Talk:Life

Automate archiving?

Does anyone object to me setting up automatic archiving for this page using MiszaBot? Unless otherwise agreed, I would set it to archive threads that have been inactive for 30 days.--Oneiros (talk) 18:30, 2 January 2010 (UTC)

I agree with automated archiving of inactive threads. --BatteryIncluded (talk) 17:21, 5 January 2010 (UTC)

Y Done. The bots should start in the next 24h.--Oneiros (talk) 18:46, 5 January 2010 (UTC)

Excellent sources

• Pace 2001.
• McKay 2004 Tim Vickers (talk) 23:48, 1 February 2010 (UTC)

Indeed. --BatteryIncluded (talk) 03:16, 2 February 2010 (UTC)

Broken link in references

There's a broken link in the references - here is the correct address http://www.astrobio.net/exclusive/226/defining-life —Preceding unsigned comment added by EfAston (talk • contribs) 04:21, 25 March 2010 (UTC)

Fixed Locos epraix ~ Beastepraix 08:45, 16 April 2010 (UTC)

Definition of Life

I'm no expert but I am a pedant. The definition of Life in the opening paragraph is clearly misleading. To say that an ability to reproduce is a prerequisite to be considered as alive is patently wrong. Many organisms as members of animal populations may be unable to reproduce through accident or disease for example, and yet by any common-sense measure they must be considered as being alive. On a similar point, it could be argued that humanity as a species has stopped evolving in response to environmental stimuli simply because human-kind has the ability to adapt its environment immediately to its requirements, and yet, again, any living member of the human species is obviously alive.Fizzackerly (talk) 21:25, 13 June 2010 (UTC)

The opening paragraph defines life as "objects that have signaling and self-sustaining processes (biology) [versus] those that do not". It does not mention reproduction. If you're going to be a pedant, at least be an accurate pedant :P

Touche! On the substantive point I reckon I could make a fairly sound argument that stars are alive given the opening paragraph definition you quote here. The size of a star is regulated by competing processes of gravitational collapse versus radiation pressure arising from thermonuclear reactions. Stars in binary systems signal by the transfer of matter giving rise to modified characteristics of both of the binary pair in respect of brightness and lifetime (pun intended). Just a bit of fun, but it shows what you can do with a definition. Fizzackerly (talk) 17:12, 20 July 2010 (UTC)

The second paragraph introduces the notion of "reproduction" as being one of the defining characteristics. I think you are suggesting that the sentence should more clearly indicate that it is describing the characteristics of species, rather than any individual entity from those species. It would help if you suggested a specific wording that you'd like to see. Personally, I don't believe it is confusing.

In a way you're quite right. However I'd suggest the only reason you don't find it confusing is because you know in advance what is intended by the statement. If you were trying to explain to the ubiquitous 'intelligent but ignorant correspondent' what the role of a capability in reproduction is in defining a living organism I reckon you'd come unstuck. Again suggesting the capacity to reproduce is a defining characteristic of a living species doesn't quite cut it either since one could imagine a species level 'event' such as a contagious disease which rendered all members of a species infertile but none-the-less alive until the species had become extinct via its failure to reproduce.

I don't know what the answer to this is except to say that it's probably as hard as defining other intangibles such as artificial intelligence for example. On the other hand I'd suggest that trying to pick out common characteristics of most living organisms isn't the best way to define what's alive and what's not, it's a kind of inductivist approach - just my opinion. For my taste I prefer a definition from thermodynamics along the lines of a living organism being something capable of maintaining a low entropy state by extracting free energy from its environment. I see that definition elsewhere in the article some way down but it sounds rather more fundamental than picking out some common characteristics of most living organisms. Fizzackerly (talk) 16:19, 20 July 2010 (UTC)

