Talk:Life
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Definition
The "exceptions" to the definition (besides the mule) are untrue. As mentioned below fire is clearly not alive for obvious reasons, and viruses are not considered to be living organisms. Viruses simply react to chemicals and eject their DNA automatically, making them more similar to machines like pumps or cars.
meh, somebody already said all of this...
I deleted this statement:
- fire is alive. (This could be remedied by adding the requirement of locality, where there is an obvious feature that delineates the spatial extension of the living being, such as a cell membrane.)
I removed the above statement from the article because it is not true as the definition stands. Fire does not have any metabolism or response to stimuli. AdamRetchless
- [Peak:] By removing "fire", you are doing a disservice to the integrity of the basic ideas of the original author. The main point is that the old-fashioned approach (based on a clever but ultimately haphazard collection of criteria) does not work very well. Fire responds to stimuli (e.g. wind), and it has "metabolism" in the sense identified ("consuming, transforming and storing energy/mass; ..."). Of course, one can define "metabolism" in a sophisticated way, but this section is about *unsophisticated* approaches. Please reconsider.
- Thanks. Peak 06:57, 30 Mar 2004 (UTC)
- Boy, am I out of touch with the common man? ;^) I can see your point. However, it doesn't take a biologist to realize that fire is not alive, so perhaps our "conventional" definition is lacking. For one, I think the common-sense definition includes the fact that living beings include a solid structure, whereas fire does not (it is gas, or maybe plasma). As for metabolism, fire obviously consumes fuel, but it doesn't produce any structures that further the "life" of the fire. Likewise, fire may change as a consequence of external factors, but it doesn't change in ways that promote its continuation. I don't think a person needs a degree in biology to understand these ideas, but perhaps they still fall in the "sophisticated" camp.
- Anyway, I think that the real point should be that a list of traits is not a definition. The listed "exceptions" are relevant for those who are trying to make a comprehensive definition of life; several other phenomena are similar to life, and any definition needs to be sure to distinguish between these phenomena. BTW, crystalization also falls in this category of things that share some traits with life, but are not life. AdamRetchless 14:08, 30 Mar 2004 (UTC)
Otherwise, I intend to remove this...
- Motion, either moving itself, or having internal motion
...from the definition if no-one objects. Anything that is growing, reproducing, and responding to stimuli is is necessarily moving. AdamRetchless 02:53, 30 Mar 2004 (UTC)
My definition: Life is a special kind of organization, of information. It uses self-reproduction as its main tool to stabilize and improve itself. In its profane meaning it forms structures out of dead mass, but in its meta sense and also since the invention of the "electronic brain" we extend the term of "life" to massless systems, too. Grasso
Assuming we get arount to designing a machine that is somehow able to make a copy of itself, allowing for imperfections, would we consider it to be alive? --Seb P.S. I think there's going to be quite some action in this area...
- Oh yes, there will be...
- As to the question, since molecular biology effectively reduced cells to machines, I think we should not become carbon-chauvinists over the idea of self-replicating machines. Mentioning that, we should probably mention this "Life simulation" (you know the one, you can look at it for hours building patterns;). --Magnus Manske
- Think it would be reasonable for me to insert a link to nanotechnology and clanking replicator? I consider those to be alive (well, nanotech isn't by _definition_ a self-replicating system, but it's usually assumed as such), but I wouldn't want to go too far out on the fringe before the more conventional parts of life's article get filled in first :) -BD
- Read molecular assembler, and stop using the term "nanotechnology", it's worthless (means nothing). Molecular engineering is a better term, the Technological Singularity when invoked can be called by just that name.
I know reproduction is usually at the forefront in textbooks, but mules are definitely alive in my book, and some comment on that short-coming might be made. On the original wiki (http://www.c2.com/cgi/wiki?DefinitionOfLife) we settled on homeostasis the most likely defining characteristic, since it doesn't have any real counter-examples, but is somewhat vague. (The definition's been made much more rigorous since then.)
No mention of reverse entropy?
Viruses
Hmm, the mule is already a shocking example, but how about an infertile person? Is that person not alive? And if he/she's not dead either, should we call the person undead? *g
To me, life are cell-based organisms that have a metabolism. So I'm not a carbon chauvinist, though maybe a cell chauvinist. And I'm not talking about memory cells holding a computer program. Neither am I intending to call jails alive! Ok, this seems more complicated now. Maybe we should just start an alphabetical list...
But now for something actually useful: A virus is said to be not alive because it doesn't grow. Does it not also fail to have metabolism or internal motion, and isn't it also unable to reproduce on its own? The latter (autonomous reproduction) was pointed out to my class in school, but now I think this would be a slippery slope - neither can, for example, wasps that lay their eggs into live caterpillars, reproduce on their own.
