Life is short

Continuing with rather philosophical musings about life, Ed Trifonov has recently suggested a new approach to defining life:  let’s just vote on the definition.
So how does that work? And why should it work in the first place?
Note that I am diving straight into the subject, and not prefacing this post with a review of the various definitions of life. I assume that this blog’s readers have been exposed to some aspects of the debate on how to define life. Wikipedia and the references therein are a decent starting point, in case you want to refresh your memory. But just so we have something, here is the definition from the American Heritage dictionary:
LIFE:  the condition that distinguishes organisms from inorganic objects and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally.
Trifonov’s rationale for doing what he does is as follows:
The definitions [of life, IF] are more than often in conflict with one another. Undeniably, however, most of them do have a point, one or another or several, and common sense suggests that, probably, one could arrive to a consensus, if only the authors, some two centuries apart from one another, could be brought together. One thing, however, can be done – sort of voting in absentia – asking which terms in the definitions are the most frequent and, thus, perhaps, reflecting the most important points shared by many. Such analysis is offered below, revealing those most frequent terms that may be used for tentative formulation of the consensus.
Where to start?  Trifonov decided to take two book chapters which together list 123 non-redundant definitions of life. He then counted the words in those chapters, omitting connecting words and grouped them by meaning , then ordered them by the definientia (the words serving to define another word or expression) frequency (click to enlarge):

By word count, seems like life has mainly to do with living. Well, no surprises there, but somewhat tautological and less-than-informative.  However, rejoice O system biologists, for SYSTEM is the second most frequent keyword grouping. Then we have organic stuff, CHEMICAL, COMPLEXITY, REPRODUCTION with ENERGY and ABILITY trailing. Trifonov continues:

Thus, the consensus of the life definition patched from these nine definientia would be: Life is [System, Matter, Chemical (Metabolism), Complexity (Information), (Self-)Reproduction, Evolution (Change), Environment, Energy, Ability,…] where the square brackets correspond to some compact expression containing the words listed within. For example, one possibility is:

Life is metabolizing material informational system with
ability of self-reproduction with changes (evolution),
which requires energy and suitable environment.    

(I added the underlines.) Hm.  Actually, not bad for a definition culled from a simple exercise in word counting. Of course, to put these definientia together one would need some knowledge of life, this the exercise is not completely automatic and unbiased, nor does it profess to be so.

But Trifonov wants to condense this definition even more. To quote Hemingway: “boil it down; know what to leave out; tell a story in six words”. Is there still some redundancy in the definientia themselves that would let us boil it down and tell the story in only six words? Trifonov argues that metabolism implies the existence of energy and materials.  Whereas the existence of materials already implies a suitable environment. But self-reproduction subsumes all the above, as it requires metabolism, energy, materials and environment. However, variations and self-reproduction  are actually mutually exclusive. Both must be noted. The boiled down, Hemingwayan definition would therefore be:

 Life is self-reproduction with variations.

And, to top it off, six words! Hemingway achievement unlocked.

Of course, this succinct definitions renders all sorts of problems. trifonov admits to that:

One unforeseen property of the minimalistic definition is its generality. It can be considered as applicable not just to “earthly” life but to any forms of life imagination may offer, like extraterrestrial life, alternative chemistry forms, computer models, and abstract forms. It suggests a unique common basis for the variety of lives: all is life that copies itself and changes.