Saying that something which is considered alive is something which is "extracting energy" is arguably wrong too along the same thought processes as you have given. While a "life system" may continuously extract energy from the surrounding environment, that's not necessary either, and a life form can exist by being provided already with energy to allow it to function however briefly before dissipating. For example, someone could create an entity with fat storage "inside" the system after which using it up would dissipate the system i.e. causing death. I use the word "dissipate" because ultimately life is nothing more than the encapsulation of energy into an area or structure which is recognisable, typically with energy exchanges taking place within it. Using the term "inside" isn't accurate either since it doesn't matter where energy is occurring necessarily. You could say that the Earth's solar system is alive, or the entire universe. My point, and your point earlier as well, is that defining life as system which maintains itself ignores certain situations which one would want to use the term "life" for, like briefly-existing self-contained systems using energy already contained in the system and "extracting" nothing from the "environment". How about defining life as "complex energy", an "energy system", or any "machine"? This would attempt to segregate simple energy from energy systems and to avoid calling all energy "life". Yfrwlf (talk) 20:38, 14 December 2010 (UTC)

Regarding human evolution having ceased, (A) [citation required], (B) see Human evolution#Recent and current human evolution. HTH. -- Quiddity (talk) 23:41, 13 June 2010 (UTC)

The lead section is an introduction which by no means singles out the phenomena of reproduction as the decisive property of life. The definitions are in the "Definitions" section. Your suggestion to create a definition wide enough to include all possible "accidents or diseases" on a particular organism would be so vague that it would totally lack of practical meaning. Regarding humans having reach the pinacle of evolution, we would love to read the peer-reviewed research on that.--BatteryIncluded (talk) 17:31, 14 June 2010 (UTC)

Although a sterile mule does not reproduce, pretty much every cell it is made of can reproduce and evolve. If one of the cells became cancerous, the cell's decedents will try to expand their domain. We consider a mule to be alive because it is made up of living components. If a robot could mimic exactly the behavior of a mule but nothing in it reproduced I would say that the robotic mule was not alive. TheoThompson (talk) 23:35, 10 March 2011 (UTC)

dr. mult. Gerard Jagers op Akkerhuis: In relation to the above discussion points, I would like to suggest a simple, yet fundamental improvement of the wiki page about life. This involves the distinguishing between 'LIFE' and 'LIVING'. At the moment many criteria used in the wikipedia definition actually relate to 'living' (dynamic aspects such as signalling functions, metabolism, reproduction etc.). A frozen bacterium simply illustrates that this is not the most logical thing to do. While frozen, a bacterium is not 'LIVING' because it is frozen. It cannot signal, metabolize, reproduce etc. Yet, it still represents 'LIFE' because it can be thawed and activated again. From this example, it is straightforward to conclude that LIFE represents a specific kind of material organization that allows things to -when active- show 'living' activities. A logical next question is of course, what precisely are the organizations that define life. A framework for dealing with this question is presented in my second thesis (http://repository.ubn.ru.nl/bitstream/2066/82605/1/82605). An elaborate discussion of many aspects of how te define life can be found in my recent paper in Foundations of Science (http://www.springerlink.com/content/3420lw0ll3r5p7k0/). In this paper I offer a very fundamental definition of life that solves problems that plague existing definitions. If Wikipedia is interested, I would like to be involved in re-editing the definition of life such that it takes the above simple logic into account. As the definition of life topic has many links to other wiki pages (What is an organism? What is biodiversity?) I would prefer to work in close cooperation with the wiki team. You are welcome to contact me. Regards, Gerard. Jager008 (talk) 07:49, 12 June 2011 (UTC)

Hello Jager. Yes, defining life is quite difficult. I will certainly read your papers sometime tonight and likely comment later. As a quick note, in our research labs we do not refer to frozen bacteria (or eukaryotic cells) as living or alive, buy whether they are viable, eg: capable of life or normal growth and development. BatteryIncluded (talk) 21:46, 12 June 2011 (UTC)

FWIW - My Thinking At The Moment - "Life" (and/or "Life-Forms"), At The Most Basic Level, Simply Seems To Be *A Chemical That Can Reproduce Itself* - Interestingly, All Known Life-Forms Are Composed Of The Very Same Chemical (basically, a very particular form of phospho-sugar-nucleic acid) - Capable Of Astronomical Variation - With Only Variants Suitable To The Environment Surviving From One Generation To The Next - Apparently, All Life On Earth Can Be Traced To A Single Event Occurring About 3.5 Billion Years Ago - If Interested, Some Of These (& related) Comments Were Posted On My LiveJournal Some Time Ago - In Any Case - Enjoy! :) Drbogdan (talk) 00:06, 13 June 2011 (UTC)

