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<12.1 Is molecular evolution contrary to the second law of
< thermodynamics?
<12.1.1 Thermodynamics and the creation of "order" by evolution
<Thermodynamics and the theory of evolution by natural selection
<are among the great scientific theories of the nineteenth century.
<Yet almost immediately after the introduction of these two great
<theories they were pitted against each other. The opinion that
<evolution was contrary to the second law of thermodynamics was
<pushed by scientists who did not accept evolution. In the twentieth
<century this alleged conflict has been a favorite theme of the
<Biblical creationists and of the creation-science advocates
<(Wilder-Smith, 1981; Gish, 1989).
< An isolated system is one which _does not_ exchange heat or work
<with another system. The second law of thermodynamics states that
<the Maxwell-Boltzmann-Gibbs entropy of an isolated system does not
<decrease; it is, in general, not a conservation law since entropy
<is conserved only in reversible processes. Entropy is regarded as
<a measure of 'order', sometimes without bothering to define 'order'.
<Thermodynamics, as it was viewed in the nineteenth century,
<predicted a 'heat death' of the universe in which all bodies in
<the universe will be at the same temperature in a state of complete
<'randomness' or 'disorder'. (Think of it as the death of heat
<exchange, not a death by heat.) Evolution, on the other hand, so
<it was thought, predicted an increase in 'order' in the sense that
<more highly evolved organisms were considered to be more 'orderly'.
<Thus the reason for the conflict between the evolutionists and
<the creationists is that the second law was perceived to predict
<increasing 'disorder' while the theory of evolution was perceived
<to predict increasing 'order'. The notion that a paradox exists
<between biological evolution and the second law of thermodynamics
<persists today and is perceived to require resolution (Waldrop,
<1990).
< As I shall show, a proper understanding of both evolution and
<the second law of thermodynamics demonstrates that they are not
<in conflict and that the supposed paradox is merely a play on
<words.
<[...]
< Scientists who defend evolution have been caught, much as
<Br'er Rabbit by the Tar Baby, in a word-trap implying that
<evolution leads to organisms that are increasingly more 'orderly'.
<As I have mentioned in this book several times, it is perilous
<for the scientist to use words in their everyday meaning to express
<scientific concepts. One should remember that in science these
<words are merely names for mathematical functions and have no
<other meaning in themselves.
<[...]
< Kitcher(1982) believes that there is a dilemma and that the way
<out is to declare that life is an open system receiving work and
<heat and that in such systems entropy _decreases_ over time. This
<is true but inapplicable. Although organisms use energy, as I have
<pointed out (Yockey, 1974, 1977c), the entropy that is pertinent
<in the genetic system is the Shannon entropy or the Kolmogorov-
<Chaitin algorithmic entropy. Kitcher(1982), along with many others,
<is unaware that each probability space has its own peculiar entropy.
<Two probability spaces that are not isomorphic have no relation
<except in those cases where such a relation is established by a
<code. Patterson (1983) also makes the mistake of confusing order
<with complexity; he cites some references in which the Biblical
<creationists claim that evolution is impossible based on the false
<notion that evolution violates the second law. He believes that
<highly organized molecular assemblies have a low entropy. He
<thereby falls into the word-trap set by the creationists of using
<words like 'order' and 'complexity' without defining them
<mathematically. His explanation in other words is rather lame.
< [...] Even a scientist as eminent as Eddington (1931a) believed
<there is a conflict between the second law of thermodynamics and
<evolution:'We must of course drop the theory of evolution, or at
<least set alongside it a theory of anti-evolution as equally
<significant'. As usual, Eddington could put his finger on the
<problem even if a solution was not available at the time. Later in
<that article he pointed out that it is _organization_ that increases
<in evolution. But he had no mathematical definition of organization.
<This had to await the definition given by algorithmic entropy as
<discussed in section 2.4.1.
< As has already been discussed in this book (section 2.2.2),
<the entropy to which the second law of thermodynamics applies
<is the Maxwell-Boltzmann-Gibbs entropy. This entropy addresses
<the energy efficiency of heat engines, the directions of chemical
<reactions and, in biology, the energy economy of the cell. Thus
<it is the 'orderliness' of energy that is addressed by the second
<law of thermodynamics. Organisms cannot defy the second law: there
<has never been any question in sober minds that organisms are not
<perpetual motion machines (although small children may seem to be).
<One should remember that classical thermodynamics deals only with
<energy and the Maxwell-Boltzmann-Gibbs entropy. It is even
<independent of the existence of atoms.
< All probability spaces have an entropy peculiar to them (section
<2.2.1). The entropy that is applicable to the case of the evolution
<of the genetic message is, as I believe the reader should now be
<convinced, the Shannon entropy of information theory or the
<Kolmogorov-Chaitin algorithmic entropy. In thermodynamics one has
<two invariants of the system, namely the mass of the system and
<the conservation of energy as expressed in the first law of
<thermodynamics. In communication systems one has only the
<conservation of the number of letters. There is no invariant
<corresponding to energy in the case of communication systems and
<consequently no analogue of temperature. Furthermore, the Shannon
<entropy and the Maxwell-Boltzmann-Gibbs entropy are based on
<probability spaces that are not isomorphic to each other.
<Consequently, for this reason also, as I have pointed out before
<(Yockey, 1977c), they have nothing to do with each other.
<Therefore it is easy to see that thermodynamics has nothing to
<do with Darwin's theory of evolution.
<12.1.2 The increase in genetic algorithmic entropy during evolution
<The Kolmogorov-Chaitin genetic algorithmic entropy is increased
<in evolution due to the duplications that occurred in DNA. [...]
<Thus the genetic algorithmic entropy increases with time just
<as the Maxwell-Boltzmann-Gibbs entropy does. Therefore creationists,
<who are fond of citing evolution as being in violation of the
<second law of thermodynamics (Wilder-Smith, 1981; Gish, 1989),
<are hoist by their own petard: evolution is not based on increasing
<_order_, it is based on increasing _complexity_. In fact, evolution
<requires an increase in the Kolmogorov-Chaitin algorithmic entropy
<of the genome in order to generate the complexity necessary for the
<higher organisms. Let us recall from section 2.4.3 that _highly
<organized_ sequences, by the same token, have a large Shannon
<entropy and are embedded in the portion of the Shannon entropy
<scale also occupied by _random sequences_.Evolution is not in
<violation of the second law of thermodynamics. This is what any
<reasonable scientist believes; nevertheless, it is important to
<avoid word-traps and to reach the correct conclusion for the correct
<reasons.
<-- Hubert Yockey,_Information Theory and Molecular Biology_,
< Cambridge University Press, 1992, p. 310-313.
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Brian Harper
Associate Professor
Applied Mechanics
Ohio State University
"Aw, Wilbur" -- Mr. Ed