Here is where I think things go a bit too far: is self-reproducing (and mutating) software alive? Is the Weasel program alive? Are viruses alive? All of those examples fulfill, at least technically, the above definition. In a previous post, I talked about going from life to non-life on a scale roughly correlating to size and thus the amount of information and sustaining materials life can carry with it. The difference between life and non-life seems to be not only in self-reproduction with variations, but the ability to do so at some level of autonomy. When adding the caveat of autonomy, viruses are not alive, since they require the transcriptional and translational machinery of their host cells. Neither are organelles such as mitochondria, since most of their proteins are encoded by the nucleus. But requiring autonomy raises another problem, which I find hard to solve: how far does this requirement of autonomy go? After all, all heteretrophs are, to some degree non-autonomous, as they require basic materials produced only by autotrophs. So the definition becomes fuzzy again: humans are alive, although they cannot self-sustain without plants. Plants are alive, but they cannot fix nitrogen and require bacteria to do so. So are we to say that  autotrophic nitrogen-fixing bacteria the only living species on earth?  So maybe the autonomy criterion be limited to self-reproduction rather than metabolism? But those are hard to separate: without sugar, there is no DNA. Without essential amino acids, which most heretrophs acquire by consuming other organisms, there are no proteins to effect reproduction.

despite the difficulties,  my definition would be (seven words, unfortunately):

 Life is autonomous self-reproduction with variations.

 Fuzzy? You betcha. That’s life.

PS: as you can see from the article’s Pubmed page, it generated a flurry of comments. Those make for a great read too. Enjoy.



Trifonov EN (2011). Vocabulary of definitions of life suggests a definition. Journal of biomolecular structure & dynamics, 29 (2), 259-66 PMID: 21875147

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69 Responses to “Life is short”

  1. Ben says:

    Self-reproducing: last member of a bisexual species, either sex. Can’t reproduce. Possibly immortal. Still alive.

    With variety: Nope, no variety either. Just that one individual. Still alive.

    Back to the drawing board, friend.

    And just as an aside, you’re not even looking in the right place.

    Hint: All life process materials and/or energy from one form to another to aid in the pursuit or execution of yet another, relatively higher level process.

    Viruses, germs, people, frogs, grass, aliens, algae, and AI, nascent (almost non-existent) as it is or as advanced as you care to imagine it, all will do this. Because that’s what life consists of. Reproduction is a side issue at best, and certainly not a requirement.


  2. Augustus says:

    I’ve been thinking about this for some time, and could simplify it – If it evolves, it’s alive. This does away with a whole lot of problems and lets us think in terms of what might be alive rather than limiting ourselves to what we already know is alive. Also it encourages us to think of life in terms of systems rather than individuals, something which initially looks reasonable but which isn’t that useful.

  3. ATBS says:

    Earth life depends on the existence of the earth, or something else (it’s hard to say exactly what’s depended on, but the life that we know is not existing by itself). Things that exist in a computer, like software, can’t be excluded from the definition on the basis of not being autonomus, because the life we know isn’t autonomous either.

  4. MS says:

    It has already been done; “Life is life.”, Opus 1985

  5. Lee says:

    I think a lot of the problems around the definition of life is that most thinking is underpinned my an implicit definition “Like porn, I know it when I see it”. When I was at school we had a definition using several nice, fairly abstract, phrases about consuming stuff and producing waste – and right at the end was something like “must have a cellular structure”, because fire would be life under all the other parts of the definition but “everyone knows” fire isn’t alive.

  6. Shuckster says:

    @Ben: Entropy rather forbids life from being anything *other* than a reproduction issue, let alone a side one, and also makes immortality all but impossible.

  7. Dias says:

    Life is more so about autonomous adaptation to environment than reproduction or variation.

    And you just know somebody’s going to try to use this as an argument against homosexuality.

  8. AdamH says:

    LIFE: the condition that distinguishes animate objects from inanimate objects, exhibiting some ability and drive to preserve its existence through consumption, reproduction, and adaptation.

    how’s that? i believe it’s hard to find a perfect definition of life because there is no perfect life, hence ‘exhibiting some ability and drive’ as opposed to stating more definite conditions. what i find shocking is the rarity of a definition that describes the powerful ‘desire’ or drive of life to keep living. that seems to be the one universal trait of all living things – the drive to keep on keeping on 🙂

  9. AdamH says:

    edit: the drive to keep on keeping on AND consumption to that end seems universal.

