organism

The term "organism" (from the Ancient Greek {{Wikt-lang|grc|ὀργανισμός}}, derived from {{grc-transl|ὄργανον}}, meaning {{gloss|instrument, implement, tool}}, {{gloss|organ of sense}}, or {{gloss|apprehension}}){{LSJ|o)/rganon|ὄργανον|ref}} first appeared in the English language in the 1660s with the now-obsolete meaning of an organic structure or organization.{{cite web |title=organism (n.) |url=https://www.etymonline.com/word/organism |publisher=Online Etymology Dictionary |access-date=11 April 2024}} It is related to the verb "organize". In his 1790 Critique of Judgment, Immanuel Kant defined an organism as "both an organized and a self-organizing being".{{cite book |last=Kant |first=Immanuel |author-link=Immanuel Kant |title=Critique of Judgment |year=1790 |publisher=Lagarde und Friederich |at=§65 5:374}}{{cite journal |last=Huneman |first=Philippe |title=Kant's Concept of Organism Revisited: A Framework for a Possible Synthesis between Developmentalism and Adaptationism? |journal=The Monist |volume=100 |issue=3 |year=2017 |pages=373–390 |doi=10.1093/monist/onx016 |jstor=26370801}}

File:Basilikumwurzling.jpg plant cutting is however developing new adventitious roots from a small bit of stem, forming a new plant.]]

Among the criteria that have been proposed for being an organism are:

• autonomous reproduction, growth, and metabolism
• noncompartmentability – structure cannot be divided without losing functionality.{{Cite journal |last=Rosen |first=Robert |date=September 1958 |title=A relational theory of biological systems |url=http://link.springer.com/10.1007/BF02478302 |journal=The Bulletin of Mathematical Biophysics |volume=20 |issue=3 |pages=245–260 |doi=10.1007/BF02478302 |issn=0007-4985}} Richard Dawkins stated this as "the quality of being sufficiently heterogeneous in form to be rendered non-functional if cut in half". However, many organisms can be cut into pieces which then grow into whole organisms.
• individuality – the entity has simultaneous holdings of genetic uniqueness, genetic homogeneity and autonomy{{Cite journal |last=Santelices |first=Bernabé |date=April 1999 |title=How many kinds of individual are there? |url=https://linkinghub.elsevier.com/retrieve/pii/S0169534798015195 |journal=Trends in Ecology & Evolution |volume=14 |issue=4 |pages=152–155 |doi=10.1016/S0169-5347(98)01519-5 |pmid=10322523 }}
• an immune response, separating self from foreign{{cite journal |last=Pradeu |first=T. |title=What is an organism? An immunological answer |journal=History and Philosophy of the Life Sciences |volume=32 |issue=2–3 |pages=247–267 |year=2010 |pmid=21162370 }}
• "anti-entropy", the ability to maintain order, a concept first proposed by Erwin Schrödinger;{{cite journal |last1=Bailly |first1=Francis |last2=Longo |first2=Giuseppe |title=Biological Organization and Anti-entropy |journal=Journal of Biological Systems |volume=17 |issue=1 |date=2009 |issn=0218-3390 |doi=10.1142/S0218339009002715 |pages=63–96 |url=https://www.researchgate.net/publication/247697945}} or in another form, that Claude Shannon's information theory can be used to identify organisms as capable of self-maintaining their information content{{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 }}

Other scientists think that the concept of the organism is inadequate in biology;{{cite journal |last=Bateson |first=Patrick |title=The return of the whole organism |journal=Journal of Biosciences |volume=30 |issue=1 |pages=31–39 |date=February 2005 |pmid=15824439 |doi=10.1007/BF02705148 |s2cid=26656790 }}

that the concept of individuality is problematic;{{Cite journal |last=Clarke |first=E. |title=The problem of biological individuality |journal=Biological Theory |volume=5 |issue=4 |pages=312–325 |year=2010 |doi=10.1162/BIOT_a_00068 |s2cid=28501709 }}

and from a philosophical point of view, question whether such a definition is necessary.{{cite journal |last1=Pepper |first1=J.W. |last2=Herron |first2=M.D. |title=Does biology need an organism concept? |journal=Biological Reviews of the Cambridge Philosophical Society |volume=83 |issue=4 |pages=621–627 |date=November 2008 |pmid=18947335 |doi=10.1111/j.1469-185X.2008.00057.x |s2cid=4942890 }}{{Cite journal |last=Wilson |first=R. |title=The biological notion of individual |journal=Stanford Encyclopedia of Philosophy |date=2007}}{{Cite journal |pages=301–311 |last=Wilson |first=Jack A. |title=Ontological butchery: organism concepts and biological generalizations |journal=Philosophy of Science |date=2000 |jstor=188676 |volume=67 |doi=10.1086/392827 |s2cid=84168536 }}

