Re: [BULK] - Re: Is evolution really the central theory for all of biology?

From: <douglas.hayworth@perbio.com>
Date: Tue Sep 20 2005 - 08:58:02 EDT

The massive and detailed convergence in biology was a surprise for, not a
prediction of, evolution. Nor do there exist unambiguous ways to
distinguish
homologies from analogies. Ultimately it is both subjective and circular.
Subjective because the evolutionist must draw from a variety of criteria to

decide how make his judgement. Circular because he must assume evolution
occurred. Without first assuming evolution, then the evolutionist would
have
to reckon with all the negative evidence which is being ignored.

Cornelius,

BTW, what is a convergence at one "level" is often a homology at another
"level". For example, the physical structure we call the eye is a
well-known example of convergence. The structure was built up several
independent times in evolutionary history. However, there is evidence that
the basic genes that make eyes (photosensitivity) possible are homologous,
i.e., that the genes were present in the common ancestor of flies,
vertebrates and mollosks. So the genetic propensity was always present, as
was the selective advantage of vision in a world illuminated by light. Put
those two together and you would EXPECT convergence. As I said before, some
level of convergence is a prediction of evolution, not a surprise. The
comparative method is sufficiently robust to enable us to be very confident
in characterizing most complex homology/convergence cases, but the context
of level (e.g., morphology vs. genetic basis as well as phylogenetic level)
is important to specify (usually the level is clearly understood by the
context of the character being discussed).

Douglas
Received on Tue Sep 20 09:01:12 2005

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