Subject: Re: NANFA-L-- two interesting articles
dlmcneely at lunet.edu
Date: Wed Oct 20 2004 - 10:32:29 CDT
I've embedded some stuff below, but don't claim to understand evolution as well as someone like Peter J. Gould did.
Dave
David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email: dlmcneely at lunet.edu
telephone: (405) 466-6025; fax: 405) 466-3307
home page http://www.lunet.edu/mcneely
"Where are we going?" "I don't know, are we there yet?"
----- Original Message -----
From: Irate Mormon <archimedes at bayspringstel.net>
Date: Tuesday, October 19, 2004 11:49 pm
Subject: Re: NANFA-L-- two interesting articles
> It is clear to me that our current
> understanding of how evolution works is deeply flawed. Natural
> selection -
> well, that's a little more clear cut. But it seems to me that
> random mutation
> is not the mechanism of evolution.
Most biologists do consider random mutation to be important as a source of new genetic variability, although they also consider that most genes have existed for so long that new mutations are extremely rare. In other words, most possible sequences for most genes have cropped up and continue to do so. But occasionally, a mutation occurs in an environmental context that changes its value relative to other alleles. And, not all alleles have differential value, and so they persist simply because there is no selection. But they are important for looking at phylogeny.
>There appears to be some
> reservoir of
> genetic material which organisms can draw from, which is not
> commonly considered
> to be important. For example, how much of the "junk" DNA, that
> doesn't seem to
> code for anything, actually holds real information?
New data reveal that a lot of so called "junk" DNA actually has a function, though not in the classical Mendelian genetic sense. More can be found in a couple of recent Sci. Am. articles which I will have to look up before I can quote the bibliographic data.
> And what is
> the purpose of
> mitochondrial DNA?
This one is pretty straightforward. It codes for the enzymes that function in the mitochondria. Quoting from the biology text by Campbell, Reece, and Mitchell: "The products of most mitochondrial genes make up the protein complexes of the electron transport chain and ATP synthase ... "
>
> These questions will no doubt seem ignorant to some of you,
So? For me, questions are a part of my method of curing my own and my students' ignorance. Ignorance is just a state that provides an opportunity.
> Supposedly, you have to have a
> certain amount of
> genetic diversity in order for a population to survive over the
> long haul - and
> yet, all life is supposed to have originated from a single
> replicator molecule
> which resembles DNA in some fashion. I don't understand how both
> of these
> theories can be true.
During prebiotic evolution, molecules were competing against other molecules. The evolutionary mechanisms were not identical to those in play now, because the chemicals were not organisms. Random mutation was probably very significant to those molecules, and it generated the beginnings of the genetic diversity that became important in surviving lineages. And BTW, the original informational molecule was probably an RNA.
>
> > I just want to
> see some
> logical consistency - something that a mathematician or a
> physicist can grasp.
One excellent evolution text is the one by Ridley, from Blackwell Scientific.
Or you might be interested in the very recent treatise on evolution by the late Stephen J. Gould. You can find either book on Amazon.com.
Ridley and other evolutionists present mathematical models that describe their theory and are a part of it. Allele frequency and change in populations is the classic of course, and that is modeled by the Hardy-Weinberg theorem. I'm only a so-so mathematician, but with great effort I can wade through some of the stuff in evolutionary theory. Check it out, you might do a lot better than I do. It is fun stuff.
Dave Mc
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: Fri Dec 31 2004 - 11:27:50 CST