TG
____________________
Guys:
I was going to send this, while in hot-head mode, to the evolution
reflector, only now I can't find the address. Which is good. My head
has since cooled and I don't need another protracted Internet debate
gobbling up my time.
But I will send this to the three of you, since you've each commented
on the paper -- and this is what I would say to you anyway over a pint
of beer (Sam Adams for me, thanks), one-on-one.
Best,
Paul.
P.S. Second thought: Terry, would you mind posting this, including
this note to the three of you, to the reflector? I promise not to ask
again!
To the evolution reflector:
In light of the recent commentary on Gilbert et al.
("Resynthesizing Evolutionary and Developmental Biology,"
_Developmental Biology_ 173 [February 1996]: 357-372, I'm leaving
lurker status temporarily, and will keep this short and sweet.
[About me: I'm a Ph.D. candidate at the University of Chicago,
where my dissertation addresses the relationship between
development and common descent. Terry Gray, Denis Lamoureux, and
some of the other old-timers know me from the ancestral form of
this reflector, when Phil Johnson ran it.]
Gilbert et al. is certainly a step forward for evolutionary
theory. For starters, it rolls like a tank over the tendentious
"evolution is change in gene frequency" definition regularly sold
to the naive on talk.origins by those who should know better.
But fellas, we've got a long way to go. I wonder if Terry or
Denis or other enthusiasts for Gilbert et al. 1996 can tell me:
1. If they know of any homeotic mutants -- in mice, Drosophila,
C. elegans, or wherever -- that don't need a full-coverage Blue
Cross plan, or, actually, funeral arrangements. More prosaically:
which known homeotic mutants are good candidates for adaptive
(viable and fertile) evolutionary change?
2. If they know of the demonstration of heritable changes to
cleavage patterns in any metazoan group?
3. If they've thought 100% seriously about the following passage
from Gilbert et al.:
The segmentation of Drosophila and the segmentation of
vertebrates had been a classic example of analogy.
Yet, here it was seen as being directed by a
homologous set of genes. This demonstration of
"homologous" genes for "analogous" processes and
structures has wreaked havoc with our definition of
analogy and homology. (p. 364)
For "wreaked havoc," see "stood on its ear," "turned upside down,"
or, more modestly, "left us scratching our heads about the nature
of evolutionary change." In brief, macroevolutionary change
appears not to flow from mutations in nucleic acid outwards to the
phenotype (via development), because the regulatory genes seem
boringly similar across phyla.
A couple of weeks ago, I saw the galleys for Rudy Raff's new book,
_The Shape of Life_ (Univ. of Chicago Press, 1996; 520 pp.), due
out in a couple of months. Raff develops the ideas in Gilbert et
al. 1996 at great length, and with style and acumen. This is
evolutionary theory as it ought to be done.
But don't kid yourselves, guys. Gilbert et al. 1996 belongs on
Phil Johnson's score card. They confirm what he's been saying,
and provide NO evidence (see questions 1 and 2 above) that the
"hang on a sec, we've almost got a theory of macroevolution"
school is on the right track.
Sorry for losing my temper, but every now and then we lurkers have
to break radio silence.
Paul Nelson