wiki/Life

Google is your friend ^^

And so is Wikipedia ^^

from the wiki article:

There is no universal definition of life; there are a variety of definitions proposed by different scientists.To define life in unequivocal terms is still a challenge for scientists


so what I am asking is what people think.

I have to say that you have a point with fire... (i guess it could maybe be though as a "pure energy" life form).

My question is: Someone says that FIRE IS ALIVE. how can he prove it or how can we disprove it if we dont know what ALIVE means?

PS: you dont need to be able to reproduce to be alive (eunichs as well as mules are very alive and very sterile)- you dont need to be sentient to be alive (bacteria dont have a "brain")
PPS: I think the best argument of the article would be Metabolism... (Living things require energy to maintain internal organization)

Self-Aware
Aware of one's own Mortality (assuming the entity is mortal)

A plant is a living creature, but it isn't so much alive.

There are a lot of organisms that scientists would consider to be alive even though they may not be self aware. Plants being just one example. Germs and cells are considered as living beings and I highly doubt that they are really self aware. Though, I suppose anythings possible. What I don't understand is why scientists don't count viruses as being alive even though normal cells are.

people argue that plants arent self aware as meaning they are only half living. I guarantee you not a single vegetable wanted to die for your salad. anyone who grows plants know that plants will actually 'struggle' to stay alive. having grown several tropical plants myself, I can tell you plants have a natural will to stay alive - showing on some level of consciousness *even if its not a consciousness that says 'I'* it knows it can die.

do plants know their own mortality? I think so. There is enough evidence showing they want to live. I think plants are most conscious on its own death bed, as well as most living things. The idea that a living thing will do anything to stay alive and not realize it can die, doesnt make a whole lot of sense to me, its not even logical. The only reason why we reason a living thing will do anything to stay alive and still be mindless of its own mortality is becuase it doesnt have a brain. But seeing as how weve yet to define consciousness, how do we know its the result of having a brain???

When you really think about it, the knowledge that your existance can end almost seems to be the very drive in ALL living things on earth. Everything we do all stems from this drive of death. We live becuase of death. At least, thats how the mortal life is.

people also compare plants to mindless bacteria as another way to show how its only half living. but that isnt entirely fair - plants are sophisticated organisms and they will out live humanity - and they are thousands of times more evolved than a single bacterium. Just look at a tree and try to put it on the level of a bacterium. What kind of mindless bacterium lives for hundreds of years and wieghs a ton? What kind of mindless bacterium out lives a human??? keeping that in mind, you should check out some of the crazy bacterium videos (as well as time lapses films of plants). :yumdumdoodledum: those little critters mindlessly swim around in circles bumping into things, over and over again! theyre quite active even if stupid.

I think our current definition of living things, or even our understanding of consciousness is off.

how self aware are you? are you self aware that you are breathing? are you paying attention to all the sensations of your body right now? of all of your thoughts? what were you thinking of just a moment ago? self awareness is apart of being alive I think - but even then I think there are dozens of different levels of self awareness. And very low levels of self awareness do not have an 'I'. And high levels of self awarness say "I AM"

we can compare self awareness to a dream. you can be dreaming and not be aware of your dream. you can still talk, still reason, still experience, but completely unaware of the reality of your surroundings, not aware of your own self other than your most immediete feelings and actions - in other words a lack of awareness of past and future. Is the dreamer aware why they even thought this or that?? and then what happens to your near mindless dream state? the dream starts to fade and you get this feeling, this feeling that its all about to end. and before the dream fades away from existance you finally realize "Im dreaming!"

I think this is what a low level of self awareness of life is like. That when death comes knocking you finally realize that you were. Thats why I say plants do have some level of awareness, because when death comes knocking on their door - they do not just sit there as you think do. They act, they react, they fight to stay alive. Eastern religions tend to refer to plants as a level of consciousness that is 'sleeping'.

Its hard for humans to imagine self awareness without an 'I'. But I think there is. Becuase 'I' isnt just self awareness but a statement of individuality. Since we are individuals, its hard for us to understand anything that shows no individuality - like plants. However, I do not think inviduality is apart of the living definition, just apart of a higher consciousness.