Hello Jager, I do not have a subscription to Springer, and I would like to have a copy sent to me, please. I am sure Dr. Bogdan would like a copy too.  ;) I already sent you a private message within the Wikipedia system. By reading the abstract, it seems you coined innovative terminology and concepts. Your thesis is 288 pages long so I don't think I can process that tonight and discuss it; i may take me time to get in the swing of "operators" and "closures" since my field is strictly molecular biology. According to the rules in Wikipedia, if the concept is not too "fringe", and if the article is peer-reviewed, (which it is likely the case) I am sure we will be able to incorporate the essence of it in the respective section(s). Cheers, BatteryIncluded (talk) 02:35, 13 June 2011 (UTC)

Edited to add: it seems to me your thesis goes deeper than just "defining life", it seems a living system theory, which may have its own entry under "Living systems theories" in this article. My limited understanding of "living systems" is that they are at the vanguard as they attempt to unify our knowledge of all aspects of biology and environment. I for one am receptive to it; I hope Bogdan gets onboard so that Jager won't have problems with Wikipedia:Conflict of interest. -BatteryIncluded (talk) 03:04, 13 June 2011 (UTC)

At The Moment - And For Purposes Of An Encyclopedia - I Would Think Any Definition (and any related information in the lede) Re The "Life" Article Should Be As Accurate And As Easy To Understand As Possible - A Currently Conventional (and/or conservative?) Way Of Thinking Might Be Preferred To Any New One That Might Be Controversial, Unsettled And Untested - In Any Case - Enjoy! :) Drbogdan (talk) 13:50, 13 June 2011 (UTC)

For the lede section, I completely agree. Also for the definitions section, as the current understanding is descriptive. Although I have not finished reading the thesis, I am so far in favor of adding a short and concise entry on this theory under the "Living systems theories" section, if it was published in a peer-reviewed journal and we can get a copy of it. Cheers, BatteryIncluded (talk) 14:48, 13 June 2011 (UTC)

Yes, Seems We Entirely Agree About This - Thanks For *All* Your Comments - And - Enjoy! :) Drbogdan (talk) 15:19, 13 June 2011 (UTC)

Thank you all for the above discussions. Just a few short responses: The definition of life paper can be found in chapter 5 (pp 122-150 of my thesis, see link above)(I only added the Journal ref to show where it had been published). Indeed the thesis goes deeper that a definition of life, because a definition of life needs an underlying fundament. A link to living systems theory would be possible, say, as a means to indicate that alternative ways exist (additionally to living systems theory) to think about organization of the world. The basic idea of the operator theory, however, differs considerably in its strictness and simplicity and its more limited scope (In matters like these I regard limitedness as a virtue ;->). Hope discussions will remain focused on the simple difference between LIFE and LIVING (I discuss 'viable lifelessness' at page 134 of the definition of life chapter of my operator hierarchy thesis). The above remark of the "chemical that can reproduce itself" for me only illustrates the confusion about what exactly is life (hope this remark hurts no feelings!). As I stated above, reproduction is a property related to 'living'. And not a good candidate for a definition of life, because not ALL living things can reproduce, not even in potential (which debunks the criterion, at least in my eyes). So, the question remains: what structures fit a definition of life? If a virus molecule is looked at just for its structure, it has the structure of 'molecule'. And if we consider one particular molecule to have a structure defining it as life, we need to consider all molecules as life. So considering a virus as life seems not very satisfying because of the consequences this viewpoint has for all other molecules that belong to the same type of organization. Gerard Jagers 137.224.252.10 (talk) 09:51, 14 June 2011 (UTC)

@Jagers - Thank You For Your Comments - And For Pointing Out That "Life" And "Living" May Be Entirely Different Considerations - The Phrase "definition of life" Seems To Appear 70 Times In One Of Your Publications - But A Simple, Easy-To-Understand Definition Does Not Seem To Appear At All - The Closest "Definition Of Life" You Seem To Present, On 122 Of Your Publication, Seems To Be As Follows: "...matter with the configuration of an operator, and that possesses a complexity equal to, or even higher than the cellular operator." - Just Curious - And If Possible - In Simple, Easy-To-Understand, Every-day Language (suitable for a non-specialized encyclopedia with a world-wide audience), How Would You Briefly (in one-sentence) State The "Definition Of Life"? Drbogdan (talk) 13:04, 14 June 2011 (UTC)

