Subject: Re: NANFA-L-- two interesting articles
From: Peter Unmack (peter.lists at)
Date: Wed Oct 20 2004 - 01:02:22 CDT
On Wed, 20 Oct 2004, Irate Mormon wrote:
> It really drove home the point that biology is not a hard science, with
> predictable and repeatable results....This is why I am critical (to
> some, perhaps overly so) of the many studies which pop up from time to
> time, especially in regard to genetics.
I think this depends somewhat on exactly what topic one is debating, but
yes, generally speaking biology is more difficult to nail down, but it is
also a younger science in many respects, and we only just getting to a
better understanding on one of the core parts of biology, DNA. Although,
as pointed out, DNA isn't everything either. Some genetics should be
viewed very carefully, but I think you are mostly referring to aspects
that relate more to conservation biology and related issues, many aspects
of which are not clear cut.
> 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
Natural selection works on survival of the fittest. Variation exists in
populations, and if certain variations are favorable relative to survival
then natural selection is likely to favor those variations. If this
variation is heritable then it increases in frequency in future
generations. Mutation is the source of this variation. If you don't
think mutation is real, or is unimportant (I'm not sure exactly what you
are suggesting really), then where does this variation come from? It is
pretty clear in the lab that by causing mutations you can create new
genotypes (folks who study things like fruit flys and zebra danios do this
every day). Thus one can demonstrate a pretty clear relationship in my
mind between mutations creating new genotypes which would be subjected to
> 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? And what is the purpose of
> mitochondrial DNA?
Mitochondrial DNA is largely related to cellular respiration (generating
energy for the cell) and is generally accepted to have come about via an
early symbiotic relationship (before the evolution of plants or animals).
And yes, at least some junk DNA is not junk DNA and we are finding out
more and more all the time. However, some junk DNA is almost definately
junk DNA. But, when it comes to _any_ DNA there is only one way that
variation is originally generated and that is via mutation. Mutation is
not completely random per se, and the types of mutations that we see are
not totally random either, eg some changes are more likely to occur than
others (eg, a T is more likely to change to a C than an A or G), also,
more than one codon can code for the same amino acid, and there can be
codon useage bias (eg, when you look at an amino acid that could be coded
for via two or more DNA sequences (eg, glutamine can be CAA or CAG), but
if you look at the frequency of the two codons coding for that amino acid
in a protein they will not necessarily be 50% each.
> 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.
Your first statement is totally theoretical and not well understood yet,
but I suspect that genomics will begin to provide answers at some point in
the near to moderately near future (10-20 years). I think the other thing
that many people can't appreciate is time. It supposedly took about 2-2.5
or so billion years to go from one celled organisms to multicellular ones.
Yes, I said 2-2.5 billion, that is an amazing amount of time! Early
vertebrates existed around 550 million years ago, again, an incredible
amount of time. Even closely related species usually are seperated by at
least hundreds of thousands to a few million years, which again is still a
massive amount of time. Now, I certainly have a hard time comprehending
what a million years must be like, let alone longer times. It's just not
a simple thing to think about. But think about it.
> I'm not trying to resurrect the old creation vs. evolution debate here,
> and I don't wish to see that bandied about on the list. I just want to
> see some logical consistency - something that a mathematician or a
> physicist can grasp.
Unfortunately, not everything in the world can be reduced to an equation
as easily as math and physics, and even then things are not rock solid
(eg, physics still has many major unsolved problems even relative to very
simple things). I'm not sure if this sheds any light or not....
I also don't claim that everything I have said in here is exactly accurate
either as most of it is off the top of my head and it is rather late...
But, I will mention one interesting website that deals with some of these
issues. http://www.talkorigins.org/ I'd suggest if you are interested in
this topic that you investigate that site.
Canadian River, Oklahoma
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: Fri Dec 31 2004 - 11:27:50 CST