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Author Topic:   What is Life?
Panda
Member (Idle past 1877 days)
Posts: 2688
From: UK
Joined: 10-04-2010


Message 31 of 268 (587200)
10-17-2010 4:16 PM
Reply to: Message 29 by mosassam
10-17-2010 3:16 PM


mosassam writes:

I wondered if there was a similar kind of definition for Life but, judging by the responses I've received to this thread it appears there isn't. This leads me to suspect that Life, like Mind, cannot be scientifically proven to exist.


Just because we don't have a definition, does not mean that it does not exist.

Does happiness exist? Yes?
Well, there is no exact definition of happiness.

Not having an exact definition does NOT mean that it doesn't exist.


This message is a reply to:
 Message 29 by mosassam, posted 10-17-2010 3:16 PM mosassam has responded

Replies to this message:
 Message 33 by mosassam, posted 10-17-2010 4:37 PM Panda has responded

  
mosassam
Junior Member (Idle past 3075 days)
Posts: 15
Joined: 02-26-2009


Message 32 of 268 (587202)
10-17-2010 4:21 PM
Reply to: Message 30 by Larni
10-17-2010 3:47 PM


Re: Clumsy label
'Life' is indeed a clumsy label but I am trying to reach some kind of mutual understanding about this label as it seems very nebulous at the moment. If we were to take as an example a rock and a tree we could say with some kind of certainty that one is living and one is not. One has Life one does not.
Would you say that the Life in the tree is an emergent property of incredibly complex electro-chemical processes? If so, would you agree that this implies that Life is a by-product of this complexity?

PS thanks for writing something constructive as I am genuinely trying explore the intuitive feeling I have that, far from being a by-product, Life is, in some as yet unspecified way, the 'driving force' behind this complexity and not the other way round.


This message is a reply to:
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Replies to this message:
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mosassam
Junior Member (Idle past 3075 days)
Posts: 15
Joined: 02-26-2009


Message 33 of 268 (587205)
10-17-2010 4:37 PM
Reply to: Message 31 by Panda
10-17-2010 4:16 PM


In response to PANDA.
This is precisely the kind of semantic nonsense I will be refusing to engage with in the future. I see you have chosen to omit the phrase 'scientifically proven'.
Does happiness exist? Yes
Is it scientifically proven to exist? NO
Now think about this for a second - it exists but it is not scientifically proven to exist.
Have the manners not to wade in with some facile comment, actually think about it because there is a paradox here that is at the heart of what I'm trying to understand.
This message is a reply to:
 Message 31 by Panda, posted 10-17-2010 4:16 PM Panda has responded

Replies to this message:
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Larni
Member
Posts: 3976
From: Liverpool
Joined: 09-16-2005


Message 34 of 268 (587207)
10-17-2010 4:51 PM
Reply to: Message 32 by mosassam
10-17-2010 4:21 PM


Re: Clumsy label
If so, would you agree that this implies that Life is a by-product of this complexity?

I would say that when you get enough connected physical reactions going on in one place it gets labelled as life.

I don't agree that 'life'is an entity as such rather than a construct: another way to think of it is to think of it is like how you would think of the word 'big': it's a vague category.

When does 'big' become 'small'? Same thing with 'life' and 'non-life': 'big' and 'non-big'.

Is 'big'a by-product or just a convenient label? Same thing with the word 'life'.

Does happiness exist? Yes
Is it scientifically proven to exist? NO

Just a small but important point. Science cannot and does not ordinarily 'prove' things. Evidence is used to support a hypothesis.

Edited by Larni, : Second point


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Panda
Member (Idle past 1877 days)
Posts: 2688
From: UK
Joined: 10-04-2010


Message 35 of 268 (587209)
10-17-2010 5:07 PM
Reply to: Message 33 by mosassam
10-17-2010 4:37 PM


In response to mosASSam.
mosassam writes:

Have the manners not to wade in with some facile comment, actually think about it because there is a paradox here that is at the heart of what I'm trying to understand.


Ok, since you accuse me of lacking manners, I will act without manners.

mosassam writes:

it exists but it is not scientifically proven to exist.


This is not a paradox - it is simply that you are stupid.

Edited by Panda, : No reason given.

Edited by Panda, : No reason given.


This message is a reply to:
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Parasomnium
Member (Idle past 860 days)
Posts: 2191
Joined: 07-15-2003


Message 36 of 268 (587210)
10-17-2010 5:16 PM
Reply to: Message 30 by Larni
10-17-2010 3:47 PM


Re: Clumsy label
Larni writes:

A human being has many chemical and electro-chemical processes taking place in her body but these are the same processes that take place in a virus [...]

