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Show ALL Forums  > Science/philosophy  > What makes something "alive?"      Home login  
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 JustDukky
Joined: 7/8/2004
Msg: 1
What makes something "alive?"Page 1 of 3    (1, 2, 3)
A very good question was asked on another thread about whether or not we will ever be able to create a living thing. (Move over Dr. Frankenstein!) Before we can ask that question, we have to have a definition of exactly what a living organism is. Once we have done that, we may find we have already created life, or that it is impossible to create (and we are therefore not "alive.")

Since there doesn't appear to be a universally accepted definition, let's discuss it and see if we can't come up with one. {I can already see this thread turning into a text-based "Jerry Springer Show" (which is what most of these threads become). Either way, it should be an interesting topic.}
 RocketMan_Len
Joined: 7/5/2006
Msg: 2
What makes something alive?
Posted: 4/13/2009 8:31:15 AM
Does that mean you don't consider bacteria or single-celled animals to be 'alive'...?

Awareness isn't necessary for something to be alive.
 Verzen
Joined: 12/9/2007
Msg: 3
What makes something alive?
Posted: 4/13/2009 9:03:32 AM
According to the biologist definition, anything that consists of Cell's is considered alive. If it has a single cell filled with organelles, then it is alive. If the being in question does not have any cells to call its own, then it is not alive. A virus is something that is not alive but has the characteristics of being alive.
It is programmed and it follows it's programming precisely.


Anything the grows... in mass or population, I would say is alive.

In your opinion a virus would be alive since it is able to grow in population, but alas, you are wrong.
 Mr.Twist
Joined: 2/11/2009
Msg: 4
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What makes something alive?
Posted: 4/13/2009 10:18:59 AM
What is life? It shouldn't be all that difficult of a question to answer.

Does it consume an outside source of energy and use it for fuel?
Does it procreate in some fashion?
Does it react to outside stimuli beyond a simple Third Law of Motion response?
Does it seek out a food source?


I'm sure there's more qualifications, but this is a rudimentary list. It leaves things vague enough that you don't have to stop at just carbon based life.
 Jiperly
Joined: 8/30/2006
Msg: 5
What makes something alive?
Posted: 4/13/2009 11:00:54 AM
I'm pretty sure the defination of life is a being that reproduces itself.
 emannigol
Joined: 2/8/2009
Msg: 6
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What makes something alive?
Posted: 4/13/2009 11:49:01 AM
I think that the most common definition is to have metabolism and an ability to procreate.
 RocketMan_Len
Joined: 7/5/2006
Msg: 7
What makes something alive?
Posted: 4/14/2009 5:43:04 AM
By a lot of definitions I've seen, *fire* would be classified as alive...

It consumes fuel to release energy...
It excretes CO2 and ash as waste products...
It can move from place to place, reproducing itself as it goes...
It's capable of dying...

Now - since fire is obviously not a living thing, I think that the definition needs some refining.
 JustDukky
Joined: 7/8/2004
Msg: 8
What makes something alive?
Posted: 4/14/2009 6:30:08 AM
I'm inclined to agree that the definition needs refining.

For instance, we seem to all agree that a living thing must be "aware" or "conscious". We have to be careful here because we've just run into two more words without a solid definition. Worse, we seem to be using them interchangeably.

Is a plant aware? I would say yes. It must be aware of the sun, or flowers wouldn't open and point in its direction, or close when the sun goes down. So a plant is clearly able to react to changes in it's environment. To do so, it must be aware of the environment on some level. A plant must "sense" changes in its environment. So how about we define awareness to be "The perception of environment"?

Is a plant conscious? Well, now we gotta define "conscious". Are you conscious when you're sleeping? No. You aren't even "aware" by the above definition. If you are unconscious, you are unaware, and also true that if you are aware that you are conscious; but are they synonymous? Well. suppose some nasty evildoer came along and severed all your sensory input and left your poor brain with no fresh information to process. Are you dead? Not yet. You can still think. Are you aware? How can you be; all sensory input has been removed. Clearly, consciousness differs from awareness. Consciousness doesn't even have to relate to the environment. Why don't we define consciousness as "abstract processing of information", better known as "thinking".