***************

edit: I know that some people are going to bring up the nervous system as an argument as to why plants are only half living. But its this mentality that stops us from understanding what makes a living thing living to begin with.

A nervous system is for animals only.

For example. Lets say you break your back. All of your nerves for everything below your waist is dead, gone, destroyed, cut off. What happens? You can no longer feel any stimuli below your waist. You can no longer react to any stimuli below your waist. Your brain can no longer send any messages to any part below your waist to move. Everything below your waist is lifeless.

So. . we ignorant humans conclude, a nervous system is necessary to 'sense'. We use this argument a lot that plants can not feel anything then.

However, we know for a fact that plants DO react to stimuli. If a human can not react to stimuli without a nervous system. . how does a plant? How does a plant move its body parts accordingly to stimuli without a brain?

I think we should toss out the age old belief that our nervous system is the only one.

Quote:

---

Originally Posted by sogart

PPS: I think the best argument of the article would be Metabolism... (Living things require energy to maintain internal organization)[/b]

---

What about viruses? They are just complex molecules that can't do anything on their own; they have to take over a cell to and then they just reproduce themselves. And prions, who don't do anything except cause other proteins to fold weird like they do.

In one way it is a spectrum, with viruses and prions in the middle, but you could argue that they came from "real" living things (viruses from escaped DNA, prions from mutated proteins) so they don't really count as seperate entities to be considered.

My guess: Generally anything that moves on it's own without the help of external forces.

Quote:

---

Originally Posted by petersonad

My guess: Generally anything that moves on it's own without the help of external forces.[/b]

---

erm.... *cough* trees *cough*

Yes, I would consider those alive as well.

There are some criteria... that we made up. There isn't a universal law that dictates what is life, and what not.

A few of the criteria are:

-Procreates
-Grows
-Feeds

And some more.

Bottom line: Everything that has cells is alive. Smallest bacteria and up. Viruses aren't counted in as 'alive', really on a monocular level they are Nothing, so they aren't seen as 'life'. (Viruses aren't even single-celled, they are less.)

well, I know about the 'classical' idea of "anything made of cells is alive etc etc" but there are some problems:

1) virii - a virus has no cells (they look like cells but they are only a cover for its genetic material) but I (and most people) would consider them living

2) extraterrestrial life? (I'm not saying it exists - but if we can think of life evolving somewhere else then there is no reason for it to be organized in cells as we have them here...)

3) other types of life? (artificial life?) knowing what life is could help us in the identification/creation of artificial life... what would it take for a (robot?) computer to become alive?

PS: I don't know if plants can "feel" etc etc, but I don't understand why somehting has to be sentient to be alive... I think this is a big misunderstanding. Intelligence is a different thing from Life.
PPS: some times the simplest questions are the deepest ones if you take a little more time to think about them (by the way WHAT IS TIME? just joking)

My best guess at an explanation would be:

something that is internally more highly organized than its environment and can sustain this organization actively

there are some problems with this explanation too though:

how can we judge organization levels? (maybe information? patterns? is a cell more organized than a rock or a crystal?)

how can we judge if it sustains it actively (growing, feeding, reproducing, homeostasis all fall under this)

any thoughts? (hope i'm not going to far and people can follow my argument)

Quote:

---

Originally Posted by petersonad

My guess: Generally anything that moves on it's own without the help of external forces.[/b]

---

Yes yes, i agree !
It sounds good, but then what about toy robots running on batteries? Or are batteries considered as external forces? Well what about some implanted solar panel then.
That is animated life. And then i wondered where is the line between animated and 'normally' alive ?

Quote:

---

Originally Posted by sogart

1) virii - a virus has no cells (they look like cells but they are only a cover for its genetic material) but I (and most people) would consider them living[/b]

---

What "most people" is this? A majority of idiots? If you presumed that virii were alive, you could reduce that further to prions - and their just proteins. Cells are more complex than a virus; are they then alive? Are we a conglomerate of alive beings?

I think also your seperation of sentience and life is odd; free will implies sentience; a non-sentient thing is thus just a deterministic (as far as the laws of physics allows) system. This computer is a deterministic system. Is it alive?