Problematic cases include colonial organisms: for instance, a colony of eusocial insects fulfills criteria such as adaptive organisation and germ-soma specialisation.{{cite journal |last1=Folse |first1=H.J., III |last2=Roughgarden |first2=J. |title=What is an individual organism? A multilevel selection perspective |journal=The Quarterly Review of Biology |volume=85 |issue=4 |pages=447–472 |date=December 2010 |pmid=21243964 |doi=10.1086/656905 |s2cid=19816447 }} If so, the same argument, or a criterion of high co-operation and low conflict, would include some mutualistic (e.g. lichens) and sexual partnerships (e.g. anglerfish) as organisms.{{cite journal |last1=Queller |first1=David C. |last2=Strassmann |first2=Joan E. |title=Beyond society: the evolution of organismality |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |volume=364 |issue=1533 |pages=3143–3155 |date=November 2009 |pmid=19805423 |pmc=2781869 |doi=10.1098/rstb.2009.0095 }} If group selection occurs, then a group could be viewed as a superorganism, optimized by group adaptation.{{cite journal |last1=Gardner |first1=A. |last2=Grafen |first2=A. |title=Capturing the superorganism: a formal theory of group adaptation |journal=Journal of Evolutionary Biology |volume=22 |issue=4 |pages=659–671 |date=April 2009 |pmid=19210588 |doi=10.1111/j.1420-9101.2008.01681.x |s2cid=8413751 |doi-access=free }}

Another view is that attributes like autonomy, genetic homogeneity and genetic uniqueness should be examined separately, rather than requiring that an organism possess all of them. On this view, there are multiple dimensions to biological individuality, resulting in several types of organism.{{cite journal |last=Santelices |first=B. |title=How many kinds of individual are there? |journal=Trends in Ecology & Evolution |volume=14 |issue=4 |pages=152–155 |date=April 1999 |pmid=10322523 |doi=10.1016/s0169-5347(98)01519-5 }}

File:Lichen cross section – heteromeric thallus unlabelled.svg consists of a body formed mainly by fungi, with unicellular algae or cyanobacteria (green) interspersed within the structure, and a bacterial microbiome. The species are mutually interdependent, like cells within a multicellular organism.]]

Differing levels of biological organisation give rise to potentially different understandings of the nature of organisms. A unicellular organism is a microorganism such as a protist, bacterium, or archaean, composed of a single cell, which may contain functional structures called organelles.{{cite book |last=Hine |first=R.S. |title=A Dictionary of Biology |year=2008 |publisher=Oxford University Press |location=Oxford |isbn=978-0-19-920462-5 |page=461 |edition=6th}} A multicellular organism such as an animal, plant, fungus, or alga is composed of many cells, often specialised. A colonial organism such as a siphonophore is a being which functions as an individual but is composed of communicating individuals. A superorganism is a colony, such as of ants, consisting of many individuals working together as a single functional or social unit.{{cite book |last=Kelly |first=Kevin |title=Out of control: the new biology of machines, social systems and the economic world |publisher=Addison-Wesley |location=Boston |year=1994 |pages=[https://archive.org/details/outofcontrolnewb00kell/page/98 98] |isbn=978-0-201-48340-6 |url-access=registration |url=https://archive.org/details/outofcontrolnewb00kell}} A mutualism is a partnership of two or more species which each provide some of the needs of the other. A lichen consists of fungi and algae or cyanobacteria, with a bacterial microbiome; together, they are able to flourish as a kind of organism, the components having different functions, in habitats such as dry rocks where neither could grow alone.{{cite journal |last1=Lücking |first1=Robert |last2=Leavitt |first2=Steven D. |last3=Hawksworth |first3=David L. |title=Species in lichen-forming fungi: balancing between conceptual and practical considerations, and between phenotype and phylogenomics |journal=Fungal Diversity |volume=109 |issue=1 |date=2021 |doi=10.1007/s13225-021-00477-7 |pages=99–154|doi-access=free }} The evolutionary biologists David Queller and Joan Strassmann state that "organismality" has evolved socially, as groups of simpler units (from cells upwards) came to cooperate without conflicts. They propose that cooperation should be used as the "defining trait" of an organism.