Prions
Definitely not alive. Just malformed parts of life.
5 attributes
Are there any biologists or other scientists who seriously consider mules dead and fire alive? It sounds like whoever slapped this hodgepodge of ideas together is simply trying to make a sardonic point: that the 5 attributes can't be strictly and mindlessly applied.
Fire isn't a form of "life" - it's inorganic. Mules are alive, even though they're all sterile. A man who gets a vasectomy or a bull that gets castrated, is still alive.
Come on, let's make this a serious article.
- I am unsatisfied with the list of five attributes. First, I would like to know what justification there is for saying "an entity has traditionally been considered to be alive if it exhibits all the following phenomena at least once during its existence..." and then listing those five traits. Who first listed these traits? Even if we can't confidently find the "the first" use of this list, at least we could find some sort of authoratative source (a textbook perhaps) that uses this particular list. If this is the first time that this list has been collected as such, then the current structure is misleading and will need some major editing. In that case, the list should be changed such that it is clear that this list is NOT the traditional list of essential traits; instead, we should write that that the nature of life is often discussed in terms of posession of essential characteristics, such as those in the list. The special cases (mule, virus, fire, crystal) should be used to point out the difficulty of using any one of these traits as the defining trait. Then we can go on to point out that a list of characteristics is not a clear and coherent definition of life, then move on to present assorted attempts to provide a coherent definition of life. AdamRetchless 13:41, 4 Apr 2004 (UTC)
Anyway, I came here today because I'm looking for someplace to put the idea about when human "life" begins - as relates to abortion and abortion in the United States. There's a controversy between those who say abortion is always (or sometimes) murder, because it's killing a "living" human "baby" - and those who say it's sometimes (or always) not murder, on the specific grounds that whatever attributes the fetus might have, being "human" is not one of them (or something like that, maybe a pro-choicer can explain it better).
I think we need a sidebar discussion on what constitutes "human life" both legally and scientifically (they might not be the same in all jurisdicitons) - as background for the articles on abortion. If the US bans partial-birth abortion, our readers might have a renewed interest in a neutral discussion of the science, law, and ethics of the issue. --Uncle Ed 15:10, 22 Oct 2003 (UTC)
- The definition of life is irrelevant to abortion. Of course a foetus is alive. That's not what's at issue. The issue is whether or not it's OK to kill it. And I say this as a "pro-choicer". Evercat 15:20, 22 Oct 2003 (UTC)
- Good point, 'cat. Maybe "pro-lifers" have the wrong code name, then. Anyway, it might be around the meaning of what it is to be "human" that the question hinges. I have no POV whatever on the subject, despite what Erik has said elsewhere. My church says simply that we should avoid abortion -- not that it's a sin. We have much more interesting issues: like brainwashing, deprogramming, what is a cult and are we one?, the meaning of faith, the question of life after death, and oh yes, the identity of the Messiah -- then there's all the controversial issues I haven't even listed! --Uncle Ed 20:20, 22 Oct 2003 (UTC)
- Even as a "pro-choicer" I would say that a foetus is a human life. The interesting question in my opinion is whether that makes it a person. That's a very seperate discussion, and I would hope this debate would really be discussed on abortion or related pages. I don't like the idea of life or person containing anything more than a passing reference to the abortion debate. :-) Evercat 15:34, 23 Oct 2003 (UTC)
That sounds good to me. The clean up of the life article has no real bearing on the abortion controversy. The fetus isn't dead; that's not the issue; I think we agree there. The fetus isn't even "non-human biological tissue" which suddenly "becomes human" like a Frankenstein monster created from frog's legs and an ape's body.
I'll try to make this my last post at talk:life and you or MyRedDice or someone can move and/or refactor to the appropriate talk page.
But, perhaps the ethical/legal issue has to do with "when human life begins" in the sense of "when does the fetus transform legally, morally and ethically" from a "freely killable life-form" (like a rat or a pig) into a "being with human rights" who may not be deprived of life except by due process or something like that.
Anyway, it's a good thing you and I are able to talk about this without arguing: unlike "E" and "J" (wink wink) -- not that I'm naming anyone... --Uncle Ed 21:14, 23 Oct 2003 (UTC)
Definition
Someone changed the definition from "An entity is" to "An entity or organism is", but adding organism here introduces a circularity of definition, since an organism is alive.Peak 05:55, 25 Dec 2003 (UTC)
Moved from article
This comment was moved from the article, because first, it was really phrased more as comment than actual content and hence should really be here on the Talk page, and second, as this is not really the focus of the article, these debates are already covered in other articles such as abortion etc. --Lexor|Talk 08:17, 14 May 2004 (UTC)
- to the second definition above, there is contention as to whether life starts at birth or at the point of fertilization.