That's not quite true: hardly any processes take place in a virus itself. One of the characteristics of viruses is that they have outsourced almost all of their chemistry to their host cells. All a virus does is insert its DNA into a host cell. The cell then takes care of the rest.

I believe Richard Dawkins said somewhere that life is molecular information technology, and I think he was pretty much on the mark there. Viruses have managed to strip this concept to the absolute bare minimum: molecular information in an envelope able to make sure the information is copied. Other lifeforms have gone to sometimes extraordinary lengths to get the job done, by building enormously complex aggregates of billions and billions of cells, some of which we call elephants, others we call sequoias. But in the end these big bodies serve the same purpose as the simple protein envelopes of viruses: to make sure the DNA inside it gets copied.


"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.
This message is a reply to:
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Straggler
Member
Posts: 10285
From: London England
Joined: 09-30-2006


Message 37 of 268 (587214)
10-17-2010 5:59 PM
Reply to: Message 36 by Parasomnium
10-17-2010 5:16 PM


Re: Clumsy label
Are viruses a form of life according to biologists or not?

I have never been very clear on this.

And I understand that the discovery of "large" viuses has confused the issue by suggesting a genetic history that may mean what we call viruses were not always so parasitic and may warrant their own branch on the evolutionary tree.

Or something like that.......

Sorry for my vagueness. I am looking for info from those that know rather than a debate about a topic I am wholly ignorant in.


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Blue Jay
Member (Idle past 862 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 38 of 268 (587235)
10-17-2010 9:36 PM
Reply to: Message 33 by mosassam
10-17-2010 4:37 PM


Hi, Mosassam.

Welcome to EvC!

I think the point everyone is trying to get across to you is that defining "life" really is only a semantic issue, and nothing more.

Generally, biologists define "life" with an arbitrary set of criteria that are usually formulated such that the set of things the particular biologist wants to consider "life" get included, while everything else gets excluded. Later biologists may latch on to these definitions and defend them dogmatically, but thats neither here nor there as far as Im considered.

We currently have no evidence for the existence of a sort of essence or property that distinguishes what we call "life" from what we don't call "life." Currently, we can only describe life based on a few superficial characteristics like self-replication or growth, none of which has been found to be unique to whatever group of things we define as life.

So, it seems that life is just the co-occurrence of multiple distinct factors that can be found in isolation or in partial combinations outside of what we commonly call life. This does not seem to offer much opportunity for life to be a distinct property or essence.

But, this is just more semantic nonsense, I suppose.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
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Blue Jay
Member (Idle past 862 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 39 of 268 (587239)
10-17-2010 10:25 PM
Reply to: Message 37 by Straggler
10-17-2010 5:59 PM


Re: Clumsy label
Hi, Straggler.

Straggler writes:

Are viruses a form of life according to biologists or not?

I have never been very clear on this.

If you are ever very clear on this, I would take it as evidence that you are out of touch with reality.

But, since the people who study viruses are generally thought of as biologists, and since the study of viruses is parallel to the study of "real" living things in virtually every way, I think you're safe categorizing biologists as de facto proponents of viruses as life-forms, although they may or may not formally argue one way or the other until they're blue in the face.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
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Damouse
Member (Idle past 3069 days)
Posts: 215
From: Brookfield, Wisconsin
Joined: 12-18-2005


Message 40 of 268 (587476)
10-19-2010 1:38 AM
Reply to: Message 32 by mosassam
10-17-2010 4:21 PM


Re: Clumsy label
quote:
'Life' is indeed a clumsy label but I am trying to reach some kind of mutual understanding about this label as it seems very nebulous at the moment. If we were to take as an example a rock and a tree we could say with some kind of certainty that one is living and one is not. One has Life one does not.
Would you say that the Life in the tree is an emergent property of incredibly complex electro-chemical processes? If so, would you agree that this implies that Life is a by-product of this complexity?

One "has" life? Kind of a silly way to put it.

Semantic response: You seem to refer to life as an physical entity, much like matter and energy. I would strongly disagree with you on this. Life is a pattern, not an object. When a man loves a woman (music), there is no place you can look to see their relationship. The word relationship describes something about them.

Life is a description of those complex processes, not a product.

Realistic response: Jar's point is obvious and valid, but his picture will also show my point. There's plenty of fuzziness around the green areas, be we can surely exclude the colors that ARENT green. You may not find the solid line that distinguishes green and not green, but you can narrow it down a very appreciable amount.

It would help if you gave some sort of context.


This message is a reply to:
 Message 32 by mosassam, posted 10-17-2010 4:21 PM mosassam has not yet responded

    
Parasomnium
Member (Idle past 860 days)
Posts: 2191
Joined: 07-15-2003


(1)
Message 41 of 268 (587606)
10-19-2010 6:20 PM
Reply to: Message 32 by mosassam
10-17-2010 4:21 PM


Re: Clumsy label
mosassam writes:

I am genuinely trying explore the intuitive feeling I have that, far from being a by-product, Life is, in some as yet unspecified way, the 'driving force' behind [...] complexity and not the other way round.