{|class="wikitable plainrowheaders" style="margin: 1em auto;"

|+ Queller and Strassmann's view of organisms as cooperating entities at differing levels of biological organisation

|-

! scope="col" | Level

! scope="col" | Example

! scope="col" | Composition

! scope="col" | Metabolism,
growth,
reproduction

! scope="col" | Co-operation

|-

! scope="row" | Virus

| Tobacco mosaic virus || Nucleic acid, protein || No || No metabolism, so not living, not an organism, say many biologists; but they evolve, their genes collaborating to manipulate the host

|-

! scope="row" | Unicellular organism

| Paramecium || One cell, with organelles e.g. cilia for specific functions || Yes || Inter-cellular (inter-organismal) signalling

|-

! scope="row" | Swarming protistan

| Dictyostelium (cellular slime mould) || Unicellular amoebae || Yes || Free-living unicellular amoebae for most of lifetime; swarm and aggregate to a multicellular slug, cells specialising to form a dead stalk and a fruiting body

|-

! scope="row" | Multicellular organism

| Mushroom-forming fungus || Cells, grouped into organs for specific functions (e.g. reproduction) || Yes || Cell specialisation, communication

|-

! scope="row" | Permanent sexual partnership

| Anglerfish || Male and female permanently fastened together || Yes || Male provides male gametes; female provides all other functions

|-

! scope="row" | Mutualism

| Lichen || Organisms of different species || Yes || Fungus provides structure, absorbs water and minerals; alga photosynthesises

|-

! scope="row" | Joined colony

| Siphonophore || Zooids joined together || Yes || Organism specialisation; inter-organism signalling

|-

! scope="row" | Superorganism

| Ant colony || Individuals living together || Yes || Organism specialisation (many ants do not reproduce); inter-organism signalling

|}

Samuel Díaz‐Muñoz and colleagues (2016) accept Queller and Strassmann's view that organismality can be measured wholly by degrees of cooperation and of conflict. They state that this situates organisms in evolutionary time, so that organismality is context dependent. They suggest that highly integrated life forms, which are not context dependent, may evolve through context-dependent stages towards complete unification.{{cite journal |last1=Díaz-Muñoz |first1=Samuel L. |last2=Boddy |first2=Amy M. |last3=Dantas |first3=Gautam |last4=Waters |first4=Christopher M. |last5=Bronstein |first5=Judith L. |title=Contextual organismality: Beyond pattern to process in the emergence of organisms |journal=Evolution |volume=70 |issue=12 |year=2016 |issn=0014-3820 |pmid=27704542 |pmc=5132100 |doi=10.1111/evo.13078 |pages=2669–2677}}

{{main|Virus}}

File:TMV structure simple.png is not a cell; it contains only its genetic material, and a protein coat.]]

Viruses are not typically considered to be organisms, because they are incapable of autonomous reproduction, growth, metabolism, or homeostasis. Although viruses have a few enzymes and molecules like those in living organisms, they have no metabolism of their own; they cannot synthesize the organic compounds from which they are formed. In this sense, they are similar to inanimate matter.{{cite journal |last1=Moreira |first1=D. |last2=López-García |first2=P.N. |title=Ten reasons to exclude viruses from the tree of life |journal=Nature Reviews Microbiology |volume=7 |issue=4 |pages=306–311 |date=April 2009 |pmid=19270719 |doi=10.1038/nrmicro2108 |s2cid=3907750 }} Viruses have their own genes, and they evolve. Thus, an argument that viruses should be classed as living organisms is their ability to undergo evolution and replicate through self-assembly. However, some scientists argue that viruses neither evolve nor self-reproduce. Instead, viruses are evolved by their host cells, meaning that there was co-evolution of viruses and host cells. If host cells did not exist, viral evolution would be impossible. As for reproduction, viruses rely on hosts' machinery to replicate. The discovery of viruses with genes coding for energy metabolism and protein synthesis fuelled the debate about whether viruses are living organisms, but the genes have a cellular origin. Most likely, they were acquired through horizontal gene transfer from viral hosts.

{|class="wikitable plainrowheaders" style="margin: 1em auto;"

|+ Comparison of cellular organisms and viruses

|-

! scope="col" | Capability

! scope="col" | Cellular organism

! scope="col" | Virus

|-

! scope="row" | Metabolism

| Yes

| No, rely entirely on host cell

|-

! scope="row" | Growth

| Yes

| No, just self-assembly

|-

! scope="row" | Reproduction

| Yes

| No, rely entirely on host cell

|-

! scope="row" | Store genetic information about themselves

| DNA

| DNA or RNA

|-

! scope="row" | Able to evolve

| Yes: mutation, recombination, natural selection

| Yes: high mutation rate, natural selection

|}

There is an argument for viewing viruses as cellular organisms. Some researchers perceive viruses not as virions alone, which they believe are just spores of an organism, but as a virocell - an ontologically mature viral organism that has cellular structure.{{Cite journal |last=Forterre |first=Patrick |date=2012-10-04 |title=The virocell concept and environmental microbiology |url=https://doi.org/10.1038/ismej.2012.110 |journal=The ISME Journal |volume=7 |issue=2 |pages=233–236 |doi=10.1038/ismej.2012.110 |issn=1751-7362 |pmc=3554396 |pmid=23038175}} Such virus is a result of infection of a cell and shows all major physiological properties of other organisms: metabolism, growth, and reproduction, therefore, life in its effective presence.{{cite journal |last=Bandea |first=Claudiu I. |title=A new theory on the origin and the nature of viruses |journal=Journal of Theoretical Biology |volume=105 |issue=4 |date=1983 |doi=10.1016/0022-5193(83)90221-7 |pages=591–602|pmid=6672474 |bibcode=1983JThBi.105..591B }}