Extraterrestrial life
It says in this article that as of 2004 earth is the only place known to have human life. Well, 2004 has been over for only 2 weeks, and has there been any recent news during the past 2 weeks?? Georgia guy 01:11, 16 Jan 2005 (UTC)
Life is not what we once thought it to be - New understanding
Bad news for the living.
(1) Your not really alive.
(2) It turns out your just a Bio-molecular machine: Bio(carbon based)- Molecular(atomic level construction)- Technological Machine(No soul, maybe not even spirit).
(3) Synthetic biology is up and running. That's man's ability to CREATE LIVING MACHINES. Living systems. Synthetic life as it were.
(4) You are so well made, you could of never guessed this to be true. For you look alive. Feel alive. Even Think and Talk as to being alive.
What is alive. We do not know yet. Every thing we look at is an intelligently design system of molecular devices that create a whole we call creature.
Scientist's are now using bacterium for their ability to create at the molecular level. If we feed it a new DNA software programming. It will create it for us. This is an old trick the virus does. Now we can do it. It's cheaper and easier. Billion dollar factories may no longer be needed. We can now just Grow it together.
References are always coming:
http://groups.msn.com/EvolutionBloopersVSGodCreates/general.msnw?action=get_threads
Do some web searches: Synthetic Biology, DNA computers, System biology, computational molecular biology, Biological computing, Biocomputers, Biological Computer Diagnoses Cancer(New) Biological energy conversion, Cellular computer models.
By: --Bio-molecular-Tony 23:36, 30 Apr 2005 (UTC) Jan 29,2005 Bio-molecular-Tony
(It's the 21 Century- wakee, wakee)
Have you had you daily genetically modified food today....
Daniel 03:16, 26 Mar 2005 (UTC)
Are you saying that anything alive isn't alive? What does being a Bio-molecular machine have to do with having a soul? Normally I'd say whatever we define as alive is alive, but after seeing this page I'd have to say that few know what they consider is alive, and thus we don't know what life is.
I figure a virus is alive. it starts out unable to reproduce, but it then eats a cell, grows considerably, and gains the ability to reproduce. Fire is not alive as it is not an entity, but an event. More specifically it is the event of live ash reproducing. There are only two actual attributes something must have in order to be alive. It has to move and grow in order to reproduce, and, according to the second law of thermodynamics, it has to have energy applied to do anything useful, thus leaving only reproduction and response to stimuli. I might be able to rule out that last one too if I find out exeactly what it means. I belive anything, including life and art, can be defined, even if every brain cell of every person who ever existed must be thuroughly incorperated into the definition to do it. Daniel 03:16, 26 Mar 2005 (UTC)
Get a life.
Molecular machine
Life is but a Molecular machine. Every plant, every animal, and yes every human. All that you see. All that is said to be alive. Is made of the greatest Molecular machines known to man. So called nature is but a forest of machinery on the molecular level.
When you "eat" food. Are you not getting new molecular parts for you own machinery. You can not eat dirt. So you must get it from those (Plants) that can.
Reference searches:
Synthetic Biology
System Biology
Biology- energy conversion
ENTROPY AND HEAT DEATH
DNA programmed molecules
http://groups.msn.com/EvolutionBloopersVSGodCreates/general.msnw?action=get_threads&all_topics=0
http://www.worldpress.org/article_model.cfm?article_id=2153&dont=yes
Biomolecular computing is an interdisciplinary field of science which views biological systems like a PC....
--Bio-molecular-Tony 08:57, 19 Apr 2005 (UTC)
A new definition
I heard a scientist define life as "a property of the DNA molecule". Is there space for that definition here? --JiFish 11:25, 23 May 2005 (UTC)
Maybe the working programming would be closer to the truth here.
http://www.sooty.ca/gene-hacking.html "Of course the programming language is DNA and its machine code runs all life on this planet."
http://www.weizmann-usa.org/site/News2?JServSessionIdr001=tdxgmh93y1.app13b&page=NewsArticle&id=5077
'The living cell contains incredible molecular machines that manipulate information-encoding molecules such as DNA and RNA in ways that are fundamentally very similar to computation,'
http://pard.technion.ac.il/archives/presseng/Html/PR_udicomuterEng_27_2.Html
'all biological systems, and even entire living organisms, are such computers.'
'Every one of us is a bio-molecular computer, that is, a machine in which all four components are molecules “talking” to one another in a logical manner.'
--Bio-molecular-Tony 01:30, 23 Jun 2005 (UTC)