But now think of what we humans have to do as "a system". Pretty complex requirements, huh? Maybe sentience is just an illusion to help us - as a system - cope with the task - an interface if you will. Then if sentience is an extension of a system, maybe sentience is a system as well. So then, where does the life lie?

Trying to draw a line at living/non-living has no meaning in a fundamental level. A definition can of course help in everyday life, but it'll only ever be a definition.

So basically, this topic is purely about what we call life. How we define it. Does that matter? Bacteria are called life, no one ever felt bad about them. It doesn't really matter what you call life.

-

Also, a virus really isn't life. If you know what it is, how little molecules it is made of, you would probably agree.

Aliens quite likely will also have cells. With these rules of physics, it is Bound to be cellular life, nothing much different is possible.

A.I. but in a few decades, especially if it can reproduce, I personally do see as 'life'. However, I don't think anyone will feel bad over it's 'emotions'.

Quote:

---

Originally Posted by tyrantt23

erm.... *cough* trees *cough*[/b]

---

havent you ever seen a tree growing wonky, or totally on its side? becuase of tall buildings blocking sunlight from one angle a tree is forced to grow in a certain direction. sure, its slow, and we dont see the movement, but without the building being there it would have just grown straight up.


all plant life moves

Quote:

---

Originally Posted by joey11223

FIRE IS ALIVE!!!![/b]

---

Fire is born
Fire grows
Fire breathes
Fire consumes
Fire procreates
Fire dies

I could agree ;)

Quote:

---

Originally Posted by pawstalker

Yes yes, i agree !
It sounds good, but then what about toy robots running on batteries? Or are batteries considered as external forces? Well what about some implanted solar panel then.
That is animated life. And then i wondered where is the line between animated and 'normally' alive ?[/b]

---

I was somewhat expecting someone to take my guess into more detail. To ponder on it from a more detailed perspective: I was also trying to distinguish the difference between what would be considered an external force or something else. Such as the batteries for a robot vs. natural physical laws: osmosis. Let's say that if it moves by consciousness it's alive. Although that might not be able to be explained by science alone. You could observe the behavior of bacteria in response to certain conditions: such as the presence of light, temperature, and moisture. Such influences that cannot be explained by physics alone. Go figure.

Quote:

---

Originally Posted by Neruo

There are some criteria... that we made up. There isn't a universal law that dictates what is life, and what not.

A few of the criteria are:

-Procreates
-Grows
-Feeds

And some more.

Bottom line: Everything that has cells is alive. Smallest bacteria and up. Viruses aren't counted in as 'alive', really on a monocular level they are Nothing, so they aren't seen as 'life'. (Viruses aren't even single-celled, they are less.)[/b]

---

What about a mule? It is unable to procreate, so is a mule not alive? Same for any creature too young or too old to procreate. Are they not alive?

What about a star? It grows and feeds and creates heavier elements that become planets when it goes nova. Is it alive?

My pencil is made of wood. It has cells. Is it alive?

If you get a flu shot, you are being injected with the dead husks of a virus to help your body build an immunity to it. They are "dead" husks which means they were formerly alive. Viruses live and die.

Bottom line: You don't know what the bottom line is. Defining what "life" is is extremely tricky.

Quote:

---

Originally Posted by sogart

We all know what is alive (animals plants bacteria etc etc) and what is not (rocks water etc) but could anybody give a nice and precise explanation of what it takes to be alive (what are the minimum requirements to be considered alive)???[/b]

---

Maybe it's so hard to define because everything is alive. I have no scientific basis for that statement and I don't feel bad about kicking a football because 'it's alive' either. I just think everything is alive.

Must have some way of multiplying barring sterilization. (Mules are sterile but alive, but viruses require a host so they aren't)

Must metabolize something.

Can die.

Must be made out of cells, which also satisfy all 3 other criteria.



I can't think of a counterexample to this group.

Quote:

---

Originally Posted by ninja9578

Must have some way of multiplying barring sterilization. (Mules are sterile but alive, but viruses require a host so they aren't)

Must metabolize something.

Can die.