At least when we use these definitions we can still say that when we sleep and we are both unaware and unconscious and don't have to feel lower than a plant on the tree of evolution.
 Mr.Twist
Joined: 2/11/2009
Msg: 9
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What makes something alive?
Posted: 4/14/2009 8:31:41 AM
I just thought of another qualifier for life, or at least as we consider it;

Does it have DNA or RNA?

I'm pretty sure that everything we consider to be alive contains DNA, so that might be the deciding point.
 ishaun
Joined: 6/20/2008
Msg: 10
What makes something alive?
Posted: 4/14/2009 9:21:50 AM
Life can't be defined in my opinion, at least not all life in one definition.
 JustDukky
Joined: 7/8/2004
Msg: 11
What makes something alive?
Posted: 4/14/2009 3:33:05 PM

For now.(if forced).I'd go with an earlier poster's definition of a cellular based definition...


I'd tend to agree that all life (as we generally think of it) seems to be cellular in nature. However, we also consider single cells (like bacteria) as living organisms. Adding more cells only makes more complex living organisms; so is it safe to say (at this point) that a "cell" might be the smallest unit we could consider to be alive (at least the smallest unit we are currently aware of that we seem to universally agree is alive)?

Now I'm not conceding that a "cell" necessarily has to be what we usually think of as a cell (carbon based, consumes, excretes, etc.), but for the moment at least we can look at biological cells. When we get to virus level, we seem to be running into some confusion over whether or not a virus is alive, but that's OK; we really don't know because we don't have a proper sense of all that goes into being alive. Hopefully, this thread will eventually lead to some satisfactory answers we can all accept. But I digress...

If we can all agree that a cell is alive, we can look at the properties of a cell and its components, compare them to a virus's properties & components and see just where some here are making the distinction between living & non-living structures. We may eventually all agree that viruses are alive (or non-living) and thus have a better definition of what constitutes life. If we agree that a virus is alive, we'll have to keep digging; if we agree it isn't, it will be because we have agreed on the definition that this thread is asking for.

So where do viruses & cells differ?
 Beaugrand®™©
Joined: 3/24/2008
Msg: 12
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What makes something alive?
Posted: 4/14/2009 4:52:32 PM
As I recall from high school biology, living things have the ability to breathe, ingest nutrients, reproduce, and respond to stimuli.
Anaerobic bacteria seem not to need to breathe, viruses and prions seem not to be able to reproduce on their own- but these, I think, must be exceptions. I think of a virus using a living cell to reproduce as the same as my going to a butcher shop to buy meat- I lack the tools and the skill to butcher my own meat, does this mean I can't eat it? Does that disqualify me as a carnivore? I think not, therefore I accept viruses, and prions, as "parasitic forms of life."

But since they reject the stimulus, I'm not so sure about Republicans. I'll have to poll the viruses to see if they are willing to grant them the same conditional status as "parasitic life forms."
 Possibilities~
Joined: 3/23/2009
Msg: 13
What makes something alive?
Posted: 4/14/2009 6:46:27 PM
A marvelous question, JustDukky. One I've discussed / argued about many times over the years ~ fruitlessly, alas. No answers or guesses at the moment...
However, regarding the cellular idea...once a creature is dead...it still has cells. This is what you'd call a half-baked idea -- not thought out yet, (On my part) , but I feel like there is something wrong with it... Should probably have waited to post...
 Mr.Twist
Joined: 2/11/2009
Msg: 14
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What makes something alive?
Posted: 4/16/2009 6:20:24 PM

The definition of life ussed by every science, worldwide, is "If it has a single cell filled with organelles, then it is alive. If the being in question does not have any cells to call its own, then it is not alive."

