View source for Biology:Living systems

{{Short description|Multiple interactions and regulation of life forms with their environment}}
'''Living systems''' are life forms (or, more colloquially known as '''living things''') treated as a [[Philosophy:System|system]]. They are said to be [[Open system (systems theory)|open]] [[Physics:Self-organization|self-organizing]] and said to interact with their environment. These systems are maintained by flows of [[Information|information]], [[Physics:Energy flow (ecology)|energy]] and [[Physics:Matter|matter]]. Multiple theories of living systems have been proposed. Such theories attempt to map general principles for how all living systems work.

== Context ==

Some scientists have proposed in the last few decades that a general theory of living systems is required to explain the nature of life.<ref>{{Cite book |last1=Clealand |first1=Carol E. |last2=Chyba |first2=Christopher F. |chapter=Does 'Life' Have a Definition? |editor-last1=Woodruff |editor-first1=T. Sullivan |editor-last2=Baross |editor-first2=John |title=Planets and Life: The Emerging Science of Astrobiology |publisher=Cambridge University Press |date=8 October 2007 |quote=In the absence of such a theory, we are in a position analogous to that of a 16th-century investigator trying to define 'water' in the absence of molecular theory. [...] Without access to living things having a different historical origin, it is difficult and perhaps ultimately impossible to formulate an adequately general theory of the nature of living systems}}</ref> Such a general theory would arise out of the [[Earth:Ecology|ecological]] and [[Biology:Biology|biological sciences]] and attempt to map general principles for how all living systems work. Instead of examining phenomena by attempting to break things down into components, a general living systems theory explores phenomena in terms of dynamic patterns of the relationships of organisms with their environment.<ref>{{cite web |title=Patterns, Flows, and Interrelationship |url=http://www.mollyyoungbrown.com/systems_article.htm |access-date=27 June 2009 |first=Molly Young |last=Brown |date=2002 |url-status=dead |archive-url=https://web.archive.org/web/20090108122526/http://www.mollyyoungbrown.com/systems_article.htm |archive-date=8 January 2009}}</ref>

== Theories ==

=== Miller's open systems ===

James Grier Miller's living systems theory is a general theory about the existence of all living systems, their [[Structure|structure]], [[Biology:Biological interaction|interaction]], behavior and [[Biology:Developmental biology|development]], intended to formalize the concept of life. According to Miller's 1978 book ''Living Systems'', such a system must contain each of twenty "critical subsystems" defined by their functions. Miller considers living systems as a type of [[Philosophy:System|system]]. Below the level of living systems, he defines [[Space|space]] and [[Time|time]], [[Physics:Matter|matter]] and [[Physics:Energy|energy]], [[Information|information]] and [[Physics:Entropy|entropy]], levels of [[Organization:Organization|organization]], and physical and conceptual factors, and above living systems ecological, planetary and solar systems, galaxies, etc.<ref name="Miller 1978">{{cite book |isbn=978-0070420151 |title=Living Systems |last=Miller |first=James Grier |year=1978 |publisher=McGraw-Hill |place=New York}}</ref><ref name="Seppänen 1998">{{cite book |last=Seppänen |first=Jouko |year=1998 |chapter=Systems ideology in human and social sciences |editor1=Altmann, G. |editor2=Koch, W.A. |title=Systems: New paradigms for the human sciences |pages=180–302 |location=Berlin |publisher=Walter de Gruyter}}</ref><ref name="Járos 2000">{{cite journal | last=Járos | first=György | title=Living Systems Theory of James Grier Miller and teleonics | journal=Systems Research and Behavioral Science | publisher=Wiley | volume=17 | issue=3 | year=2000 | issn=1092-7026 | doi=10.1002/(sici)1099-1743(200005/06)17:3<289::aid-sres333>3.0.co;2-z | pages=289–300}}</ref> Miller's central thesis is that the multiple levels of living systems (cells, organs, organisms, groups, organizations, societies, supranational systems) are [[Open system (systems theory)|open systems]] composed of critical and mutually-dependent subsystems that process inputs, throughputs, and outputs of energy and information.<ref>(Miller, 1978, p. 1025)</ref><ref name="Parent 1996">{{cite web |last1=Parent |first1=Elaine |title=The Living Systems Theory  of James Grier Miller |url=https://web3.isss.org/primer2/PP1/asem14ep.html |website=The Primer Project |access-date=20 September 2023 |date=1996}}</ref><ref name="Primer">{{cite web |url=http://projects.isss.org/doku.php?id=the_earth_as_a_system |title=The Earth as a System |website=Primer project ISSS |access-date=20 September 2023}}</ref> Seppänen (1998) says that Miller applied general systems theory on a broad scale to describe all aspects of living systems.<ref>Seppänen 1998, pp. 197–198.</ref> Bailey states that Miller's theory is perhaps the "most integrative" social systems theory,<ref>Kenneth D. Bailey 2006, pp.292–296.</ref> clearly distinguishing between matter–energy-processing and information-processing, showing how social systems are linked to biological systems. LST analyzes the irregularities or "organizational pathologies" of systems functioning (e.g., system stress and strain, feedback irregularities, information–input overload). It explicates the role of entropy in social research while it equates [[Negentropy|negentropy]] with information and order. It emphasizes both structure and process, as well as their interrelations.<ref>Kenneth D. Bailey, 1994, pp. 209–210.</ref>