Must be made out of cells, which also satisfy all 3 other criteria.
I can't think of a counterexample to this group.[/b]

---

Good job! Aside from viruses, those are the main criteria for life: Cells, metabolism, self-generation (either created by a self-generation process or is itself capable of it). And while the "it can die" aspect seems like a strong argument, it's essentially saying that something is alive because it's alive (not dead).

Viruses are special in that while they exhibit some signs of being a lifeform, they do not have DNA structures and cannot reproduce themselves without a host. Essentially they hijack a cell's system to replicate itself. Yet a virus can be killed. They were not always considered life - they are really just nucleic acids and proteins - but nowadays bioligists tend to categorize them as "semi-life". In short, they are a special case.

edit: I mispoke. Viruses do have DNA. Sorry.

I think we have quite a good argument going on until now on what is life, and I want to stop for a second in one or two points that surprised me. I don't remember who said what but it doesn't matter:

1) If something is alive we should respect it (or as someone said I think a ball is alive but I don't mind kicking it) : I completely disagree with this point. Why would being alive alone be enough for someone to respect something? why wouldnt I go around killing cockroaches and flys and bacteria and whatever else I like to. Its different if what you do will affect the balance of life in the planet (destroying forests etc etc). So I think my question about the meaning of life (what is life?) should not be taken from a moral viewpoint.

2)Why are organisms BOUND to have cells by the physical laws? I have studied biology a lot (maybe too much) and I don't see why it would be a prerequisite for life. Maybe life on earth, or in a liquid environment. But I could easily imagine replicating crystals that hold some genetic information in their structure. No cells - Alive (I would say)

3)Virii: Please don't talk about "stupid majorities" or things like that. If nobody can say what is alive or not please don't tell me that I am stupid if I say a virus is alive. I know it has to "hijack" a cell to replicate but it has quite a lot of organization, contains information for its replication and I think it has an indirect mode of replication. BUT if we can't say what is the criterion fro being alive we can't say of a virus is a live or not.

4)What does consciousness and free will have to do with life??? Someone (sorry I dont remember any names) made an argument like this: If you disconnect life from consciousness and say that bacteria are not conscious then it is like saying that people are automata and have no free will. This is a very tricky point. I don't believe in free will. People can not do anything they want seperately from their body. Try to quit heroin and you know what I mean. I believe in thought and the mind as a manifestation of our brain chemistry. I'll leave it to this as it might be too much for a day. (Maybe someone would like to explain what exactly IS this free will that people have - please no christian analysis keep it philosophical)

Quote:

---

Originally Posted by EddieSpaghetti

What about a mule? It is unable to procreate, so is a mule not alive? Same for any creature too young or too old to procreate. Are they not alive?[/b]

---

Yeayea good point, but I didn't make up those rules. Still a good point. Those rules suck. I care. Nah.

Quote:

---

What about a star? It grows and feeds and creates heavier elements that become planets when it goes nova. Is it alive?[/b]

---

I would say yes. However, it also had some other criteria that I wouldn't say a star has.

Quote:

---

My pencil is made of wood. It has cells. Is it alive?[/b]

---

My pencil doesn't have sex, does yours? How the fuck is a pencil alive? It doesn't grow, it doesn't procreate. A TREE is a live, not a pencil.

Quote:

---

If you get a flu shot, you are being injected with the dead husks of a virus to help your body build an immunity to it. They are "dead" husks which means they were formerly alive. Viruses live and die.[/b]

---

A proper biologist would tell you 'inactive' actually.

Ok lets get two things clear: -I didn't make up those rules I posted, probably I didn't even post them correctly. Secondly, I don't give a shit about any of these definitions of life. I don't even think those rules where all that. What I DO know, is that most biologist and such don't really count viruses as proper life.

Quote:

---

Bottom line: You don't know what the bottom line is. Defining what "life" is is extremely tricky.[/b]

---

No shit sherlock. : )

Still, I don't see viruses as life any more then I see a computer virus as life. A computer virus probably even has more lines of code :) But even then: WHY THE FUCK do people care? What is important is how you are going to ethically react to things uncertain of worthiness like humans and animals, like A.I. Call A.I. life, a program, intelligence, call it bananas for all I care. What matters is or people don't give a shit, or that they do.

