Survival

Homeostasis, from the Greek words for "same" and "steady," refers to any process that living things use to actively maintain fairly stable conditions necessary for survival. The term was coined in 1930 by the physician Walter Cannon. His book, The Wisdom of the Body, describes how the human body maintains steady levels of temperature and other vital conditions such as the water, salt, sugar, protein, fat, calcium and oxygen contents of the blood. Similar processes dynamically maintain steady-state conditions in the Earth's environment.

Homeostasis has found useful applications in the social sciences. It refers to how a person under conflicting stresses and motivations can maintain a stable psychological condition. A society homeostatically maintains its stability despite competing political, economic and cultural factors. A good example is the law of supply and demand, whereby the interaction of supply and demand keeps market prices reasonably stable.

Homeostatic ideas are shared by the science of cybernetics (from the Greek for "steersman"), defined in 1948 by the mathematician Norbert Wiener as "the entire field of control and communication theory, whether in the machine or in the animal." Cybernetic systems can "remember" disturbances and thus are used in computer science to store and transmit information. Negative feedback is a central homeostatic and cybernetic concept, referring to how an organism or system automatically opposes any change imposed upon it.

For example, the human body uses a number of processes to control its temperature, keeping it close to an average value or norm of 98.6 degrees Fahrenheit. One of the most obvious physical responses to overheating is sweating, which cools the body by making more moisture on the skin available for evaporation. On the other hand, the body reduces heat-loss in cold surroundings by sweating less and reducing blood circulation to the skin. Thus, any change that either raises or lowers the normal temperature automatically triggers a counteracting, opposite or negative feedback. ...

Ashby's Law of Requisite Variety ("only variety can destroy variety") makes clear in the simplest terms that if a system is to survive in a changing environment it must manage the variety that it faces.

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All dynamic systems can be seen as adapting to perturbations to survive and to fulfil their goals.

Knowledge is a mechanism that makes systems more efficient in surviving different circumstances, by short cutting the purely blind variation and selection they have to do.

A selector is a system capable of selecting variation. (Thus a selector can be understood as as agent of will. ) Knowledge functions as an anticipatory or vicarious selector. A vicarious selector carries selection out in anticipation of something else, e.g. the environment or "Nature" at large...

One can also imagine anticipatory selectors making different selections under different circumstances, compensating different perturbations by different actions. This kind of anticipatory selection has the advantage that inadequate internal variations will no longer lead to the destruction of the system, since they will be eliminated before the system as a whole becomes unstable. Thus anticipatory selectors select possible actions of the system in function of the system's goal (ultimately survival) and the situation of the environment. By eliminating dangerous or inadequate actions before they are executed, the vicarious selector forgoes the selection by the environment, and thus increases the chances for survival of the system.

... [A] fundamental concept of Metasystem Transition Theory is that of immortality. We understand immortality as the limit of stability, infinite survival, duration, persistence, and lack of change or variety. It is often observed that the phrase "survival of the fittest" is a tautology. We understand it more as a definition of fitness in terms of survival, and hence of stability...

Fitness is an assumed property of a system that determines the probability that that system will be selected, i.e. that it will survive, reproduce or be produced.

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In summary, a system will be selected if: 1) its parts "fit together", i.e. form an intrinsically stable whole, 2) the whole "fits" its environment, i.e. it can resist external perturbations and profit from external resources to (re)produce.

[See also resilience.]

In order to maximize fitness in a predictable environment, it pays to invest resources in long-term development and long life (K selection); in a risky environment, it is better to produce as much offspring as quickly as possible (r selection).

The test of a system in the Ω-stage [of the Adaptive Cycle] is its capacity to survive in the face of extreme disturbance or disordered collapse. A system must maintain vital functions throughout the crises.