All of these other definitions can include such things as fire, prions, stars, ect, this is simply not rational.


Just to be clear. In science, something is considered to be alive if it meats these criteria:
It consits of one or more cells.
The cells contain all the processes essential for replication. (ie. the various organels)
It comsumes mater to maintain its functions and reproduce itself.


Actually, there's no universally accepted strict definition for life. There's a general consensus, which includes the requirements you listed, but it's not set in stone.
 JustDukky
Joined: 7/8/2004
Msg: 15
What makes something alive?
Posted: 4/17/2009 11:09:42 AM

It consits of one or more cells.
The cells contain all the processes essential for replication. (ie. the various organels)
It comsumes mater to maintain its functions and reproduce itself.


Replication of the cells, or reproduction of the organism?
If the former, fine, but if the latter, then (for instance) a mule isn't "alive."

I'm well aware of the scientific definitions, but you must be aware that those definitions were intended to define life as we know it, to set a standard that clearly defined biological life. What happens if we ever encounter a conscious, thinking, gaseous entity for instance? Do we simply say outright that it isn't alive because it doesn't meet our defining criteria? If I were an intelligent gaseous creature (assuming for the moment such things can exist), would I be a little insulted that those stupid bipedal solids didn't consider me alive, or would I simply not consider humans alive because they didn't meet MY criteria for a life-form?

I started this thread not to confirm or deny the scientific/biological definitions, but to illustrate how arbitrary & limited they are. You can't extrapolate a definition based on the study of existing organisms to unfamiliar life-forms. The best science can do so far is take an extremely parochial stance on what it calls life. That's good for research (as far as it goes in biology), but not for a real understanding of what most would consider a REAL definition of "living thing."
 desertrhino
Joined: 11/30/2007
Msg: 16
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What makes something alive?
Posted: 4/19/2009 8:01:04 AM
Nothing is alive unless it can die.


...if you've answered yes or you've answered no, you've lost your own buddha-nature.


How can you lose that which is not?
 VVendy
Joined: 6/7/2008
Msg: 17
What makes something alive?
Posted: 4/19/2009 2:41:14 PM

we have to have a definition of exactly what a living organism is

living generally is something that consumes energy transforms it to matter or usable energy and excretes. lately people have tried adding thinks and procreates to the list but mules are alive and they can't procreate and no one has registered thought in single cell organisms.
 DaManley
Joined: 2/11/2009
Msg: 18
What makes something alive?
Posted: 4/19/2009 6:07:57 PM
Well I don't really feel like thinking too hard about this.
But. I have always enjoyed the thought that FIRE could be considered alive.
:D
 Vancer
Joined: 10/29/2006
Msg: 19
What makes something alive?
Posted: 4/20/2009 8:44:04 PM
I think the question was already answered on a Star Trek episode.
It only took 40 minutes to answer to!
Plus there was lots of machine on Kirk romancing.
And if there wasn't, then there should have been.
 VVendy
Joined: 6/7/2008
Msg: 20
What makes something alive?
Posted: 4/21/2009 8:04:27 AM


1) Be able to reproduce
2) Regulate itself
3) create energy to use


I differ from you in each in opinion but if we were defining sensuous of conscious life I would agree. A lot of life forms do not show any regulation of reproduction, self or how they use energy.
 Mr.Twist
Joined: 2/11/2009
Msg: 21
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What makes something alive?
Posted: 4/21/2009 10:03:40 AM

Bright1Raziel,

No need to deride the uneducated with "thick" and "take a biology class people."


No need to be insulting.
 x_file
Joined: 6/25/2006
Msg: 22
What makes something alive?
Posted: 4/21/2009 3:37:22 PM


What makes something alive?


I do! And no, I don't mean it as a joke. I mean, I am the thing that makes itself alive - and no I'm not talking about my body - I mean the real me - call it a soul if it's easier.
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