"Tim Tyler"  wrote in message
news:c7jqi2$19fl$1{at}darwin.ediacara.org...
> IMO, the thing that most urgently needs doing is:
> * Characterising the effect of introducing self-organising systems (and
>   evolving systems) on the plain-old thermodynamic entropy of systems.
>
>   This is already done in many respects - introducting a self-organising
>   system makes entropy increase faster, but - IMO - the point could do
>   with some further spelling out and banging home.

And, IMO, it does not make entropy increase faster.  But lets not revive
that old debate!

> There is also the task of characterising evolutionary progress in
> thermodynamic terms.  This is pretty much the task Kaufmann set himself.
> It's also basically the task your article addressed.

I disagree that the article addressed that task.  "Evolutionary entropy"
as defined in the article is definitely NOT thermodynamic entropy.
The article tries to characterize one aspect of evolutionary progress
using concepts that bear a _formal similarity_ to concepts from
thermodynamics.  Talking about "evolutionary entropy" is no more
a characterization in terms of thermodynamics than would talking
about gene flow be a characterization in terms of hydrodynamics.

[snip]
> As I pointed out, merely bombarding a living system with enough asteroids
> has the effect of reversing the trend towards complexity and technology
> accumulation.
>
> Thus, any analogy with the second law would be rather tenuous.

And the reason why the analogy is not as law-like as the second law
is that in this analogy, the "first law" is conservation of population
(i.e. number of organisms).  But the fact that the analogy does not
yield a universal law does not mean that the analogy is worthless.

At the heart of this paper is the simple observation that an "entropy"
can be defined for any conservative Markov process, coupled with
the observation that a population-structure transition diagram is
a definition of a Markov process.  There are a lot of other processes
in biology that can be structured as Markov processes, and an
entropy can be defined for each of them.  In fact, as I look back at
Brooks and Wiley, I can see that that is what they were doing, though
they were not very clear about it.  Whether any insight about evolution
can be gained by constructing and examining these analogies remains
to be seen, but it is frequently the case that looking at old facts in a
new way is enlightening.  So, I am happy that I ran across this paper,
even though it told me nothing about changes in population age
structure that I didn't already know.
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