=== Lovelock's Gaia hypothesis ===

{{main|Astronomy:Gaia hypothesis}}

The idea that Earth is alive is found in philosophy and religion, but the first scientific discussion of it was by the Scottish geologist James Hutton. In 1785, he stated that Earth was a superorganism and that its proper study should be [[Biology:Physiology|physiology]].<ref name="Lovelock-1979">{{cite book |title=Gaia: A New Look at Life on Earth |date=1979 |publisher=Oxford University Press |isbn=978-0-19-286030-9 |first1=James |last1=Lovelock |url=https://archive.org/details/gaianewlookatlif00love_0 }}</ref>{{Rp|10}} The Gaia hypothesis, proposed in the 1960s by [[Biography:James Lovelock|James Lovelock]], suggests that life on Earth functions as a single organism that defines and maintains [[Earth:Natural environment|environmental]] conditions necessary for its survival.<ref name="Lovelock1965">{{Cite journal |last1=Lovelock |first1=J.E. |date=1965 |title=A physical basis for life detection experiments |journal=Nature |volume=207 |issue=7 |pages=568–570 |doi=10.1038/207568a0 |pmid=5883628 |bibcode=1965Natur.207..568L|s2cid=33821197 }}</ref><ref>{{cite web |first1=James |last1=Lovelock |author-link=James Lovelock |title=Geophysiology |website=Papers by James Lovelock |url=http://www.jameslovelock.org/page4.html#GEO |url-status=dead |archive-url=https://web.archive.org/web/20070506073502/http://www.jameslovelock.org/page4.html#GEO |archive-date=6 May 2007 |access-date=1 October 2009 }}</ref>

=== Piast's self-maintainable information ===

[[File:A lather-like hierarchy of lifeness..png|thumb|upright=2|According to the theory of self-maintainable information, entities can be ranked by how alive they are, gaining the ability to evolve and maintaining distinctness.]]