Ever since Darwin we know quite well what the driving force behind the increasing complexity of life on earth is: it's Darwinian evolution. This suggests another interesting way of defining life, for which I'll quote Gerald Joyce (look under the heading "Proposed", a bit further down):

"Life is a self-sustained chemical system capable of undergoing Darwinian evolution."

Whether one could take this one step further and include any such system, not just chemical ones, is a matter of debate. Speaking for myself, I would be inclined to view a computer simulation in the form of a genetic algorithm as genuine evolution, but I would not go so far as to call it life.


"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.
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Jon
Inactive Member


Message 42 of 268 (587644)
10-19-2010 9:55 PM
Reply to: Message 1 by mosassam
09-02-2010 10:00 PM


Been There; Done That
At least one thread was already started, long ago, to deal with this same topic:

Definition of Life

Perhaps a review of that one would prevent the repetition of points already made?

Jon


Check out the Purple Quill!
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AlphaOmegakid
Member (Idle past 1040 days)
Posts: 564
From: The city of God
Joined: 06-25-2008


Message 43 of 268 (592905)
11-22-2010 6:34 PM
Reply to: Message 1 by mosassam
09-02-2010 10:00 PM


Sad Sad Sad
This thread is a sad commentary of the intellect of those in this forum. Three pages of semantic garbage and not one attempt at a scientific definition. Well that's not science it is religious equivocation.

Yes science defines life. There are definitions in every science textbook printed. Biology is the study of life and life is definable.

Here is probably the best definition I've seen. It is from a peer reviewed article on this subject and is fairly recent.

The first pillar of life is a Program. By program I mean an organized plan that describes both the ingredients themselves and the kinetics of the interactions among ingredients as the living system persists through time. For the living systems we observe on Earth, this program is implemented by the DNA that encodes the genes of Earth's organisms and that is replicated from generation to generation, with small changes but always with the overall plan intact. The genes in turn encode for chemicalsthe proteins, nucleic acids, etc.that carry out the reactions in living systems. It is in the DNA that the program is summarized and maintained for life on Earth.

The second pillar of life is IMPROVISATION. Because a living system will inevitably be a small fraction of the larger universe in which it lives, it will not be able to control all the changes and vicissitudes of its environment, so it must have some way to change its program. If, for example, a warm period changes to an ice age so that the program is less effective, the system will need to change its program to survive. In our current living systems, such changes can be achieved by a process of mutation plus selection that allows programs to be optimized for new environmental challenges that are to be faced.

The third of the pillars of life is COMPARTMENTALIZATION. All the organisms that we consider living are confined to a limited volume, surrounded by a surface that we call a membrane or skin that keeps the ingredients in a defined volume and keeps deleterious chemicalstoxic or dilutingon the outside. Moreover, as organisms become large, they are divided into smaller compartments, which we call cells (or organs, that is, groups of cells), in order to centralize and specialize certain functions within the larger organism. The reason for compartmentalization is that life depends on the reaction kinetics of its ingredients, the substrates and catalysts (enzymes) of the living system. Those kinetics depend on the concentrations of the ingredients. Simple dilution of the contents of a cell kills it because of the decrease in concentration of the contents, even though all the chemicals remain as active as before dilution. So a container is essential to maintain the concentrations and arrangement of the interior of the living organism and to provide protection from the outside.

The fourth pillar of life is ENERGY. Life as we know it involves movementof chemicals, of the body, of components of the bodyand a system with net movement cannot be in equilibrium. It must be an open and, in this case, metabolizing system. Many chemical reactions are going on inside the cell, and molecules are coming in from the outer environmentO2, CO2, metals, etc. The organism's system is parsimonious; many of the chemicals are recycled multiple times in an organism's lifetime (CO2, for example, is consumed in photosynthesis and then produced by oxidation in the system), but originally they enter the living system from the outside, so thermodynamicists call this an open system. Because of the many reactions and the fact that there is some gain of entropy (the mechanical analogy would be friction), there must be a compensation to keep the system going and that compensation requires a continuous source of energy. The major source of energy in Earth's biosphere is the Sunalthough life on Earth gets a little energy from other sources such as the internal heat of the Earthso the system can continue indefinitely by cleverly recycling chemicals as long as it has the added energy of the Sun to compensate for its entropy changes.

