PN:
But your example is post-hoc, "radiation after the introduction of a novelty,"
and assumes the point at issue, namely, macroevolution. I'm talking about
flies in population cages. Real-time morphogenesis, if you will, where we
perturb a developmental system and watch what happens.
Here's how McKinney and McNamara (1991:339-40) describe the problem:
It seems very likely that the novelty producible from a
chicken is considerably less "novel" than that producible
from a poorly integrated, simple metazoan ontogeny of the
later Precambrian....The general result of the growth of
developmental intertia has been to make the biosphere,
as a whole, less amenable to change.
"Developmental inertia" here means that complex metazoans aren't
fond of having their developmental regulators tinkered with. If they make
it through development at all after a homeotic mutation, they're good
candidates for bottles filled with preservatives -- not for reproductive
success.
So why not take the reality of "developmental intertia," and read that
information back into the history of life? Because that makes common
descent look pretty iffy. And everybody knows common descent is true.
Right?
(Puzzle. Describe a "poorly integrated, simple metazoan ontogeny
of the later Precambrian" in a testable format.)
TG:
>No response to my comment on cleavage patterns?
What should I say? What's a law of form or a principle of self-organization?
Here's how I see it:
1. Offspring have the cleavage patterns their parents had.
2. Those cleavage patterns are not amenable to change (i.e.,
stably heritable change) by mutation.
I just wondered if I'd miss a corner of the literature where someone had
experimentally demonstrated (2). If so, I'd like to know.
Lastly, Terry wrote:
TG:
>there are a few professionals, a mere handful, and as I get to know
>more and more of them personally, I find that they are driven primarily by
>a commitment to a certain view of origins that FORBIDS their acceptance of
>the scientific status quo, however well substantiated and well accepted it
>is.
I'm sure I have all kinds of disreputable motivations ("a certain view of
origins"). Let's put those to one side. When I read Gilbert et al., I
want to know how they've solved the problems well-known to neo-Darwinians,
and well-known to Darwin, too, as far as that goes. Gilbert et al. wrote a
beautiful, suggestive, thoughtful paper. But the stubborn questions are
unanswered. So I'm being a pest and reminding you (Terry), Denis, and the
others on this list not to forget those questions. That's all.
Back to lurking. A friend on this list reminded me that I have other work
to do, and he's right.
Paul Nelson
P.S. Denis, I'd like very much to hear your thoughts on all this -- via
e-mail, maybe? Please copy me on whatever you post to this list.