All living entities possess genetic information that maintains itself by processes called cis-actions.<ref name="Piast-2019">{{Cite journal |last=Piast |first=Radosław W. |date=June 2019 |title=Shannon's information, Bernal's biopoiesis and Bernoulli distribution as pillars for building a definition of life |url=https://linkinghub.elsevier.com/retrieve/pii/S0022519319301109 |journal=Journal of Theoretical Biology  |volume=470 |pages=101–107 |doi=10.1016/j.jtbi.2019.03.009 |pmid=30876803 |bibcode=2019JThBi.470..101P |s2cid=80625250 |access-date=1 January 2023 |archive-date=15 December 2019 |archive-url=https://web.archive.org/web/20191215051539/https://linkinghub.elsevier.com/retrieve/pii/S0022519319301109 |url-status=live }}</ref> [[Biology:Cis-action|Cis-action]] is any action that has an impact on the initiator, and in chemical systems is known as the [[Autocatalytic set|autocatalytic set]]. In living systems, all the cis-actions have generally a positive influence on the system as those with negative impact are eliminated by [[Biology:Natural selection|natural selection]]. Genetic information acts as an initiator, and it can maintain itself via a series of cis-actions like self-repair or self-production (the production of parts of the body to be distinguished from self-reproduction, which is a duplication of the entire entity). Various cis-actions give the entity additional traits to be considered alive. Self-maintainable information is a basic requirement - a level zero for gaining lifeness and it can be obtained by any cis-action like self-repair (like a gene coding a protein that fixes alteration to a nucleic acid caused by [[Physics:Ultraviolet|UV]] radiation). Subsequently, if the entity is able to perform error-prone self-reproduction it gains the trait of [[Biology:Evolution|evolution]] and belongs to a continuum of self-maintainable [[Information|information]] - it becomes part of the living world in meaning of [[Philosophy:Phenomenon|phenomenon]] but not yet a living [[Philosophy:Individual|individual]]. For this upgrade, the entity has to process the trait of distinctness, understood as an ability to define itself as a separate entity with its own fate. There are two possible ways of reaching distinctness: 1) maintaining an [[Open system (systems theory)|open-system]] (a [[Biology:Cell|cell]]) or/and 2) maintaining a transmission process (for obligatory [[Earth:Parasitism|parasites]]). Fulfiling any of these cis-actions raises the entity to a level of living individual - a distinct element of the self-maintainable information's continuum. The final level regards the state of the entity as [[Biology:Death|dead]] or alive and requires the trait of functionality.<ref name="Piast-2019" /> This approach provides a ladder-like [[Hierarchy|hierarchy]] of entities depending on their ability to maintain themselves, their evolvability, and their distinctness. It distinguishes between life as a phenomenon, a living individual, and an alive individual.<ref name="Piast-2019" />

=== Morowitz's property of ecosystems ===

A systems view of life treats environmental [[Physics:Flux|flux]]es and biological fluxes together as a "reciprocity of influence,"<ref>{{cite web |url=http://www.calresco.org/fiscus/esl.htm |title=The Ecosystemic Life Hypothesis |last=Fiscus |first=Daniel A. |date=April 2002 |publisher=Bulletin of the Ecological Society of America|archive-url=https://web.archive.org/web/20090806015449/http://www.calresco.org/fiscus/esl.htm|archive-date=6 August 2009|url-status=dead |access-date=28 August 2009}}</ref> and a reciprocal relation with environment is arguably as important for understanding life as it is for understanding ecosystems. As Harold J. Morowitz (1992) explains it, life is a property of an [[Earth:Ecosystem|ecological system]] rather than a single organism or species.<ref>{{cite book |last1=Morowitz |first1=Harold J. |date=1992 |title=Beginnings of cellular life: metabolism recapitulates biogenesis |publisher=Yale University Press |isbn=978-0-300-05483-5 |url={{GBurl|id=CmQDSHN_UrIC}} }}</ref> He argues that an ecosystemic definition of life is preferable to a strictly biochemical or physical one. [[Biography:Robert Ulanowicz|Robert Ulanowicz]] (2009) highlights mutualism as the key to understand the systemic, order-generating behaviour of life and ecosystems.<ref>{{cite book |first1=Robert W. |last1=Ulanowicz |first2=Robert E. |last2=Ulanowicz |title=A third window: natural life beyond Newton and Darwin |publisher=Templeton Foundation Press |date=2009 |isbn=978-1-59947-154-9 |url={{GBurl|id=gAQKAQAAMAAJ}} }}</ref>

=== Rosen's complex systems biology ===

{{main|Biology:Complex systems biology}}

[[Biography:Robert Rosen (theoretical biologist)|Robert Rosen]] devoted a large part of his career, from 1958<ref>{{cite journal |doi=10.1007/bf02478302 |title=A relational theory of biological systems |year=1958 |last=Rosen |first=Robert |journal=The Bulletin of Mathematical Biophysics |volume=20 |issue=3 |pages=245–260 }}</ref> onwards, to developing a comprehensive theory of life as a self-organizing complex system, "closed to efficient causation". He defined a system component as "a unit of organization; a part with a function, i.e., a definite relation between part and whole." He identified the "nonfractionability of components in an organism" as the fundamental difference between living systems and "biological machines." He summarised his views in his book ''Life Itself''.<ref>{{cite book |title=Life Itself: A Comprehensive Inquiry into the Nature, Origin, and Fabrication of Life |first=Rosen |last=Robert |date=1991 |isbn=978-0-231-07565-7 |publisher=Columbia University Press |place=New York}}</ref>

