Re: Comments on Snoke's approach

From: Pim van Meurs <pimvanmeurs@yahoo.com>
Date: Sat Sep 24 2005 - 12:33:53 EDT

Cornelius Hunter wrote:

> Randy:
>
>
>
> All this of course assumes that you've got different populations of
> self-replicating organisms and an environment to start with, but that
> too runs into this kind of problem. The bottom line is that the
> Darwinian notion that functional designs are produced by an unguided
> search process (that just happens to be in place) is not a good
> scientific theory.

Or that the argument is wrong? In this case you are presuming that full
DNA space needs to be searched. Secondly, Darwinian theory is not based
on an unguided search process (random search) but rather a guided
search. Once one realizes that the relevance of the concept of
evolvability and how evolution itself can evolve one comes to realize
why evolution has been so succesful. Recent data on protein space helps
understand how finding functional sequences may not be that hard but
let's for a moment focus on RNA.
Scientists like Peter Schuster, Peter Stadler, Walter Fontana and
others, have looked at RNA and found that it is characterized by a scale
free nature.

As is well known DNA sequences map to RNA or protein structures.

    *

      There are far more sequences than structures

    *

      Contains few highly-connected motifs and many less connected nodes

    *

      Motifs have a neutral network which extends throughout sequence space

For these frequent structures, their networks expand through sequence
space, this means that gor any given fold, one can traverse through
sequence space (that is change every nucleotide position) without
changing the structure of the fold. In addition these structures are
close in the sense that any such structure is within a small distance
from any random sequence.

In other word, given any motif it can be shown that via neutral
mutatations one can get within one or two non-neutral mutations of
another motif.

Cornelius' 'thought experiment' presumes that Darwinian theory has to
search the whole DNA space for it to find functional sequences. Science
has shown otherwise and thus once again, the Darwinian notion strongly
supports the data. Of course nothing Cornelius has presented here shows
that there are limitations to evolution.

In fact the following paragraph still remains mostly unsupported

Cornelius:

You also said that "One could argue effectively that once there exists a
reproducing organism, the probability that in time there would be a vast
diverse range of species is close to unity." Again, I don't know how one
could defend this. Everything we understand about population genetics
and adaptation points to limits to adaptation. And there is no effective
argument for how the intricate complexities in biology could have arisen
from a single cell. All we have are broad speculations based on the
presupposition that evolution has occurred.
 
As I have shown some very good hypotheses of the evolution of complexity
in biology exist. Just recently science provided a link between
vertebrates and invertebrate eye evolution. Slowly but steadily these
hypotheses are being strengthened by new data. Not only that, but there
is few data suggesting that there are limitations to adaptation as
envisioned by Cornelius.

Scale free networks btw can arise through the simple process of gene
duplication and preferential attachment. No miracles required. That we
find lots of evidence of such gene duplication is just icing on the cake
for evolutionary theory.
Received on Sat Sep 24 12:36:12 2005

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