Dear DrBogdan. My major drive in science is to make things simpler (Ockhams razor!). Therefore I really appreciate the point you raise. I have a simple answer. If one accepts that a complexity ladder can be build that ranks all types of physical particles and organisms, this ladder can serve as a basis for a simple definition. The complexity ladder I talk about (which I call the operator hierarchy) contains the following steps: quarks, hadrons, atoms, molecules, (bacterial) cells, endosymbiontic cells (frequently referred to as eukaryotes), endosymbiontic multicellular organisms (plants, fungy) and endosymbiontic multicellular organisms with brains. At every step on this ladder a new integrating property is added. The ladder is strict: every lower level is the immediate precessor of the next level. No step can be added or taken out. Using this organisation ladder as a basis, a very simple definition of life can be phrased as: "Life relates to the organizational properties that define all the system types on the ladder that at least show the complexity of the cell". This definition is simple (given the complexity of the problem!). It refers to the ladder and the ladder defines exactly which organizational properties we talk about. It respects that life applies to organisms with different levels of complexity (for example not only to the first cell!). It is more specific than autopoiesis. The use of the ladder as an underlying fundament also implies that the definition is highly specific in deciding on 'difficult cases'. As I have indicated in my definition of life paper, the use of this definition solves many problems that have plaqued this subject for so long. Kind regards, Gerard Jagers Jager008 (talk) 07:38, 15 June 2011 (UTC)

Thanks Again For Your Comments - Seems That Both Of Your "Definitions Of Life" Include Cellular life In The Definitions But Do Not Seem To Include Non-cellular life (or Acytota and Aphanobionta) Organisms - Like Viruses (including the Mimivirus), Viroids, Cosmids, Fosmids, Phagemids, Prions, Satellites, Transposons And Related Acellular Life Forms - OTOH, "Life" As A *Chemical That Can Reproduce Itself* Seems To Include Such Life Forms. For Me, At Least At The Moment, The Basic Essence Of All Life Forms, At The Most Fundamental Level, Is Chemistry - And Reproduction - As Before, "Life", Deep Down, Is *A Chemical That Can Reproduce Itself* - All Known Life-forms Are Composed Of The Very Same Chemical (basically, a very particular form of phospho-sugar-nucleic acid - capable of astronomical variation - with only variants suitable to the environment surviving from one generation to the next) - AFAIK, The *Purpose* Of *All* Life Forms Is To Get It's Genetic (or chemical) Information) Into *The Next Generation* - "Living" Is Simply A Way For This (chemical reproduction) To Happen - In Any Case - Thanks Again For Your Comments - And - Enjoy! :) Drbogdan (talk) 15:50, 15 June 2011 (UTC)

Dear DrBogdan. In the same way as I argued above that LIFE and LIVING shoud be separated, I argue that LIFE and REPRODUCTION should be separated. Not all forms of life can reproduce (e.g. a sterilized cat, my grandmother, species crosses, etc. etc.). Reproduction therefore is not a good criterium for life. Instead maintenence is crucial. Hope you are willing to adjust on these grounds your opinion that a reproducing chemical is life (this apart from the discussion about what is indicated with 'reproduction' in the above examples). Instead I would like to offer you the viewpoint of a set of chemicals together maintaining all molecules in the set (they do not reproduce but maintain as a set, so reproduction is not required). In a set A, B and C, A produces B, B produces C and C produces A. All still based on chemistry. Provide this set with a (chemical) membrane and this would offer the chemical basis of life. Together they are capable of maintaining themselves as a set. Please take the effort to read my definition of life paper, as this explains all this ste by step and in much more detail. Kind regards, Gerard Jagers Jager008 (talk) 18:38, 15 June 2011 (UTC)

