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homeostasisHomöostase (ger.)

  • The maintenance of a dynamically stable state within a system by means of internal regulatory processes that tend to counteract any disturbance of the stability by external forces or influences; the state of stability so maintained; spec. in Physiol., the maintenance of relatively constant conditions in the body (e.g. as regards blood temperature) by physiological processes that act to counter any departure from the normal. (OED 2011)

    The steady states of the fluid matrix of the body are commonly preserved by physiological reactions, i.e., by more complicated processes than are involved in simple physico-chemical equilibria. Special designations, therefore, are appropriate:—‘homeostasis’ to designate stability of the organism; ‘homeostatic conditions’ to indicate details of the stability; and “homeostatic reations,” to signify means for maintaining stability.

    Cannon, W.B. (1926). Physiological regulation of normal states. Some tentative postulates concerning biological homeostasis. In: À Charles Richet, ses amis, ses collègues, ses élèves, 91-93: 91. (Reprint in: Langley, L.L. (ed.) (1973). Homeostasis. Origins of the Concept, 246-249: 246); cf. id. (1932). The Wisdom of the Body.


    The cöordinated physiological reactions which maintain most of the steady states in the body are so complex, and are so peculiar to the living organism, that it has been suggested (Cannon, 1926) that a specific designation for these states be employed—homeostasis.

    Cannon, W.B. (1929). Organization for physiological homeostasis. Physiol. Rev. 9, 399-431: 400. 


    Because genetic continuity is often broken and is replaced by environmental continuity, the community is fundamentally different from intraspecies populations or individual organisms, but it also partakes of certain aspects of organismic integration, division of labor, and structure, and maintains ecological homeostasis. The concept of the interspecies supraorganism has some real scientific basis and is useful both in relating many facts in ecology and in directing our investigations toward the relations of the parts of the coordinated whole (Lotka, 1944).

    Allee, W.C., Emerson, A.E., Park, O., Park, T. & Schmidt, K.P. (1949). Principles of Animal Ecology: 728; Odum, E.P. (1953/59). Fundamentals of Ecology: 25; id. (1969). The strategy of ecosystem development. Science 164, 262-270: 266; Trojan, P. (1984). Ecosystem Homeostasis.


    as soon as some improvement [in selective breeding] has occurred, the pressure of natural selection will tend to produce a regression toward the original state, that is to say, in the direction of recovery of the optimum genetic balance for fitness, which was then present. Hence, a certain amount of selection pressure is dissipated in order to overcome this tendency, and only the balance of it applies to further improvement. […] it seems clear that some such mechanism for a regressive tendency or a sort of genetic homeostasis is operative.

    Lerner, I.M. (1950). Population Genetics and Animal Improvemen: 143. 


    It has long been recognized that maximum hatchability in chickens and turkeys is obtained with eggs of intermediate size (Landauer, 1948). The simplest interpretation of this phenomenon is that an absolute physiological optimum size of egg exists for a given set of incubation conditions, higher embryonic mortality being found in eggs that are larger or smaller than this optimum. It now appears that this explanation somewhat oversimplifies the situation, and that the relationship between egg size and hatchability (or more properly reproductive fitness) involves an interaction between artificial and natural selection pressures or the phenomenon designated as genetic homeostasis. This term suggested by Lerner (1950) refers to the tendency of a population to maintain its genetic composition at an adaptive peak in the face of artificial selection pressures for one or more traits, and seems to be related to what Darlington and Mather (1949) have termed genetic inertia.

    Lerner, I.M. (1951). Natural selection and egg size in poultry. American Naturalist 85, 365-372: 365. 

    Genetic Homeostasis  
    Lerner, I.M. (1954). Genetic Homeostasis.

    homeostasis The maintenance of a relatively steady state or equilibrium in a biological system by intrinsic regulatory mechanisms; homeostatic.

    Lincoln, R.J., Boxshall, G.A. & Clark, P.F. (1982). A Dictionary of Ecology, Evolution and Systematics: 115.


    ecosystem homeostasis

    Trojan, P. (1984). Ecosystem Homeostasis.