  10. Nash says:

    Life as we know , is a continuum. By trying to define what is ‘alive’, an attempt is made to draw a line through a what is a extremely large and complex tree that extends from the non-living to the living (and we are not even taking about physical scale here).

    As a thumb rule, humans find things to be more alive based on their complexity – which manifests as the various ‘features’ of life we provide: adaptation, reproduction etc. etc. However, a little bit of thought exposes the fallacy in this thinking:

    1. A virus is more alive than a prion (thought not as alive as a cell)

    2. What makes the virus more alive? It has certain features of life because it is more complex – it carries extra information.

    3. Life has its features because of the information it holds, and pretty much at the core of life is the flow of information – from the environment to the ‘living entity’, or between the generations of the living entity. In essence , reproduction is the transmitting of information from one entity to the environment, in order to arrange elements and molecules into a copy of itself.

    4. Variations are inevitable due to the second law of thermodynamics

    At this point, it is clear that plenty of ‘non-living’ systems also satisfy these criteria.

    And that is why attempting to define life is like attempting to define the point where grunts and noises turn into language. There is no sharp point just a broad continuum.

  11. Glenn says:

    “Life is self-reproduction with variations.”

    Is the process of nuclear fission alive ?

  12. Grey Tide says:

    “Can you kill it?”

    There, did it in four.

  13. AdamH says:

    that last individual of a bisexual species still has the ability to reproduce. however, like me, he lacks the opportunity 🙂

    after some thinking, i’ve revised my definition of life…
    LIFE: a condition where an object exhibits some ability and drive to preserve itself and consume external material for internal use.

    Life is consuming and self-serving 🙂

    i don’t think fire would qualify according to that definition because the material has to be consumed for internal use. besides, fire is not an object or something that is performing consumption or conversion. fire is the actual consumption/conversion process as it appears to our eyes. the chemical reaction glows.

  14. Gibbon1 says:

    Life is a thermodynamic machine under programmatic control.

  15. AdamH says:

    hmmm…change ‘consume’ to ‘convert’ in my definition

  16. Bill Gaede says:

    Life has NOTHING to do with reproduction, eating, or any of the other poppycock invented by the Mathematical Establishment.
    life: that which naturally moves of its own volition against gravity.
    Only life has the ability to counteract gravitational attraction. That’s the universal property that all life shares.
    The bird brains of the Mathematical Establishment never figured this out in 10,000 years and never will. They will continue to gawk until the end of time asking the same questions over and over. “What is time?” “What is life?” “Why are we here?” “Does God exist?” In a decade, the next generation of lame brains coming out of college will ask the same questions and brainstorm the same stupid answers. “What could life possibly be?” “Does it walk? Does it fly? Does it reproduce? Does it eat?” “X eats but does not reproduce and Y reproduces but doesn’t eat.”
    In Science, we define strategic words such as object, exist, life… UNAMBIGUOUSLY. That way there is no ambiguity as we see today in the religion of Mathematics a religion which deceptively poses as Science and Physics! A scientific definition is one that can be used consistently. Only then is the proponent explaining rationally and can be understood.

  17. Merlin says:

    @Shuckster: by your reasoning, entropy makes any self reproducing organism impossible. We are, in one very real sense, immortal, in that there has been an unbroken chain of living tissue traceable from child to mother all the way back till when our great to the nth ancestors were first contemplating sexual reproduction, oh and is that a glint in that other slime’s eye?, and even further back through budding and other asexual reproduction tricks.

    Each cell budded off another cell. Every now and then, the child cell and the parent cell went their seperate ways and became independent organisms. Life has a funny way of concentrating order and holding back entropy, and there’s no known theoretical limit on how good life can get at that, provided a sufficiently large, remote, and hot power source.

  18. Shuckster says:

    @Merlin: Reasoning? My post was many things, but I hardly think it was reasonable. 😛 Anyway, I don’t think my post implied anything of the sort.

    The process of entropy makes life possible, not impossible. Your post pretty much describes why this is so – the life/death cycle.