The fifth pillar is REGENERATION. Because a metabolizing system composed of catalysts (enzymes) and chemicals (metabolites) in a container is constantly reacting, it will inevitably be associated with some thermodynamic losses. Because those losses will eventually change the kinetics of the program adversely, there must be a plan to compensate for those losses, that is, a regeneration system. One such regeneration system is the diffusion or active transport of chemicals into the living organism. For example, CO2 and its products replace the losses inevitable in chemical reactions. Another system for regeneration is the constant resynthesis of the constituents of the living system that are subject to wear and tear. For example, the heart muscle of a normal human beats 60 times a minute3600 times an hour, 1,314,000 times a year, 91,980,000 times a lifetime. No man-made material has been found that would not fatigue and collapse under such use, which is why artificial hearts have such a short utilization span. The living system, however, continually resynthesizes and replaces its heart muscle proteins as they suffer degradation; the body does the same for other constituentsits lung sacs, kidney proteins, brain synapses, etc.

This is not the only way the living system regenerates. The constant resynthesis of its proteins and body constituents is not quite perfect, so the small loss for each regeneration in the short run becomes a larger loss overall for all the processes in the long run, adding up to what we call aging. So living systems, at least the ones we know, use a clever trick to perfect the regeneration processthat is, they start over. Starting over can be a cell dividing, in the case of Escherichia coli, or the birth of an infant for Homo sapiens. By beginning a new generation, the infant starts from scratch, and all the chemical ingredients, programs, and other constituents go back to the beginning to correct the inevitable decline of a continuously functioning metabolizing system.

The sixth pillar is ADAPTABILITY. Improvisation is a form of adaptability, but is too slow for many of the environmental hazards that a living organism must face. For example, a human that puts a hand into a fire has a painful experience that might be selected against in evolutionbut the individual needs to withdraw his hand from the fire immediately to live appropriately thereafter. That behavioral response to pain is essential to survival and is a fundamental response of living systems that we call feedback. Our bodies respond to depletion of nutrients (energy supplies) with hunger, which causes us to seek new food, and our feedback then prevents our eating to an excess of nutrients (that is, beyond satiety) by losing appetite and eating less. Walking long distances on bare feet leads to calluses on one's feet or the acquisition of shoes to protect them. These behavioral manifestations of adaptability are a development of feedback and feedforward responses at the molecular level and are responses of living systems that allow survival in quickly changing environments. Adaptability could arguably include improvisation (pillar number 2), but improvisation is a mechanism to change the fundamental program, whereas adaptability (pillar number 6) is a behavioral response that is part of the program. Just as these two necessities are handled by different mechanisms in our Earth-bound system, I believe they will be different concepts handled by different mechanisms in any newly devised or newly discovered system.

Finally, and far from the least, is the seventh pillar, SECLUSION. By seclusion, in this context, I mean something rather like privacy in the social world of our universe. It is essential for a metabolizing system with many reactions going on at the same time, to prevent the chemicals in pathway 1 (ABCD for example) from being metabolized by the catalysts of pathway 2 (RSTU). Our living system does this by a crucial property of lifethe specificity of enzymes that work only on the molecules for which they were designed and are not confused by collisions with miscellaneous molecules from other pathways. In a sense this property is like insulating an electrically conducting wire so it isn't short-circuited by contact with another wire. The seclusion of the biological system is not absolute. It can be interrupted by feedback and feedforward messages, but only messages that have specifically arranged conduits can be received. There is also specificity in DNA and RNA interactions. It is this seclusion of pathways that allows thousands of reactions to occur with high efficiency in the tiny volumes of a living cell, while simultaneously receiving selective signals that ensure an appropriate response to environmental changes.

Now, the only reason the evos won't attempt to define life is because it resticts them on their origin of life mythologies. Sad, sad, sad.


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frako
Member
Posts: 2814
From: slovenija
Joined: 09-04-2010


Message 44 of 268 (592914)
11-22-2010 6:44 PM
Reply to: Message 43 by AlphaOmegakid
11-22-2010 6:34 PM


Re: Sad Sad Sad
Now, the only reason the evos won't attempt to define life is because it resticts them on their origin of life mythologies. Sad, sad, sad.

ORLY

So how do creos, id-ists,... define life? If the rock got breathed on its life if
not its a rock?


This message is a reply to:
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Omnivorous
Member (Idle past 1132 days)
Posts: 3808
From: Adirondackia
Joined: 07-21-2005


Message 45 of 268 (592915)
11-22-2010 6:45 PM
Reply to: Message 43 by AlphaOmegakid
11-22-2010 6:34 PM


Re: Sad Sad Sad
How nice.

And where was this peer-reviewed piece recently published?

AbE: Ah, by the grace of google, I see--a Special Essay published in Science--not peer-reviewed, per se, since it isn't research..

So?

Edited by Omnivorous, : as above


Dost thou prate, rogue?
-Cassio

Real things always push back.
-William James


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