Xref: utzoo sci.skeptic:7866 talk.religion.misc:34308 sci.bio:4244 sci.med:22128 talk.origins:13300
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!decwrl!mcnc!uvaarpa!haven!ncifcrf!fcs260c2!toms
From: toms@fcs260c2.ncifcrf.gov (Tom Schneider)
Newsgroups: sci.skeptic,talk.religion.misc,sci.bio,sci.med,talk.origins
Subject: Re: Evolution is NOT random
Keywords: mutation selection
Message-ID: <1996@fcs280s.ncifcrf.gov>
Date: 4 Jan 91 20:34:31 GMT
References: <1991Jan03.201603.25448@pmafire.inel.gov> <1991Jan4.160016.16574@ncsuvx.ncsu.edu>
Sender: news@ncifcrf.gov
Followup-To: sci.skeptic
Organization: NCI Supercomputer Facility, Frederick, MD
Lines: 96

In article <1991Jan4.160016.16574@ncsuvx.ncsu.edu> hes@ccvr1.ncsu.edu
(Henry E. Schaffer) writes: (ie, >)
>In article <1991Jan03.201603.25448@pmafire.inel.gov> reiser@pmafire.inel.gov
(Steve Reiser) writes: (ie, >>)

>The BIG question is whether the selective situation uncovered a
>pre-existing "good" mutation ("good" because it lets the bearer
>survive in this particular situation) or whether the mutation occurred
>afterwards to "help" the individual adapt to the selective situation.
>
>  This was an important question in biology, and it wasn't settled
>until the 1940's.  The "fluctuation test" of Luria and Delbruck
>(S.E. Luria and M. Delbruck, Genetics 28, 491, 1943) is considered
>to have settled the question, but probably took until around 1950
>before it was widely understood and accepted.  (Some of the delay
>was probably due to world events of that time.)  They showed that
>these adaptive mutations existed before the selective event and
>the selective event just exposed them to view (versus the alternative
>that the adaptive mutations occurred in response to the selective
>event.)
>
>  Therefore the mutations are random, but the "evolution" is in
>response to selective conditions and therefore is adaptive.

I think that the article refered to by the first poster may have been a spinoff
of the recent debate about mutation under growth inhibitory conditions.  Some
people claim that mutations appear to be directed to the particular genes where
a mutation would help the organism.  This APPEARS to run against the original
Luria Delbruck experiments!  I think that the original paper on the topic was:

@article{Cairns1988,
author = "J. Cairns
 and J. Overbaugh
 and S. Miller",
title = "The origin of mutants",
journal = "Nature",
volume = "335",
pages = "142-145",
year = "1988"}

So far as I know this has NOT been resolved!

>>and selective mutations occur allowing species to advance at an infinitely
>>faster rate than would be probable by random genetic mutation.

The original paper or the first poster has made a mistake:  "infinitely faster"
can't be right!

>  but this goes against what is known in biology - in fact, people
>have been trying hard to figure out ways to cause particular mutations
>to occur ("directed mutagenesis") and so far there has been little
>progress.

Nope, sorry Henry, but "directed mutagenesis" works just fine.  One can make
any changes one wants to a piece of DNA.  In some species one can put the
change back into the chromosome too.  There are many ways to do it and one can
confirm the results with well established sequencing techniques.

>>This finding suggests that evolution is harder to explain away than it
>>had been when statistical probabilities of evolution creating man was
>>used to suggest that it was necessary for a god to intervene.

This makes no sense to me.  There is no need to 'explain away' evolution.
Mutations are observed in the lab every day.  The sequence data indicates
common origins and variations.  The evidence for this is overwhelming if the
original poster would only go read a bit!

>  I don't think that evolution can be "explained away" even without
>this article.  All of the "statistical probabilities of evolution 
>creating man" arguments I have personally seen have been bogus.

Right.  And anyone who wants to argue should read this book first:

@book{Dawkins1986,
author = "R. Dawkins",
title = "The Blind Watchmaker",
publisher = "W. W. Norton \& Co.",
address = "New York",
year = "1986"}

>(They typically attempt to calculate the probability that in one
>cell division an amoeba mutates to a human cell, and calculate that
>in ways which systematically underestimate the probabilities of
>each of the factors involved.)  The creationists have a religious
>basis for wanting to deny evolution, and have a large variety of
>arguments "explaining away" evolution, but that's a different issue.

But, despite overwhelming evidence, not resolved!

>--henry schaffer  n c state univ

  Tom Schneider
  National Cancer Institute
  Laboratory of Mathematical Biology
  Frederick, Maryland  21702-1201
  toms@ncifcrf.gov