    What I was getting at is that without reproduction (at all levels, macro and micro) life-forms would not be able to evolve because of the processes of entropy. But entropy is offset by the power of the Sun, and the Earth is in just the right place to strike a balance between a source of energy and the capacity to use it.

    Ben suggested that it might be possible for a bi-sexual life-form to exist indefinitely. I say he’s wrong. If it *is* possible on the macroscopic level, certainly there would need to be continuous reproduction at the microscopic level in order to maintain the organism, and there would need to be a source of energy in order to offset the processes of entropy.

    But since entropy will ultimately claim the entire universe I don’t think immortality is possible.

  19. Winston says:

    One (pedantic) scenario where that revised definition doesn’t work: what if I go on a hunger strike and hold my breath?

    @Bill Gaede
    I’d imagine that there are forms of life that do not act against gravity. Algae, perhaps? Also, if someone goes into space, there’s no gravity to act against (if they’re in free-fall) … but they’re still alive.

    I offer no counter proposals, best one so far is “Life is life.”

  20. Kenny says:

    If it exists, it’s alive.

  21. Brandon says:

    IMHO, the “Autonomous” bit isn’t perfect. You’re trying to paper over the cracks in the generalization, but with the wrong tool. For instance, if hypothetical Strong AI were to emerge, it might fail “Autonomy” because it relies on human computer infrastructure. I think a better amended variation would be: “Life is self-reproduction with unbounded capacity for evolutionary variation”. In other words, given enough time it could evolve into anything it wants; there are no artificial or design-inherent barriers to the species’ future abilities because the theater in which is operates is the one of nature itself, which is true of all natural life as we know it to day (whereas Weak AIs that use rudimentary “genetic algorithmis” have the capacity only for variation within a rather bounded and limited domain). I suspect my definition includes biological viruses, and I’m actually ok with that. It’s within the realm of possibility that a virus could eventually evolve to be indistinguishable by such trivial measures as Autonomy.

  22. Archimedix says:

    Life posesses the capability for continuous adaptation, which means it can develop and adjust to its environment.

    A satisfactory definition of life should not only account for biological life as we know it but also take into consideration artificial / synthesized life forms.

    Reproduction is not a necessary requirement for life albeit it may be almost sufficient (not entirely though… things like fire and crystals such as ice can reproduce and spread).

    An organism dying because it loses the ability to reproduce in any form (i.e. it cannot create offspring and cannot create new cells, for example, the cells of a nuclear radiation victim lose the ability to split and repair themselves).

    Common sense tells us that a dying organism is also considered alive until the organism is dead, and organisms that are not able to reproduce may still be alive, and this does not only apply to multi-cell organisms (think of biological rights management (analogous to DRM) as done by Monsanto et al. to prevent genetically modified organisms from creating offspring).

    I think that some form of development or the potential thereof and some form of metabolism (at least energe-wise – i.e. there is some input, a transformation / processing of inputs and some output) are mandatory for something to be considered life.

    Artificial life forms may have one criterion that substitutes the requirement for reproduction, and that is intelligence.

    Intelligence and evolution are both manifestations of development, or at least the potential thereof.

    A thinking machine might never have or develop the ability to reproduce due to its confined intelligence or because it does not have access to hardware for doing so, but I bet you would consider it to be alive (this is similar to people with brain damages or diseases that confine the potential of their minds).

    Development (or the potential thereof) is sufficient to rule out fire and maybe crystals as forms of life.
    Note however, that there may be quasi-crystals which create new patterns whenever they grow, so that may be considered development.
    Additionally, one may note that the formation of particles, atoms, molecules, stars, planets and galaxies constitute some form of development as well.

    So adjustment (or the potential thereof) may be another criterion going along with development, leading to the concept of adaptation.

    Hence, I consider continuous adaptation or a potential thereof a pretty good criterion for life as it is necessary and maybe somewhat sufficient.

  23. I prefer a variation of Augustus’ version: “If it evolves, it’s alive.” Or, to go back to the dictionary definition you started with: “adaptation to environment through changes originating internally.”

