At 04:10 PM 07/13/2000, you wrote:
>Susan;
> >The scientific method only works on that
> >which is directly or indirectly observable.
>
>Bertvan:
>Such as evolution?
Chris
Yes. ". . . directly or *indirectly* observable." Besides, some evolution
*is* directly observable, as you probably know. We can observe genetic
variations and we can observe organisms being killed off by environmental
factors, leaving behind populations that have a *different* total gene pool
than previously, a *different* "median" genome.
Unless someone can show that there is something to *prevent* so-called
"microevolution" from being cumulative (and we can *directly* observe
cumulative variations as well, by *directly* observing that genomes that
resulted from variations can be varied still *more* in subsequent
generations -- something that is observed at *all* levels of life, from
bacteria to the highest primates -- and even in pseudo-life such as viruses.
Further, if there *were* such "barriers" between species in general, or if
there were some rigid "median" for each species, genetic statistics would
absolutely have to be *severely* skewed towards such medians, *regardless*
of environmental factors. Broccoli, cauliflower, and Brussels sprouts
would all be impossible, because they evolved, *within human history*, from
some common ancestor (I don't remember what that ancestor was/is). Right
now, they all have their own "median" genome(s).
In some special cases, there might be a kind of median of some sort that is
unusually stable (if there is a corrective mechanism that keeps the genome
from varying or that corrects the genome in subsequent variations). But
even these are not absolutely stable and rigid. Further, such a mechanism,
if it is *too* "good," will cause the species to go extinct as soon as it
meets conditions that it is not currently adapted to. What Jones and the
rest must show is that there *is* such a rigid mechanism and yet (via pure
logical magic) make it compatible with the fact that there is no observed
*general* severe skewing of genetic statistics around genetic medians
except insofar as the *environment* serves as a *corrective* mechanism,
selecting *out* those genomes that vary too much from the local optimum.
Pleiotropy and genetic cross-linking can *slow* evolution, by requiring, in
some cases that morphological features controlled by one gene become
controlled by separate genes, and that cross-linkages be broken, but there
is no evidence of a *rigid* barrier to macroevolution. Since the ID folks
are not *merely* claiming that they don't believe in macroevolution but are
claiming to *know* that it does not occur, they have the obligation to
carry the burden of proof.
This archive was generated by hypermail 2b29 : Sat Jul 15 2000 - 00:10:54 EDT