Living systems

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Living systems are life forms (or, more colloquially known as living things) treated as a system. They are said to be open self-organizing and said to interact with their environment. These systems are maintained by flows of information, energy and matter. Multiple theories of living systems have been proposed. Such theories attempt to map general principles for how all living systems work.

Contents

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. [1] Such a general theory would arise out of the ecological and 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. [2]

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, interaction, behavior and 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 system. Below the level of living systems, he defines space and time, matter and energy, information and entropy, levels of organization, and physical and conceptual factors, and above living systems ecological, planetary and solar systems, galaxies, etc. [3] [4] [5] Miller's central thesis is that the multiple levels of living systems (cells, organs, organisms, groups, organizations, societies, supranational systems) are open systems composed of critical and mutually-dependent subsystems that process inputs, throughputs, and outputs of energy and information. [6] [7] [8] Seppänen (1998) says that Miller applied general systems theory on a broad scale to describe all aspects of living systems. [9] Bailey states that Miller's theory is perhaps the "most integrative" social systems theory, [10] 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 with information and order. It emphasizes both structure and process, as well as their interrelations. [11]

Lovelock's 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 physiology. [12] :10 The Gaia hypothesis, proposed in the 1960s by James Lovelock, suggests that life on Earth functions as a single organism that defines and maintains environmental conditions necessary for its survival. [13] [14]

Piast's self-maintainable information

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. A lather-like hierarchy of lifeness..png
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. [15] Cis-action is any action that has an impact on the initiator, and in chemical systems is known as the 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 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 UV radiation). Subsequently, if the entity is able to perform error-prone self-reproduction it gains the trait of evolution and belongs to a continuum of self-maintainable information - it becomes part of the living world in meaning of phenomenon but not yet a living 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 (a cell) or/and 2) maintaining a transmission process (for obligatory 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 dead or alive and requires the trait of functionality. [15] This approach provides a ladder-like 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. [15]

Morowitz's property of ecosystems

A systems view of life treats environmental fluxes and biological fluxes together as a "reciprocity of influence," [16] 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 ecological system rather than a single organism or species. [17] He argues that an ecosystemic definition of life is preferable to a strictly biochemical or physical one. Robert Ulanowicz (2009) highlights mutualism as the key to understand the systemic, order-generating behaviour of life and ecosystems. [18]

Rosen's complex systems biology

Robert Rosen devoted a large part of his career, from 1958 [19] 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. [20]

Complex systems biology is a field of science that studies the emergence of complexity in functional organisms from the viewpoint of dynamic systems theory. [21] The latter is also often called 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 of biological relations, as well as an algebraic topology of the functional organisation of living organisms in terms of their dynamic, complex networks of metabolic, genetic, and epigenetic processes and signalling pathways. [22] [23] 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. [24]

Bernstein, Byerly and Hopf's Darwinian dynamic

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 RNA molecules. The underlying order-generating process was concluded to be basically similar for both types of systems. [25] [26]

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 [27] 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. [28] [29] [30] [31] Life can be modelled as a network of inferior negative feedbacks of regulatory mechanisms subordinated to a superior positive feedback formed by the potential of expansion and reproduction. [32]

Kauffman's multi-agent system

Stuart Kauffman defines a living system as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle. [33] This definition is extended by the evolution of novel functions over time. [34]

Budisa, Kubyshkin and Schmidt's four pillars

Definition of cellular life according to Budisa, Kubyshkin and Schmidt Definition of cellular life NB.jpg
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) energy, (ii) metabolism, (iii) information and (iv) 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 (genetic information). Cells as self-sustaining units are parts of different populations that are involved in the unidirectional and irreversible open-ended process known as evolution. [35]

See also

Related Research Articles

Gaia philosophy is a broadly inclusive term for relating concepts about, humanity as an effect of the life of this planet.

<span class="mw-page-title-main">Life</span> Matter with biological processes

Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not, and is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction. Many philosophical definitions of living systems have been proposed, such as self-organizing systems. Viruses in particular make definition difficult as they replicate only in host cells. Life exists all over the Earth in air, water, and soil, with many ecosystems forming the biosphere. Some of these are harsh environments occupied only by extremophiles.

<span class="mw-page-title-main">Lynn Margulis</span> American evolutionary biologist (1938–2011)

Lynn Margulis was an American evolutionary biologist, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Margulis's name is as synonymous with symbiosis as Charles Darwin's is with evolution." In particular, Margulis transformed and fundamentally framed current understanding of the evolution of cells with nuclei – an event Ernst Mayr called "perhaps the most important and dramatic event in the history of life" – by proposing it to have been the result of symbiotic mergers of bacteria.

<span class="mw-page-title-main">Biophysics</span> Study of biological systems using methods from the physical sciences

Biophysics is an interdisciplinary science that applies approaches and methods traditionally used in physics to study biological phenomena. Biophysics covers all scales of biological organization, from molecular to organismic and populations. Biophysical research shares significant overlap with biochemistry, molecular biology, physical chemistry, physiology, nanotechnology, bioengineering, computational biology, biomechanics, developmental biology and systems biology.

<span class="mw-page-title-main">Superorganism</span> Group of synergistic organisms

A superorganism, or supraorganism, is a group of synergetically-interacting organisms of the same species. A community of synergetically-interacting organisms of different species is called a holobiont.

