What constitutes life?

[Thanatos]

Anything that self-replicates and that has heritable characteristics. Biology textbooks say it must also have cells, the capacity to grow, and a chemical metabolism but IMHO that's stupid because it places too much importance on the physical process.

Alternatively, if it evolves then it's alive.

[Senor Hoint]

I would say the fundamental characteristic of life is the ability to self-replicate.

As technology advances I'm sure that the line between what is "living" and what "nonliving" will become less and less self-evident.

[Medensis]

Thanks for the quote. I guess it just goes to show that no thought is truly original. I'm not familiar with The Watchmen but I may have to check it out. Is it a book or...?

My top favorite movie. Very philosophical. Check it.

[Jack]

Anything that self-replicates and that has heritable characteristics.

I would say the fundamental characteristic of life is the ability to self-replicate.

Could those characteristics simply be abilities of cells and atoms working in concert? In other words, the result of particular chemical interactions between primarily carbon, hydrogen and oxygen atoms is a state we refer to as life. Life then would be a designation we assign to specific atomic interactions or combinations while non-living is the designation we give to other interactions or combinations.

[Senor Hoint]

Could those characteristics simply be abilities of cells and atoms working in concert? In other words, the result of particular chemical interactions between primarily carbon, hydrogen and oxygen atoms is a state we refer to as life. Life then would be a designation we assign to specific atomic interactions or combinations while non-living is the designation we give to other interactions or combinations.

Well, yes. Obviously the atoms themselves aren't living. It's the arrangement of and interactions between the atoms that defines whether they are alive or not. Certain types of chemical reactions, those that facilitate self-replication (since, though we tend to forget it, all the various characteristics and lifeways of different organisms are just a pathway that DNA takes to replicate itself more efficiently) are considered life, and others are not.

[finder]

I must of misunderstood. I thought opinions on what is life were being sought. I didn't know text book definitions were. My bad.

[gallo]

I must of [sic] misunderstood.

Do you mean you must have misunderstood?

I thought opinions on what is life were being sought.

That's true. But your opinion is being criticized because it is too narrow. Your definition eliminates 99% of the living world. By your lights, trees aren't living. Are you sure you want to make that claim?

I didn't know text book definitions were. My bad.

That's silly. It is you're bad to ignore more than 99% of life in your definition of life. It has nothing to do with any sort of text book. Trees are alive. Worms are alive. Fungi are alive. Mosses are alive. Algae are alive. Bacteria are alive. But none of them meet your definition of life. How narrow minded of you.

[gallo]

I didn't mean to kill the thread. Maybe I can bring it back.

I decided to start a thread based on the end of this thread (http://www.volconvo.com/forums/showt...119#post884119)

So, let's hear it: what do you think constitutes life? Do viruses? What about red blood cells (which have no nuclei) or neurons (which are incapable of cellular division)?

Viruses? No. They don't have a cellular organization. They are strands (single and double) of both RNA and DNA. They have no metabolism, they don't grow, and they do not respond to stimuli. More importantly, they do not reproduce, the replicate by using the mechanisms of the cells that they invade.

Red blood cells: No. They are part of living organisms that are produced by living organisms.

Neurons: No. Same reason. What you are asking is the equivalent to asking if the little toe on the left foot of a human is alive. Cut it off and find out if it alive separated from the human.

[seyorni]

I suspect it's more a continuum than a black or white dichotomy.
Self replication won't do it. There are non-organic molecules that can replicate.
Viruses are all out. They can't even self-replicate. They're no more alive than a computer virus.

[gallo]

I suspect it's more a continuum than a black or white dichotomy.

Indeed. The definition gets fuzzy at times.

Self replication won't do it. There are non-organic molecules that can replicate.

But they don't have anything that can be called a metabolism. Self replication is but one requirement in the definition of life.

Viruses are all out. They can't even self-replicate. They're no more alive than a computer virus.

Except that they are actual rather than virtual.

[Jack]

Obviously the atoms themselves aren't living. It's the arrangement of and interactions between the atoms that defines whether they are alive or not.

So then life is nothing more than a word we use to describe certain combinations of atoms that produce certain results (e.g. reproduction, sustainability, etc.). Life arises from the non-living, it's the result of non-living atoms acting in concert to produce an effect we call life.

I suspect it's more a continuum than a black or white dichotomy.

I agree. At some point along the line of atoms in certain combinations their effects pass from non-living to life.

[Choose Life]

But the ant? When observed objectively their is no evidence of subjective experiences for the ant. We see an over all purpose of serving the ecological system for which it inhabits and nothing more.

Absence of evidence is not evidence of absence.

No proof they have their own experience, but no proof they don't.

So it's possible.. Although it wouldn't be what you and I think of with our own consciousness. It would be a more basic experience, without reasoning or remembering or even decision making necessarily.

I think they do have an extremely basic and limited form of consiousness. That's not a fact but my speculation.

Ants don't do much, but that which they do, they do all the time.

As an example.. Imagine you had a job to do.. That job being something simple and mundane.. Like pushing a button every time it lights up.. All you're doing is pushing a button and nothing else to otherwise engage you or even require much attention.

If you do for hours on end, and are getting really bored, it's possible that such repitition detatches you from the brain as you don't really need your brain much as you're simply doing it on a reflex. When that happens, you might go into a trance like state.. You're not really thinking about anything at all. The mind goes blank. You respond to the world around you but only if something different happens like a danger. Suddenly you will begin thinking again, consciously deciding what to do about this new environmental stimulus. Even for you, it may not be a concsious choice but more instinct.. Like suddenly pieces fall from the ceiling that's caving in and you put your arms over your head as a reflex. You noticed it, but you didn't put much thought into your reaction. Similar to zoning out while you are driving down the motorway for a long time. But a small tiny part of your consciousness is paying attention to the state of that button and whether or not it needs to be pushed. You do the task with little thought. But on a small level, you're technically still aware. At least aware about the task at hand, but not thinking about it.

To put it another way.. Maybe they are aware, but they are not aware that they are aware.