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RE: up!up!and away!
Steven J. Gould presented this argument in "Drunkard's Walk"
and also at his talk at Dinofest. This is the kind of thinking
that led Luis Alvarez to call paleontologists "stamp collectors".
A one-dimensional random walk model does not work.
The random walk that constitutes evolution is a kind of diffusion
in two related spaces: sequence space (Manfred Eigen) and
phenotype space (Dawkins, Maynard-Smith). Sequence
space is the space of genetic (discrete math) information.
Phenotype space, which Maynard-Smith called "protein space"
(actually his paper is unclear about what he meant) and was
explored in its digitized approximation by Dawkins in the "blind
watchmaker" work is the space of morphological forms of
organisms. Until recently, paleontology was done in a
subspace of phenotype space (the bones alone).
The genetic code for each organism can be represented by a point in
a sequence space. Evolution involves not only changes in
position of that point (mutations), but also enlargement of
the base space itself when DNA duplicates (not replicates)
genes. This is one of the principal enabling mechanisms behind
the evolution of complexity. Mutations only rearrange the points in a
fixed space. Polyploidy makes the space bigger for
mutations to work in.
Small bacteria have about 10-100 kB of genetic information.
Humans have about 600 MB and we do not have the
largest number of genes(I think a mudfish does). There
has been a gradual increase in the number of genes
in the most complex living beings and in the information
stored in those genes as time has gone by. The "force"
driving the enlargement of the genome is entropy
and polyploidy makes it possible to access the sequence
space into which life expands.
Evolution is the (really complex) feedback filter which operates on
populations of organisms directly through phenotype space,
with considerable amounts of random noise.
> From: Bruce Danz[SMTP:email@example.com]
> Reply To: firstname.lastname@example.org
> Sent: Sunday, March 21, 1999 10:23 PM
> To: email@example.com
> Subject: up!up!and away!
> On Sunday, 21 March, John Bois wrote:
> And yet over evolutionary time there has been a very definite increase
> complexity. Once upon a time there were only single celled things. Now
> we have colonial and even integrated systems. I suppose this complexity
> opens up new niches and thus is adaptive. But, in absolute terms, there
> is no superiority inherent in this idea--indeed, the simple may inherit
> the Earth.
> I recall a televised interview with Steven J. Gould a few years ago in
> which he was asked to explain the apparent increase in complexity of
> organisms over time. I thought his explanation made sense and I will
> try to provide my recollection of it, probably spiced with my own
> Think of evolution as a street and one side of that street is bordered
> by a continuous wall. The simplest forms of life may be pictured as
> growing next to that wall, and more complex forms of life growing
> further out from the wall. The more complex the form of life, the
> further from the wall it grows. Since living things can't get any
> simpler than the simplest living things already next to the wall, the
> development of new organisms will appear to be towards more complexity,
> away from the wall, because that is where there is more space. This
> doesn't preclude things becoming simpler but there is more "room"
> towards complexity.
> This analogy works for me, anyway.
> Bruce R. Danz