    “life is the process of adapting” (evolving in environment) or, collapsing ‘adapting’ and ‘evolution’,:

    Life is Learning.

  24. Bob Strawn says:

    Life is what some people, you know who you are, should obtain one of.

  25. Gopal says:

    Without including the concept of self-awareness (which includes self-preservation at one end and empathy at the other), the definition of life will remain incomplete.

  26. Archimedix says:

    Self-reproduction by the way is never necessary for life.

    Life can be produced by an external entity (a “factory”) which itself does not even need to be alive.

  27. Archimedix says:

    Oh, forgot to say… viruses are passive life – they are being lived. Nonetheless I consider them a form of life or proto-life.

    Prions are similar to viruses, but even more primitive. They do not have any DNA.
    They are just proteins, but they can apparently adapt and are reproduced like viruses.

    Evolution is just one aspect of adaptation. It requires substitution or succession of individuals and selectional pressure.

    Self-awareness as we commonly understand it is a pretty sophisticated phenomenon and should undoubtedly be a sufficient condition for life, as is “true” intelligence by itself already (intelligence is the capability to adapt by learning and to infer, conclude, act and react using learned knowledge). Intelligence is probably necessary for “true” self-awareness (I assume that by self-awareness you do not mean any type of self-perception but also the ability to obtain new knowledge from self-perception; any cybernetic system is able to receive input originating either directly from itself or from input caused by itself).

    @Bob Strawn:
    Life as you mean it should not be reduced to life outdoors and adventures.
    Many people indulge in thinking about philosophical and scientific topics, which is naturally just a fraction of their maybe very satisfying and wonderful lives.
    What you said just proves how arrogant some people can be, making assumptions of and trying to decrease the value of other people’s lives possibly in order to make oneself feel superior or whatever reason.

    Life may be learning, but I fear some people might never learn.

  28. GregD says:

    What is the goal of defining life? Our ethical, emotional and intellectual biases make defining life difficult because each limit we place upon the definition reflects one of these biases.

    In legal terms these definitions could be used to exclude viruses and prions, but also in-fertile couples, mules, etc.

    If life is taken in the context of an environment then a computer virus that does not change is not life but a virus that does change could be life.

    I think the best way to judge a definition of life is to imagine it being argued in a court of law. When we finally have a definition that does not exclude what we “know” is life and does not include what we know “is not life” then we’ll have it. Good luck with that.

  29. rehto says:

    Living. Unknowable perception. Too simple to explain.

  30. vicV says:

    I gravitate torwards, “Life is learning to live” or like Augusts’ and Boulton’s- “life is the process of adapting” Which is curious, in a minute. I’m pretty sure the Earth is alive, yet it doesn’t reproduce, so any definition would have to be inclusive, and consequently fuzzy. If you narrow out the Earth from one’s definition I could only conclude you’re Death Eaters and scheduled for destruction with the rest of the House of Snape. But the curious thing, Calcite crystal strain harden, and retains memory of strain in up to three directions. This would imply it’s adapting to strain by becoming harder the more it is strained. At a point, it utterly fails, but that’s not my main point. Definitions don’t draw lines so one can see more narrowly, but so as to allow one to shed light on other things in new ways for a more fuller understanding. Like the law of Gravity, it doesn’t tell us what gravity is, but gives us understanding in how to view the world. Do not fall into the teapot when trying to make a cup of tea.

  31. webdawg says:

    Atoms live. Long live the materials of this univerise!

  32. Zach says:

    “Life is self-reproduction with variations.”

    It struck me how similar this is to philosopher Francis Hutcheson’s definition of beauty as “uniformity amongst variety.”

  33. flamoot says:

    Not everything that evolves is alive. Even geology evolves << evolving electronic consciousness

  34. Anonymous Coward says:

    Drop the “with” and you’re back to 6 words: Life is variable, autonomous self-replication.

