[...
> There are several ways of defining biological complexity.
>
> Common metrics involve things like counting the number of different
> cell types an organism produces - and estimating the "kolmogorov
> complexity" of its genome.
>
>
> Though the definitions may differ in detail, they tend to be
> correlated - and in discussions like this it tends not to matter
> very much which one you use.
> -- 
> __________
>  |im |yler  http://timtyler.org/  tim{at}tt1lock.org  Remove lock to reply.
>

Which is exactly why threads such as this quickly erode into philosophical
debates.

So for example (and in loose reference to one of your other posts), there
are many, many groups of bacteria that cooperate, differentiate into a
multitude of morphologically distinct cell types, and build elaborate,
macroscopic (differentiated though monoclonal) structures.  [See, for
examples, hyphae-producing Streptomyces, akinete and/or heterocyst forming
cyanobacteria, iron-scavenging Shewanella macrocolonies, or the wondrous
assortment of organisms that comprise e.g. thermophilic, alkaline microbial
mats].  Yet the Kolmogorov complexity of the genomes from these organisms
are indistinguishable, they all have roughly the same number of genes, the
degree of their metabolic and protein interaction networks are all scale
free (power-law distributed) with nearly identical scaling exponents, etc.
etc. ad nauseum.  Find me some underlying, unifying Standard Model of
Complexity that has evaded notice in all studies to date, and I'll pay all
the publication charges on your paper.

To put it simply, there is no metric that has ever been proposed, whether it
be here, in the work of Gould, Dawkins, Shannon, Kauffman, etc., or in the
scientific literature, that is able to correlate some /generalizeable
complexity gradient/ with the genomes, genotype, or known evolutionary
trajectory of any prokaryotes.  Given any one of the measures that we might
collectively come up with to define complexity, one ends up with entirely
different arrangements of 'simple->complex' organisms.

> Though the definitions may differ in detail, they tend to be
> correlated - and in discussions like this it tends not to matter
> very much which one you use.

To put it another way, it *only* matters which one you use.

One of the only promising new infusions into this somewhat dismaying debate,
IMO, comes from Wolfram's Principle of Computational Equivalence -- we have
so much trouble categorizing complexity because there are only two
categories to be found; things are either complex or they are simple.  (Not
that I believe this just yet, but it's a much needed new angle).
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