[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: up!up!and away!



Gustav Derkits wrote:

> 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".

I'm no expert on philately, but I understand that it does not
typically involve the derivation and testing of quantitative
mathematical models.  I think you are misrepresenting Alvarez.

> A one-dimensional random walk model does not work.

It correctly predicts the numbers of species of different complexity,
does it not?  And it does so with a minimum of assumptions.
 
> 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)...

Obviously evolution isn't a random walk at all, because of selection.
But Gould's model incorporates the null hypothesis that there is no
consistent selection for greater or lesser complexity.  As the
observed facts fit the model, there is no evidence to reject the null
hypothesis.

[some evolutionary genetics snipped]

> 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.

What do you mean why you say entropy is a "force" driving the
enlargement of the genome?  Do you mean that genomes expand and shrink
at random, just as Gould claims phenotypic complexity does?  Or do you
mean that entropy forces genomes to expand (in which case, why have
the majority not expanded)?

Bill Adlam
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com