  35. Ben says:

    @Shuckster: “Entropy rather forbids life from being anything *other* than a reproduction issue, let alone a side one, and also makes immortality all but impossible.”

    No. Babies, children exhibit strong dominance over entropy. Entropy only begins to win when our systems stop dealing with cell replacement properly. Confirmation of this can be found in extremely long-lived organisms. This is a technical issue related to evolutionary consequences and I have extremely high confidence we can solve it.

    @AdamH: “that last individual of a bisexual species still has the ability to reproduce.”

    No. A bisexual species requires one member of both sexes to reproduce. The last member, by definition, only represents a portion of the reproductive mechanism.

    “a condition where an object exhibits some ability and drive to preserve itself and consume external material for internal use.”

    Mmm. Not bad. You’ll get some process-based objections, like oxidation (fire, rust, etc.) but still, not bad at all.

    @BillGaede: “Only life has the ability to counteract gravitational attraction.”

    No. Boulders and rocks can roll uphill in the wind. Evaporation of water. Smoke. Volcanic ash plumes. On the other hand, lichen have no particular ability to counteract gravity, nor do viruses… they go where the environment takes them, no more.

    @ David Boulton “If it evolves, it’s alive.”

    No. Evolutionary software, which isn’t alive by any stretch of the imagination, exhibits every characteristic of evolution, which is really no more than environmental factors pruning less- or un-successful variations, in the context of that environment, on a theme. For example, crystal growth (we’re talking about rocks, now) can obtain multiple possible forms, but the environment (temperature, pressure, material distribution, etc.) will prune away all but the form or forms that can accrete in that specific combination of environmental factors.

    @Gopal: “self-awareness”

    No. Germs, viruses, grass, etc.

  36. Synlap says:

    Life is what _I_ think it is.
    Life is what _you_ think it is.
    Note: If we don’t agree about a specific item being alive, then _you_ are wrong.

  37. Synlap says:

    i.e. “Beauty is in the eye of the beholder”…

  38. Synlap says:

    As a cheap paraphrase:

    “Life is determined in the mind of the beholder”…

  39. Gopal says:


    Self-awareness : ranges from self-preservation to empathy.

    All (grass, virus and germs) of them show ‘self-preservation’ – especially so if you consider reproduction as a means of self-preservation.

    So, yes, “germs, grass, virus etc” are ALL included.

  40. OHooligan says:

    Badly paraphrasing Richard Dawkins “Selfish Gene” in 6 words:

    Replicator’s vehicles evolved by natural selection.

    Probably needs a few pages of footnotes to define at least 5 of the words above. Or 6 if we can’t agree on the meaning of “by”.

  41. Steve says:

    I believe living entities reduce local entropy, while increasing global entropy. Systems that increase global entropy fastest “out-compete” others.

  42. Somebody says:

    As far as life already have certain commonly known properties like adaption, evolution – no any live creation have final rights to draw limits of it.

    At first, there is not all physical laws discovered, not talking even about all inter-dependencies between “non-living” material and live creation.

    In other words, for any given moment – you can do it only if you have all experience and knowledge of whole world concentrated into your head for that given moment. After one second your previous description will be already wrong, because of you didn’t take into account some new discovery – even new creation, probably.

    You can have only rough definition (or set of rough definitions) that takes into account common public knowledge and that’s it.

    What about to discover something really important first ?
    – like some physic law, we are lacking of ?
    – And what is more important: share it with public, not keep it into secret for military needs…
    After that we could update our definition of life, i agree.

    So, this is a waste of time for now.
    – my opinion.

  43. Somebody says:

    Please excuse me for some commas or syntax. My native language is not English. Should learn it more. Hope it is still guessable what i want to tell.

  44. Miguelo says:

    I have to respond to the first comment by Ben. Reproduction is the mechanism by which life adapts. Environments change. The reason there is no such thing as an immortal being is that it would not be able to adapt to change, and change is a given in any definition of a universe. And even if you take it down to the cellular level: do cells not divide? You simply can’t escape reproduction in defining life.

