Cybernetics • Regulation In Biological Systems • Selection 5

Regulation In Biological Systems


Ashby Cybernetics Figure 10.5.2

10/5.[concl.]   To make the assumptions clear, here are some simple cases, as illustration.  (Inanimate regulatory systems are given first for simplicity.)

(1) The thermostatically-controlled water-bath.  E is its temperature, and what is desired (\eta) is the temperature range between, say 36° and 37°C.  D is the set of all the disturbances that may drive the temperature outside that range — addition of cold water, cold draughts blowing, immersion of cold objects, etc.  F is the whole regulatory machinery.  F, by its action, tends to lessen the effect of D on E.

(2) The automatic pilot.  E is a vector with three components — yaw, pitch, and roll — and \eta is the set of positions in which these three are all within certain limits.  D is the set of disturbances that may affect these variables, such as gusts of wind, movements of the passengers in the plane, and irregularities in the thrusts of the engines.  F is the whole machinery — pilot, ailerons, rudder, etc. — whose action determines how D shall affect E.

(3) The bicycle rider.  E is chiefly his angle with the vertical.  \eta is the set of small permissible deviations.  D is the set of those disturbances that threaten to make the deviation become large.  F is the whole machinery — mechanical, anatomical, neuronic — that determines what the effect of D is on E.

Many other examples will occur later.  Meanwhile we can summarise by saying that natural selection favours those gene-patterns that get, in whatever way, a regulator F between the disturbances D and the essential variables E.  Other things being equal, the better F is as a regulator, the larger the organism’s chance of survival.


  • Ashby, W.R. (1956), An Introduction to Cybernetics, Chapman and Hall, London, UK.  Republished by Methuen and Company, London, UK, 1964.  Online.

cc: CyberneticsOntolog ForumStructural ModelingSystems Science

This entry was posted in Adaptive Systems, Ashby, C.S. Peirce, Communication, Control, Cybernetics, Evolution, Information, Inquiry Driven Systems, Learning, Logic, Mathematics, Peirce, Purpose, Regulation, Survival, Truth Theory, W. Ross Ashby and tagged , , , , , , , , , , , , , , , , , . Bookmark the permalink.

2 Responses to Cybernetics • Regulation In Biological Systems • Selection 5

  1. Pingback: Survey of Cybernetics • 1 | Inquiry Into Inquiry

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