Complex systems biology is a field of science that studies the emergence of complexity in functional organisms from the viewpoint of dynamic systems theory.<ref>{{cite journal |last1=Baianu |first1=I.C. |date=2006 |title=Robert Rosen's Work and Complex Systems Biology |journal=Axiomathes |volume=16 |issue=1–2 |pages=25–34 |doi=10.1007/s10516-005-4204-z|s2cid=4673166 }}</ref> The latter is also often called [[Biology:Systems biology|systems biology]] and aims to understand the most fundamental aspects of life. A closely related approach, relational biology, is concerned mainly with understanding life processes in terms of the most important relations, and categories of such relations among the essential functional components of organisms; for multicellular organisms, this has been defined as "categorical biology", or a model representation of organisms as a [[Category theory|category theory]] of biological relations, as well as an [[Algebraic topology|algebraic topology]] of the functional organisation of living organisms in terms of their dynamic, complex [[Biology:Biological network|networks]] of metabolic, genetic, and epigenetic processes and signalling pathways.<ref>* {{cite journal |last1=Rosen |first1=Robert |date=1958a |title=A Relational Theory of Biological Systems |journal=Bulletin of Mathematical Biophysics |volume=20 |issue=3 |pages=245–260 |doi=10.1007/bf02478302}}</ref><ref>* {{cite journal |last1=Rosen |first1=R. |date=1958b |title=The Representation of Biological Systems from the Standpoint of the Theory of Categories |journal=Bulletin of Mathematical Biophysics |volume=20 |issue=4 |pages=317–341 |doi=10.1007/bf02477890}}</ref> Related approaches focus on the interdependence of constraints, where constraints can be either molecular, such as enzymes, or macroscopic, such as the geometry of a bone or of the vascular system.<ref>{{Cite journal |last1=Montévil |first1=Maël |last2=Mossio |first2=Matteo |date=7 May 2015 |title=Biological organisation as closure of constraints |url=https://www.academia.edu/11705712 |journal=Journal of Theoretical Biology |volume=372 |pages=179–191 |doi=10.1016/j.jtbi.2015.02.029 |pmid=25752259 |bibcode=2015JThBi.372..179M |url-status=live |archive-url=https://web.archive.org/web/20171117143806/http://www.academia.edu/11705712/Biological_organisation_as_closure_of_constraints |archive-date=17 November 2017 |citeseerx=10.1.1.701.3373 |s2cid=4654439 }}</ref>

=== Bernstein, Byerly and Hopf's Darwinian dynamic ===

{{main|Biology:Evolutionary dynamics}}

Harris Bernstein and colleagues argued in 1983 that the evolution of order in living systems and certain physical systems obeys a common fundamental principle termed the Darwinian dynamic. This was formulated by first considering how macroscopic order is generated in a simple non-biological system far from thermodynamic equilibrium, and then extending consideration to short, replicating [[Biology:RNA|RNA]] molecules. The underlying order-generating process was concluded to be basically similar for both types of systems.<ref name="Bernstein Byerly Hopf 1983">{{cite journal |last1=Bernstein |first1=Harris |first2=Henry C. |last2=Byerly |first3=Frederick A. |last3=Hopf |first4=Richard A. |last4=Michod |first5=G. Krishna |last5=Vemulapalli |title=The Darwinian Dynamic |volume=58 |issue=2 |date=June 1983 |journal=The Quarterly Review of Biology |jstor=2828805 |doi=10.1086/413216 |page=185 |s2cid=83956410 }}</ref><ref name="Michod 2000">{{Cite book |title=Darwinian Dynamics: Evolutionary Transitions in Fitness and Individuality |last=Michod |first=Richard E. |publisher=Princeton University Press |year=2000 |isbn=978-0-691-05011-9 |location=Princeton }}</ref>

