From: mrl@st-andrews.ac.uk (  Michael Ladomery)
Newsgroups: talk.origins
Subject: Re: Topic for Discussion?
Date: 25 Jan 93 19:20:40 GMT
Organization: St. Andrews University, Scotland.

In article <1jo29o$srt@agate.berkeley.edu> philjohn@garnet.berkeley.edu (Phillip Johnson) writes:
>

>biology, Chris Colby begins with the question: "What is
>Evolution?"  He answers by citing as an example the familiar case
>of the peppered moth:
>
>"The kind of evolution documented above [in the peppered moth
>example] is called "microevolution".  Larger changes (taking more
>time) are termed "macroevolution".  Some biologists feel the
>mechanisms of macroevolution are different from those of
~~~~~~~~~~
>microevolutionary change. Others, including  myself, feel the
>distinction between the two is arbitrary.  Macroevolution is
>cumulative microevolution."
>
>This wording acknowledges that "some biologists" do not think
>that the peppered moth example illustrates a creative process
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>that can produce new species, much less new complex organs. 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	
The above quote is a consideration
about mechanisms; ie some biologists may believe that the mechanisms
of macroevolutionary changes (genetic etc) are distinct, such as
radical genetic rearrangements giving rise to radical changes. 
I fail to see how the underlined interpretation follows.

>Indeed, that is true.  To give only a single example, the
>doctrine that "macroevolution is cumulative microevolution" is
>the theory that Stephen Jay Gould once pronounced to be

Pardon me: doctrine or theory?

>"effectively dead," in a paper in which he endorsed a modified
>version of the macromutational views of Richard Goldschmidt. 
>(See Darwin on Trial, Chapters Two and Three, esp. p. 40).  Of
>course an adaptive macromutational mechanism -- in Gould's words
>"a potential saltational origin for the essential features of key
>adaptations" -- has yet to be demonstrated.
>
>I would say that it is reasonable for a well-informed observer to
>conclude that macroevolution (i.e. the creative process that
>produced complex plants and animals in the first place) is not 
>"cumulative microevolution" (i.e. the peppered moth example writ
>large over geological time).  

I fail to understand how you reach this conclusion.
I would also ask you this, and I suggest it's an important question:

Given that you acknowledge that microevolutionary changes occur
(if you endorse that terminology) such as the peppered moth's
changes over a short time frame, what do you propose is the reason 
why cumulative microevolutionary changes over much longer periods
coupled with reproductive isolation events DO NOT lead to speciation?
I would be very interested to know, especially in a genetic context.

>If so, it is also reasonable to
>conclude that the mechanism of macroevolution is an unsolved
>mystery.  This does not necessarily imply supernatural creation,
>because it is possible that science will discover a naturalistic
>mechanism at some time in the future.  It is also not "anti-
>science."  Indeed, students with inquiring minds may be more
>attracted to the field of evolutionary biology if they are told
>that they have an opportunity to try to solve a big mystery,
>rather than merely to fill in the details of the neo-Darwinian
>picture.  Of course, there can be no guarantee that they will
>succeed.  

Were we to have a complete understanding of molecular biology, of
the genes' products and interactions, were we to know how
development proceeds in detail, were we to know of all the ways
in which genetic changes can relate to phenotypic changes, then
we'd be much better able to hypothesize mechanisms of "macroevolution".
I would however distinguish between the theory of the common
descent of species, which is widely if not almost universally
accepted among biologists, and the detailed mechanisms whereby
such evolution occured, the latter being, sure enough, a big
mystery.

cheers