Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 alpha 4/15/85; site cbosgd.UUCP Path: utzoo!linus!decvax!bellcore!allegra!ulysses!mhuxr!ihnp4!cbosgd!rlp From: rlp@cbosgd.UUCP (Bob Platt) Newsgroups: net.origins Subject: Re: Now more than ever. PART I Message-ID: <1200@cbosgd.UUCP> Date: Thu, 23-May-85 18:23:13 EDT Article-I.D.: cbosgd.1200 Posted: Thu May 23 18:23:13 1985 Date-Received: Sun, 26-May-85 21:41:56 EDT References: <297@cmu-cs-edu1.ARPA> <1556@dciem.UUCP> <884@mhuxt.UUCP> Reply-To: rlp@cbosgd.UUCP (Bob Platt) Distribution: net Organization: AT&T Bell Laboratories, Columbus Lines: 76 Keywords: entropy, evolution Summary:applying thermodynamics to evolution > from Jeff Sonntag: > > ...the second law can be > applied to evolution only insofar as evolution can be described in terms of > heat concentration and temperature distributions *or* if entropy can be > defined somehow in terms which are more descriptive of biological systems. This has been attempted, although exactly how succesfully I can't say, as the mathematics are very complicated and beyond me. My source is "Structural Stability and Morphogenesis" by Rene Thom (Benjamin/Cummings 1975). I won't reproduce the specific mathematical details here, but the following quotes give the flavor of Thom's approach: "If two systems S1 and S2, with total energy c, are thermodynamically coupled, the equilibrium regime will occur at the value of t for which the total entropy S1(c-t) + S2(t) is maximum. If there is only one sufficiently sharp maximum, the joint system will evolve toward this state and stay there, neglecting fluctuations. "The importance of thermodynamical coupling comes from the fact that, if two dynamical systems over two contiguous open sets U1 and U2 are put into spatial contact, we can suppose (without any special hypothesis concerning the nature of the interaction) that the two systems are thermodynamically coupled." --- In the context of evolution, the "two systems" may be interacting species, such as wasps and orchids: "We must not forget that the essential object of study in biology is not the isolated individual but the continuous form in space-time joining parents to descendants; more precisely, when two or more species having some functional interaction between each other, such as predation or being an auxiliary in the fertilization process, it is necessary to consider the total figure in space-time, the union of all forms associated with each species. Then, for each adaptive process, we can probably find a function S of the local biological state expressing in some way the complexity of the state with respect to the process considered, and the configuration will evolve between two times t0 and t1 (e.g. parent at age A and offspring at same age) in such a way as to minimize the global complexity of dt "In this way the minimum complexity and hence the most economical adaptation of the process will be realized. Natural selection is one factor in this evolution, but I myself think that internal mechanisms of Lamarckian character also act in the same direction." --- He of course realizes that this maximization of entropy occurs against a backdrop of negative entropy introduced by the sun: "The solar photons arriving in contact with the soil and seas are immediately stopped, and their energy abruptly degraded into heat; in this way the discontinuity of the earth and water surface is also a shock wave, a cliff down which the negentropy of the sun's rays falls. Now, life can be considered as a kind of underground erosion of this cliff, smoothing out the discontinuity; a plant for example is nothing but an upheaval of the earth toward the light, and the ramified structure of its stem and root is the same as that found when a stream of water erodes a cliff..." --- Thom's ideas are highly speculative, and has been criticized (rightly or wrongly) for couching his speculations in highly abstract terms understandable only to highly trained mathematicians. Nevertheless, he has presented a theory that specifies biological measures of entropy and information, makes predictions, and is falsifiable. Joe Knapp ATT-BL Columbus OH -- +----+ R. L. Platt /| /| AT&T Bell Laboratories +-|--+ | Columbus, Ohio | +--|-+ |/ |/ cbosgd!nscs!rlp +----+ (614) 860-4850 "Wherever you go, there you are"