=== Gerard Jagers' operator theory ===

Gerard Jagers' operator theory proposes that life is a general term for the presence of the typical closures found in organisms; the typical closures are a membrane and an autocatalytic set in the cell<ref>{{Cite book |title=The Pursuit of Complexity: The Utility of Biodiversity from an Evolutionary Perspective |last=Jagers |first=Gerard |publisher=KNNV Publishing |year=2012 |isbn=978-90-5011-443-1 |pages=27–29, 87–88, 94–96}}</ref> and that an organism is any system with an organisation that complies with an operator type that is at least as complex as the cell.<ref>{{cite journal | doi= 10.1007/s10699-010-9177-8| title= Towards a Hierarchical Definition of Life, the Organism, and Death| year= 2010 |last1=Jagers Op Akkerhuis | first1=Gerard A. J. M. |journal=Foundations of Science| volume= 15| issue= 3 | pages=245–262| s2cid=195282529}}</ref><ref>{{cite journal | doi=10.1007/s10699-010-9209-4 | title=Explaining the Origin of Life is not Enough for a Definition of Life | year=2011 | last1=Jagers Op Akkerhuis | first1=Gerard | journal=Foundations of Science | volume=16 | issue=4 | pages=327–329 | s2cid=195284978 }}</ref><ref>{{cite journal | doi=10.1080/073911012010525006 | title= The Role of Logic and Insight in the Search for a Definition of Life| year=2012 | last1=Jagers Op Akkerhuis| first1=Gerard A. J. M. | journal=Journal of Biomolecular Structure and Dynamics | volume=29 | issue=4 | pages= 619–620 | pmid= 22208258| s2cid=35426048 | url=https://library.wur.nl/WebQuery/wurpubs/441202| access-date= 16 April 2021 | archive-date=16 April 2021 | archive-url=https://web.archive.org/web/20210416121541/https://library.wur.nl/WebQuery/wurpubs/441202| url-status= live| doi-access= free}}</ref><ref>{{Cite book |title=Integral Biomathics |last=Jagers |first=Gerald |publisher=Springer |year=2012 |isbn=978-3-642-28110-5|editor-last=Ehresmann|editor-first=Andree C. |chapter=Contributions of the Operator Hierarchy to the Field of Biologically Driven Mathematics and Computation |editor-last2=Simeonov|editor-first2=Plamen L.|editor-last3=Smith|editor-first3=Leslie S. }}</ref> Life can be modelled as a network of inferior [[Negative feedback|negative feedback]]s of regulatory mechanisms subordinated to a superior [[Positive feedback|positive feedback]] formed by the potential of expansion and reproduction.<ref>{{cite journal |last1=Korzeniewski |first1=Bernard |title=Cybernetic formulation of the definition of life |journal=Journal of Theoretical Biology |date=7 April 2001 |volume=209 |issue=3 |pages=275–286 |pmid=11312589 |doi=10.1006/jtbi.2001.2262 |bibcode=2001JThBi.209..275K }}</ref>

=== Kauffman's multi-agent system ===

[[Biography:Stuart Kauffman|Stuart Kauffman]] defines a living system as an [[Autonomous agent|autonomous agent]] or a [[Multi-agent system|multi-agent system]] capable of reproducing itself or themselves, and of completing at least one [[Physics:Thermodynamic cycle|thermodynamic work cycle]].<ref>{{Cite book |first1=Stuart |last1=Kaufmann |title=Science and Ultimate Reality |date=2004 |chapter=Autonomous agents |editor1-first=John D. |editor1-last=Barrow |editor2-last=Davies |editor3-first=C.L. |editor3-last=Harper, Jr. |pages=654–666 |doi=10.1017/CBO9780511814990.032 |isbn=978-0-521-83113-0 |chapter-url={{GBurl|id=K_OfC0Pte_8C|p=654}} |editor2-first=P.C.W. }}</ref> This definition is extended by the evolution of novel functions over time.<ref>{{Cite book |last1=Longo |first1=Giuseppe |last2=Montévil |first2=Maël |last3=Kauffman |first3=Stuart |title=Proceedings of the 14th annual conference companion on Genetic and evolutionary computation |chapter=No entailing laws, but enablement in the evolution of the biosphere |date=1 January 2012 |url=https://www.academia.edu/11720588 |series=GECCO '12 |pages=1379–1392 |doi=10.1145/2330784.2330946 |isbn=978-1-4503-1178-6 |url-status=live |archive-url=https://web.archive.org/web/20170511103757/http://www.academia.edu/11720588/No_entailing_laws_but_enablement_in_the_evolution_of_the_biosphere |archive-date=11 May 2017 |arxiv=1201.2069 |citeseerx=10.1.1.701.3838 |bibcode=2012arXiv1201.2069L |s2cid=15609415 }}</ref>