I Think You May Have Misunderstood My Use Of The Word "Reproduction" - AFAIK, *All* Life Forms Reproduce - At The Cellular Level At Least (& at all possible times) - In Order To Be Considered Life Forms At All - Including Infertile Life Forms (mules, sterilized cats, etc) - In My View, Life Forms Are Basically Chemicals - Life Forms And Reproduction Are Intimately Integrated - Reproduction Goes On At Any And All Possible Levels Of A Life Form's Make-up - To Me At The Moment, This Makes The Most Sense - You May Wish To Re-Read My Comments Above With This In Mind - In Any Case - We Can Agree To Disagree On This Of Course - Thanks In Any Regards For Your Comments - And - Enjoy! :) Drbogdan (talk) 20:33, 15 June 2011 (UTC)

dear Drbogdan: In principle we may agree, but I prefer other choices. The use of the organization ladder as a basis for a definition of life does allow one to choose whatever level(s) for whatever definition(s). In relation to all biological knowledge (biology being the "study of life") it would be quite strange however, to include the level of molecules (which are chemicals). From a strictly philosophical point of view one could choose other levels on the ladder, and accept chemicals as being 'alive'. I do not advice that, however, as it leads to much more complex reasoning (Ockhams razor!). Kind regards, Gerard. Jager008 (talk) 22:25, 15 June 2011 (UTC)

FWIW - Of Possible Interest - Seems Others Have Defined "Life" Similar To The One I Posted Earlier [ie, "'Life' (and/or 'Life-Forms'), At The Most Basic Level, Simply Seems To Be *A Chemical That Can Reproduce Itself*"] - There Are Several Examples: One Astronomer Phrases It As "matter that can reproduce itself" (also, PDF-1 and PDF-2); Another Scientist(?) As "a molecule that can reproduce itself" - I Have No Particular Investment In Such Definitions For Purposes Of The Main "Life" Article But Perhaps Such Thinking Might Be Considered To Some Extent? - In Any Regards - Enjoy! :) Drbogdan (talk) 14:18, 14 August 2011 (UTC) - UPDATE -> Added A Brief Line Of Related Text (And Several References) To The Main Article. Drbogdan (talk) 13:27, 28 August 2011 (UTC)

Would not a better definition be "Life is that which has the discretionary use of energy"?Senseofwonder (talk) 02:20, 2 January 2012 (UTC)

Can you cite a reliable source for that definition? Everything that goes into an article in Wikipedia has to be verifiable from a reliable source. We cannot use material that is original research, that is, facts that we have personally observed but which are not supported by reliable sources, definitions that we have come up with ourselves, etc. -- Donald Albury 12:07, 2 January 2012 (UTC)

Thank you Donald. As a new comer to the world of wikipedia contribution I appreciate your clarification. I now recognise wikipedia's destinction between the production of new knowledge and the gathering and presentation of existing knowledge. I will look elsewhere for a forum to discuss refining the definition for life and meybe, in time, will arrive back here with the prerequisite citations. Thanks again.Senseofwonder (talk) 00:17, 3 January 2012 (UTC)

"Evolved strategies"

"Life has evolved strategies that allow it to survive even beyond the physical and chemical limits to which it has adapted to grow." - A rather problematic sentence. Life has a will to evolve strategies now? I don't think a teleological view fits into the general biological consensus, and thus it opposes the rest of the article. The other problematic suggestion is that life somehow has knowledge of some physical and chemical limits to which it can adapt.

Shouldn't we better drop the sentence entirely, and assume that robust designs survive better and thereby introduce the subject of extremophiles by more truthfully suggesting that this class of creatures adapted to a changed environment and then adapted again until survival was possible in conditions that are anthropocentrically deemed extreme? --JeR (talk) 16:36, 30 June 2010 (UTC)

I agree. Go ahead and do the change. Cheers, --BatteryIncluded (talk) 02:43, 1 July 2010 (UTC)

Life wordle

Wordle constructed from Wikipedia article, Life, with "life" terms removed. Available at Wordle gallery.

I recently started playing with "Wordles'" and thought they could be an interesting tool to help review the coverage and balance in Wikipedia articles. For example, here's a wordle of the Life article with the term "life" removed.

A quick view of this wordle suggests the article emphasizes discussing life more in terms of living organisms, Earth, systems, the environment, animals and RNA. If so, is that intentional? As it should be? Does a visual aid like this help discussions about coverage and balance? What do you think?