  45. RHEanes says:

    Everything in existence is a machine of some sort…. a chemical machine like a body, or an artificially intelligent program. Everything in existence and be defined this way without an exception as far as I can see. What happens after the machine breaks is what fascinates me about the definition of life. What happens after death is unknown, but many theories or posits exist. Assuming that we are not our body, and that we may or may not exist after the machine breaks, we can define life as consciousness. Is a virus conscious? It kind of depends on how you define it. Assuming consciousness is defined as: a system where a model existing internally is used to act on the systems environment. Given that definition then, yes, a virus or prion would be considered life. This would also be true computer programs. But are computer programs alive. I’ll go back to the line of thought I started with. Can the system be killed? when it is killed, will it defend itself? If so then, yes, it is alive. Adaption and reproduction are defense mechanisms to insure the continuation of life and information.

    Life would therefore be defined as : A system that utilizes an internal model of it’s environment in order to act on that environment.

    It is interesting to me that the quip: can you kill it? is actually very true and proof of life.

  46. Michael says:

    interesting. i read the 6 word def, began to read your critique, and said to myself: computer programs self reproduce at our behest, within a controlled environment (the computer). The word Autonomy needs to be added to make it work. and then i read down a bit further. good job!

  47. Winston says:

    This might be over-ambitious, but how about: A system that works to reduce local entropy.
    Are reproduction and self-preservation not simply possible methods of achieving this? Hopefully this definition precludes a refrigerator from being defined as alive.

    I’d argue that the Earth itself is not alive, any more than a termite nest is alive (that’s just a mud shell, filled with life). And on the Earth as a whole, surely, entropy increases.

  48. Sephira says:

    Life Is

    done it in two 😛

  49. Somebody says:

    To: Winston
    Life for you should be absolutely everything you can reach in your reality and your imagination.
    Everything is a part of system. Nothing is random in that system.
    Earth itself is a part of system as well. You just can’t tell for sure it’s system size and age.
    You can’t tell for sure what is local entropy for Earth. That’s why you conclude earth is not alive.
    You can’t tell for sure living cycle of things around you. That’s why you conclude these things are not alive.

    Consider “stupid” example:
    Your chair “is not alive” by your definition and any of these previous definitions. Are you sure ?
    Let’s try to apply living creature properties for it and compare.
    Chairs do not reproduce self. Are you sure ?
    Can it be so: ? – Everything what is needed for chair “self reproduction” is the worlds with 3+ dimensional physical conditions and human-like creatures understanding of what is chair. Roughly – that is environment and conditions for “local entropy reduction” of chairs.
    Chair cannot be “killed”. Are you sure ? If you can’t do something in your current world – does it mean it can’t be done in whole system ?
    Let’s say: stop chair production in your world, and chair “self reproduction cycle” will be broken only for this location of their usual existence. By that you will “kill” it on the Earth.
    You will not do it, because of you are not stupid enough to leave your back and backs of other humanoids without this GREAT CREATURE of their mind AND REALITY. That is greatest self defense of this living creature from being “killed” on Earth.
    So, let’s return to our previous definitions, because of we are each in certain step of evolution and have just limited knowledge and understanding of how whole system works and why it works.
    New definition of what is life we could derive only after we will reach next step of our knowledge and understanding of whole system.

    Any rock is a part of whole system. It was not get here in random way. It is your assumption only – it get here random way, because of you do not understand it’s living cycle. It is part of your environment what is necessary condition for the planet on which you are living. Whole planet and any rock on it have it’s own life cycle. It is not comparable to yours, – that’s why you conclude it is not alive.
    Every single atom in your body could originate from any single rock on this planet previously.

  50. Stephen Kellett says:

    “If it evolves it is life”. Problem with that is apparently alligators and crocodiles are not alive. They haven’t changed much in millions of years. They are perfectly adapted to their situation. No requirement to evolve in such circumstances.