HMKAY

Quote:

---

Originally Posted by sogart

2)Why are organisms BOUND to have cells by the physical laws? I have studied biology a lot (maybe too much) and I don't see why it would be a prerequisite for life. Maybe life on earth, or in a liquid environment. But I could easily imagine replicating crystals that hold some genetic information in their structure. No cells - Alive (I would say)[/b]

---

I think that's a valid point: we only have access to life on Earth and so far biologists are in agreement that cell-based organisms are the low threshold of what constitutes life. But what about elsewhere in the universe?

Quote:

---

3)Virii: Please don't talk about "stupid majorities" or things like that. If nobody can say what is alive or not please don't tell me that I am stupid if I say a virus is alive. I know it has to "hijack" a cell to replicate but it has quite a lot of organization, contains information for its replication and I think it has an indirect mode of replication. BUT if we can't say what is the criterion fro being alive we can't say of a virus is a live or not.[/b]

---

In my opinion, a virus is alive. Not being a biologist myself I would gladly defer to their judgement. Unfortunately, biologists are still debating it and iit is unresolved at this point. I think they are at least willing to categorize them as "semi-life", or as one biologist put it "acellular biological entities".

Quote:

---

4)What does consciousness and free will have to do with life??? Someone (sorry I dont remember any names) made an argument like this: If you disconnect life from consciousness and say that bacteria are not conscious then it is like saying that people are automata and have no free will. This is a very tricky point. I don't believe in free will. People can not do anything they want seperately from their body. Try to quit heroin and you know what I mean. I believe in thought and the mind as a manifestation of our brain chemistry. I'll leave it to this as it might be too much for a day. (Maybe someone would like to explain what exactly IS this free will that people have - please no christian analysis keep it philosophical)[/b]

---

In my opinion, the higher a consciousness evolves, the greater its free will. And "life" exists to serve as host to consciousness. Life evolves along side consciousness. I.e., an a advanced consciousness seeks an advanced life form as host. Evolution is driven by consciousness.

We were discussing this very thing in my physics class. "Why weren't you discussing this in biology?" you might ask... because I'm not taking biology--and you can't make me.

My teacher came up with a pretty interesting definition, he said:

Quote:

---

Life is the tendancy to behave improbably, and can be posessed in varying degrees.[/b]

---

At first the whole class was like... "What?" But he went on to explain. Think of a two-year-old. It is likely that that two-year-old spends much of its time bouncing off the walls in a way that can't be predicted, even by a pannel of the brightest scientists, philosophers, and other smart people. One might say that this two-year-old is "full of life".
Now imagine a person in a coma. Nobody would call them "full of life" in fact, they're behaving rather lifelessly, rather probably (I'm not sure that's the appropriate use of that word--as the opposite of improbably--what do you think?).
Think of a plant now, more probable (it will grow upward, and towards light) than, say... a dog, but behaving more improbably (the exact shape of this plant seems pretty much to be for the plant to decide) than say... a rock (which only responds to external forces, and respons in ways we can predict exactly... this was physics class after all).

One could argue that, by my teacher's definition, various sub-atomic-particles would be considered alive because they behave in ways that are so unlike your average "particle," flitting hither and thither without traveling the ground in between and whatnot, but still the locations where these particles are likely to appear are defined stastically, and rather rigidly at that.

Quote:

---

Life is the tendancy to behave improbably, and can be posessed in varying degrees.[/b]

---

That's a good idea but I see it under a different angle:

Living organisms (for me) have to contain some type of information and structure (structure is also made of information).

Structure implies local entropy has to decrease (as more information is stored in the structure of a living organism than in a random accumulation of its ingredients).

To maintain the structure (and information) the organism has to expend energy (so the entropy of its surroundings increases as the "inside entropy" stays lower)

As the probable behaviour of a natural system would be to follow increasing entropy (loss of information + structure), then I agree that life makes a local system increase its improbability.

PS: hope this makes some sense, and that I didn't murder the english language somewhere in there... haha

------------------------------------------------------------

Although this would not be enough to define a living being.