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Living systems are open self-organizing living things that interact with their environment. These systems are maintained by flows of information, energy and matter. Some scientists have proposed in the last few decades that a general living systems theory is required to explain the nature of life.〔 Cleland and Chyba wrote a chapter in Planets and Life: "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".〕 Such a general theory, arising out of the ecological and biological sciences, attempts 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. ==Theory== Living systems theory is a general theory about the existence of all living systems, their structure, interaction, behavior and development. This work is created by James Grier Miller, which was intended to formalize the concept of life. According to Miller's original conception as spelled out in his magnum opus ''Living Systems'', a "living system" must contain each of twenty "critical subsystems", which are defined by their functions and visible in numerous systems, from simple cells to organisms, countries, and societies. In ''Living Systems'' Miller provides a detailed look at a number of systems in order of increasing size, and identifies his subsystems in each. Miller considers living systems as a subset of all systems. 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.〔Seppänen, 1998, p. 198〕 Living systems according to Parent (1996) are by definition "open self-organizing systems that have the special characteristics of life and interact with their environment. This takes place by means of information and material-energy exchanges. Living systems can be as simple as a single cell or as complex as a supranational organization such as the European Union. Regardless of their complexity, they each depend upon the same essential twenty subsystems (or processes) in order to survive and to continue the propagation of their species or types beyond a single generation".〔Elaine Parent, (''The Living Systems Theory of James Grier Miller'' ), Primer project ISSS, 1996.〕 Miller said that systems exist at eight "nested" hierarchical levels: cell, organ, organism, group, organization, community, society, and supranational system. At each level, a system invariably comprises twenty critical subsystems, which process matter–energy or information except for the first two, which process both matter–energy and information: reproducer and boundary. The processors of matter–energy are: * ingestor, distributor, converter, producer, storage, extruder, motor, supporter The processors of information are * input transducer, internal transducer, channel and net, timer (added later), decoder, associator, memory, decider, encoder, output transducer. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「living systems」の詳細全文を読む スポンサード リンク
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