=== Budisa, Kubyshkin and Schmidt's four pillars ===

[[File:Definition of cellular life NB.jpg|thumb|upright=1.5|Definition of cellular life according to Budisa, Kubyshkin and Schmidt]]

Budisa, Kubyshkin and Schmidt defined cellular life as an organizational unit resting on four pillars/cornerstones: (i) [[Physics:Energy#Biology|energy]], (ii) [[Biology:Metabolism|metabolism]], (iii) [[Information|information]] and (iv) [[Biology:Body plan|form]]. This system is able to regulate and control metabolism and energy supply and contains at least one subsystem that functions as an information carrier ([[Biology:Nucleic acid sequence|genetic information]]). [[Biology:Cell|Cells]] as self-sustaining units are parts of different [[Social:Population|population]]s that are involved in the unidirectional and irreversible open-ended process known as [[Biology:Evolution|evolution]].<ref>{{cite journal |last1=Budisa |first1=Nediljko |last2=Kubyshkin |first2=Vladimir |last3=Schmidt |first3=Markus |title=Xenobiology: A Journey towards Parallel Life Forms |journal=ChemBioChem |date=22 April 2020|volume=21 |issue=16 |pages=2228–2231 |doi=10.1002/cbic.202000141 |pmid=32323410 |doi-access=free}}</ref>

== See also ==

* {{annotated link|Artificial life}}
* {{annotated link|Autopoiesis}}
* {{annotated link|Earth system science}}
* {{annotated link|Astronomy:Extraterrestrial life}}
* {{annotated link|Philosophy:Information metabolism}}
* {{annotated link|Astronomy:Spome}}
* {{annotated link|Biology:Systems biology}}
* {{annotated link|Systems theory}}

== References ==

{{reflist|30em}}

== Further reading ==

* Kenneth D. Bailey, (1994). ''Sociology and the new systems theory: Toward a theoretical synthesis''. Albany, NY: SUNY Press.
* Kenneth D. Bailey (2006). Living systems theory and social entropy theory. ''Systems Research and Behavioral Science, 22'', 291–300.
* James Grier Miller, (1978). ''Living systems.'' New York: McGraw-Hill. {{ISBN|0-87081-363-3}}
* Miller, J.L., & Miller, J.G. (1992). Greater than the sum of its parts: Subsystems which process both matter-energy and information. ''Behavioral Science, 37'', 1–38.
* Humberto Maturana (1978), "[http://www.enolagaia.com/M78BoL.html Biology of language: The epistemology of reality]," in Miller, George A., and Elizabeth Lenneberg (eds.), ''Psychology and Biology of Language and Thought: Essays in Honor of Eric Lenneberg''. Academic Press: 27-63.
* Jouko Seppänen, (1998). Systems ideology in human and social sciences. In G. Altmann & W.A. Koch (Eds.), ''Systems: New paradigms for the human sciences'' (pp.&nbsp;180–302). Berlin: Walter de Gruyter.
* James R. Simms (1999). ''Principles of Quantitative Living Systems Science''. Dordrecht: Kluwer Academic. {{ISBN|0-306-45979-5}}

== External links ==

* [http://projects.isss.org/doku.php?id=living_systems_theory The Living Systems Theory Of James Grier Miller]
* [http://www.panarchy.org/miller/livingsystems.html James Grier Miller, Living Systems] The Basic Concepts (1978)


[[Category:Systems biology]]
[[Category:Systems theory]]
[[Category:Biological systems]]

{{Sourceattribution|Living systems}}