<span class="mw-page-title-main">Gaia hypothesis</span> Paradigm that living organisms interact with their surroundings in a self-regulating system

The Gaia hypothesis, also known as the Gaia theory, Gaia paradigm, or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.

<span class="mw-page-title-main">Autopoiesis</span> Systems concept which entails automatic reproduction and maintenance

The term autopoiesis refers to a system capable of producing and maintaining itself by creating its own parts. The term was introduced in the 1972 publication Autopoiesis and Cognition: The Realization of the Living by Chilean biologists Humberto Maturana and Francisco Varela to define the self-maintaining chemistry of living cells.

Robert Rosen was an American theoretical biologist and Professor of Biophysics at Dalhousie University.

<span class="mw-page-title-main">Systems biology</span> Computational and mathematical modeling of complex biological systems

Systems biology is the computational and mathematical analysis and modeling of complex biological systems. It is a biology-based interdisciplinary field of study that focuses on complex interactions within biological systems, using a holistic approach to biological research.

A complex adaptive system is a system that is complex in that it is a dynamic network of interactions, but the behavior of the ensemble may not be predictable according to the behavior of the components. It is adaptive in that the individual and collective behavior mutate and self-organize corresponding to the change-initiating micro-event or collection of events. It is a "complex macroscopic collection" of relatively "similar and partially connected micro-structures" formed in order to adapt to the changing environment and increase their survivability as a macro-structure. The Complex Adaptive Systems approach builds on replicator dynamics.

Teleonomy is the quality of apparent purposefulness and of goal-directedness of structures and functions in living organisms brought about by natural processes like natural selection. The term derives from two Greek words, τέλος, from τελε-, and νόμος nomos ("law"). Teleonomy is sometimes contrasted with teleology, where the latter is understood as a purposeful goal-directedness brought about through human or divine intention. Teleonomy is thought to derive from evolutionary history, adaptation for reproductive success, and/or the operation of a program. Teleonomy is related to programmatic or computational aspects of purpose.

Research concerning the relationship between the thermodynamic quantity entropy and both the origin and evolution of life began around the turn of the 20th century. In 1910, American historian Henry Adams printed and distributed to university libraries and history professors the small volume A Letter to American Teachers of History proposing a theory of history based on the second law of thermodynamics and on the principle of entropy.

The branches of science, also referred to as sciences, scientific fields or scientific disciplines, are commonly divided into three major groups:

<span class="mw-page-title-main">Organism</span> Any individual living being or physical living system

An organism is any biological living system that functions as an individual life form. All organisms are composed of cells. The idea of organism is based on the concept of minimal functional unit of life. Three traits have been proposed to play the main role in qualification as an organism:

An individual is that which exists as a distinct entity. Individuality is the state or quality of living as an individual; particularly of as a person unique from other people and possessing one's own needs or goals, rights and responsibilities. The concept of an individual features in diverse fields, including biology, law, and philosophy. Every individual contributes significantly to the growth of a civilization. Society is a multifaceted concept that is shaped and influenced by a wide range of elements, including human behaviors, attitudes, and ideas. The culture, morals, and beliefs of others as well as the general direction and trajectory of the society can all be influenced and shaped by an individual's activities.

<span class="mw-page-title-main">Artificial life</span> Field of study

Artificial life is a field of study wherein researchers examine systems related to natural life, its processes, and its evolution, through the use of simulations with computer models, robotics, and biochemistry. The discipline was named by Christopher Langton, an American theoretical biologist, in 1986. In 1987 Langton organized the first conference on the field, in Los Alamos, New Mexico. There are three main kinds of alife, named for their approaches: soft, from software; hard, from hardware; and wet, from biochemistry. Artificial life researchers study traditional biology by trying to recreate aspects of biological phenomena.

This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology, Glossary of environmental science and Glossary of scientific naming, or any of the organism-specific glossaries in Category:Glossaries of biology.

The internal measurement refers to the quantum measurement realized by the endo-observer. Quantum measurement represents the action of a measuring device on the measured system. When the measuring device is a part of measured system, the measurement proceeds internally in relation to the whole system. This theory was introduced by Koichiro Matsuno and developed by Yukio-Pegio Gunji. They further expanded the original ideas of Robert Rosen and Howard Pattee on the quantum measurement in living systems viewed as natural internal observers that belong to the same scale of the observed objects. According to Matsuno, the internal measurement is accompanied by the redistribution of probabilities that leave them entangled in accordance with the many-worlds interpretation of quantum mechanics by Everett. However, this form of quantum entanglement does not survive in the external measurement in which the mapping to real numbers takes place and the result is revealed in the classical time-space as the Copenhagen interpretation suggests. This means that the internal measurement concept unifies the alternative interpretations of quantum mechanics.

<span class="mw-page-title-main">Philosophy of ecology</span>

Philosophy of ecology is a concept under the philosophy of science, which is a subfield of philosophy. Its main concerns centre on the practice and application of ecology, its moral issues, and the intersectionality between the position of humans and other entities. This topic also overlaps with metaphysics, ontology, and epistemology, for example, as it attempts to answer metaphysical, epistemic and moral issues surrounding environmental ethics and public policy.

References

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Further reading