In any event, using the Wordle app was a fun exercise. Do any other articles seem to be itching for their own wordle? Regards, RichardF (talk) 22:23, 22 January 2011 (UTC)

Dear RichardF, the point you raise is very intersting. It indicates that the present definition of life in wikipedia centers around organisms. This is in part very logical. But it implies kicking the can down the alley. Next question then is how to define the organism. Here anyone can find that Wikipedia defines an organism as a living system. A circular reasonig! To solve this problem I have suggested above (definition of life) to use a complexity ladder for particles and organisms (whith the name of the operator hierarchy). Now a section of the ladder can be used to define the organizations representing life. And the systems in the section of the ladder representing life can be named organisms. No more circularities. Hope to support the editors of WIKI with this information. A non-circular definition of life and organisms is possible. Gerard Jagers Jager008 (talk) 13:38, 15 June 2011 (UTC)

Edit request from Iamthebestendof, 26 April 2011

Currently to Human knowledge life does not exist on any other planet other than Earth.

Iamthebestendof (talk) 14:46, 26 April 2011 (UTC)

Not done: please be more specific about what needs to be changed. — Bility (talk) 20:58, 26 April 2011 (UTC)

Weaseling in Early theories about life

"Some of the earliest theories of life were materialist" makes me want to insert the WHICH tag, but the main problem here is that current theories are also 'materialist', and the tone of this paragraph suggests all materialist theories are outdated. — Preceding unsigned comment added by 71.202.115.32 (talk) 00:18, 12 August 2011 (UTC)

Definition of Life - several considerations

Wikipedia defines a core hierarchy of more general and more specific (less general) concepts.

At the top of the hierarchy is probably the word "Concept". (And it expands down from there!)

Within that hierarchy there is also a network of connections between concepts (mostly references?).

As we rise up the hierarchy of meaning, the concepts become more general, and the labels become shorter. For example the concept of "Frog" is more general than the concept of "Tree Frog". So, when we define the concept of "Frog", we want to cover all types of frog, including tree frogs. Tree frogs themselves will be defined as a type of frog, and therefore lower in the Wikipedia concept hierarchy than the concept of "Frog". But "Frog" will be lower then "Amphibian".

Thus the phrase "Life" (which is very short) covers a very broad concept.

However in this article, the concept of "Life" in general (including "Artificial Life", etc), seems to have been suborned to the concepts of "Biological Life" and "Earthly Life", which I believe should probably be moved to their own subordinate locations in the Wikipedia conceptual hierarchy.

That way, I believe the definition of "Life" would be something like:

"A pattern that can repeatedly reproduce inexactly over a period of time <<leading to possibilities for Darwinian evolution or similar>> in a resource-available but resource-limited environment"

Please let's get back to the basic concepts here and take 'Biological' life and 'Earthly' life out to their own subordinate sections. — Preceding unsigned comment added by Jjalexand (talk • contribs) 16:19, 4 January 2012 (UTC)

Your definition is getting rather over broad. Under "pattern that reproduces itself" definition memes would be life. Organised structure that embodies the information to closely reproduce itself automatically would be closer to the mark, a physical structure being needed which memes do not possess. In terms of your concepts hierarchy, the term that would cover life and meme would be emergent complex information transmission system, or replicator if shorter term is more desirable. SkyMachine ⁽⁺⁺⁾ 19:44, 4 January 2012 (UTC)

Adaptation vs. Acclimation

In biology, the term adaptation refers to traits that arise from natural selection that make an organism more fit. Acclimation refers to an individual's ability to change homeostatically in response to the environment. "[Adaptation] The ability to change over a period of time in response to the environment" is ambiguous and it is not discernible whether an individual or population is being discussed. — Preceding unsigned comment added by 24.136.92.158 (talk) 08:33, 15 January 2012 (UTC)

Perhaps the word "Mutation" would be more appropriate, as it doesn't require the species to adapt to the environment, which it doesn't have to, else the countless species that failed to adapt to a changing environment, and went extinct, were NEVER alive. 118.209.12.148 (talk) 15:24, 29 January 2012 (UTC)

Nope, even beneficial mutations only introduce or extend the variability of traits that selection can act on. Species are not required to adapt. Populations adapt through the spread of traits (gene alleles, whether or not recently introduced by mutations) that increase the genetic fitness of individuals in the current environment. Populations that adapt to a changed environment tend to thrive in that environment. Populations that don't adapt to a changed environment tend to diminish in that environment. The causes of extinction for any species are complicated, and citing a "failure to adapt" tells us nothing about those causes. -- Donald Albury 20:49, 29 January 2012 (UTC)