The RNA world is a hypothetical stage in the evolutionary history of life on Earth during which self-replicating RNA molecules reproduced before the evolution of DNA and proteins.Johnson, Mark (9 March 2024). "'Monumental' experiment suggests how life on Earth may have started". The Washington Post. Archived from the original on 9 March 2024. Retrieved 10 March 2024 According to this hypothesis "organisms" emerged when RNA chains began to self-replicate, initiating the three mechanisms of Darwinian selection: heritability, variation of type and differential reproductive output. The fitness of an RNA replicator (its per capita rate of increase) would presumably have been a function of its intrinsic adaptive capacities, determined by its nucleotide sequence, and the availability of external resources.Bernstein, H., Byerly, H. C., Hopf, F. A., Michod, R. A., & Vemulapalli, G. K. (1983). The Darwinian Dynamic. The Quarterly Review of Biology, 58(2), 185–207. http://www.jstor.org/stable/2828805Michod, R.E. Darwinian Dynamics: Evolutionary transitions in fitness and individuality. Copyright 1999 Princeton University Press, Princeton, New Jersey ISBN 0-691-02699-8 The three primary adaptive capacities of these early "organisms" may have been: (1) replication with moderate fidelity, giving rise to both heritability while allowing variation of type, (2) resistance to decay, and (3) acquisition of and processing of resources The capacities of these "organisms" would have functioned by means of the folded configurations of the RNA replicators resulting from their nucleotide sequences.

File:Apolemia sp.jpg, a colonial siphonophore that functions as a single individual]]

The philosopher Jack A. Wilson examines some boundary cases to demonstrate that the concept of organism is not sharply defined. In his view, sponges, lichens, siphonophores, slime moulds, and eusocial colonies such as those of ants or naked molerats, all lie in the boundary zone between being definite colonies and definite organisms (or superorganisms).

{| class="wikitable plainrowheaders" style="margin: 1em auto;"

|+ Jack A. Wilson's analysis of the similar organism-like nature of siphonophores and jellyfish

|-

! scope="col" | Function

! scope="col" | Colonial siphonophore

! scope="col" | Jellyfish

|-

! scope="row" | Buoyancy

| Top of colony is gas-filled || Jelly

|-

! scope="row" | Propulsion

| Nectophores co-ordinate to pump water || Body pulsates to pump water

|-

! scope="row" | Feeding

| Palpons and gastrozooids ingest prey, feed other zooids || Tentacles trap prey, pass it to mouth

|-

! scope="row" | Functional structure

| Single functional individual || Single functional individual

|-

! scope="row" | Composition

| Many zooids, possibly individuals || Many cells

|}

{{Clear}}

File:Insect cyborg.jpg ]]

Scientists and bio-engineers are experimenting with different types of synthetic organism, from chimaeras composed of cells from two or more species, cyborgs including electromechanical limbs, hybrots containing both electronic and biological elements, and other combinations of systems that have variously evolved and been designed.{{cite journal |last1=Clawson |first1=Wesley P. |last2=Levin |first2=Michael |title=Endless forms most beautiful 2.0: teleonomy and the bioengineering of chimaeric and synthetic organisms |journal=Biological Journal of the Linnean Society |volume=138 |issue=1 |date=2023-01-01 |issn=0024-4066 |doi=10.1093/biolinnean/blac116 |pages=141|doi-access=free }}

An evolved organism takes its form by the partially understood mechanisms of evolutionary developmental biology, in which the genome directs an elaborated series of interactions to produce successively more elaborate structures. The existence of chimaeras and hybrids demonstrates that these mechanisms are "intelligently" robust in the face of radically altered circumstances at all levels from molecular to organismal.

Synthetic organisms already take diverse forms, and their diversity will increase. What they all have in common is a teleonomic or goal-seeking behaviour that enables them to correct errors of many kinds so as to achieve whatever result they are designed for. Such behaviour is reminiscent of intelligent action by organisms; intelligence is seen as an embodied form of cognition.

{{reflist}}

• {{cite web |work=Tree of Life Web Project |url=http://tolweb.org/tree/phylogeny.html |title=The Tree of Life }}
• {{cite web |url=http://www.species2000.org/ |work=Species 2000 |title=Indexing the world's known species }}

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