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From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.origins
Subject: Re: Now more than ever.  PART I
Message-ID: <477@psivax.UUCP>
Date: Fri, 31-May-85 16:01:59 EDT
Article-I.D.: psivax.477
Posted: Fri May 31 16:01:59 1985
Date-Received: Sun, 2-Jun-85 20:39:22 EDT
References: <297@cmu-cs-edu1.ARPA> <mhuxt.879> <1556@dciem.UUCP> <884@mhuxt.UUCP> <1200@cbosgd.UUCP>
Reply-To: friesen@psivax.UUCP (Stanley Friesen)
Distribution: net
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 65
Keywords: entropy, evolution

In article <1200@cbosgd.UUCP> rlp@cbosgd.UUCP (Bob Platt) writes:
>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.
>---
	But this still does not address the other aspect of Jeff
Sontag's objection, that is justifying treating a species as a
thermodynamic system. Even the quotes only specify *how* one would
treat a species as a thermodynamic system, not the reasons why doing
so might be permissible. In short Dr Thom is here making a conceptual
leap without adequate reasons(at least as far as the quoted excerpts
are concerned). The problem with the treatment is that living things
are *not* particles on the same sense as atoms in a gas(a typical
thermodynamic system). One theoretically important difference is that
particles of the same type in the physisist's sense are *indistinguishible*
while conspecific organisms are fully distinguishable(that is they are not
interchangeable without changing the state of the system).

>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.
>
	And in my opinion also for inadequate justification of a major
conceptual leap.
-- 

				Sarima (Stanley Friesen)

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