Re: [asa] Advice for conversing with YECs (Cheek turning)

> Third, I do not *insist*, but simply believe that it is most consistent with
> the evidence. If you can show me (and CD doesn't convince me) that the
> process from cyanobacteria to man occurred by only the natural processes
> that God set in motion with the creation of the first life, I *will* be
> convinced.

From my study of evolutionary biology (MS and PhD in paleontology but
doing a lot with DNA, too), the evidence all looks as though God did
pretty much use biological evolution as the way to create new
organisms, rather than any intervention-style action. I don't have an
a priori objection to intervention-style action, but I do think there
are good theological reasons to think it is unlikely to be common, as
well as the empirical evidence.

> you have faith that the Cambrian explosion is consistent with random
> mutation/natural selection, when it clearly is not

As an invertebrate paleontologist, I think it looks pretty consistent
with random mutation and natural selection. It's worth noting, too,
that Simon Conway Morris, one of the top experts on the Cambrian
radiation, was a featured speaker at the joint ASA-Christians in
Science meeting in Edinburgh-he's not promoting an atheistic agenda,
no matter what Dembski says abotu his books. Perspectives on an
Evolving Creation has a chapter on this; as a co-author of the chapter
my comments would obviously not diverge much from it, though I would
note a few new ideas and discoveries. Ironically, the claim that the
Cambrian poses a big problem for evolution is based largely on Gould's
popularization of it, where he was trying to claim that the Cambrian
radiation pointed to randomness. Gould overdid the randomness claim
(though this is in part hindsight based on subsequent data), though
it's still a very interesting time to study.

> convergent evolution is consistent with random mutation/natural selection
> when it clearly is not

How can it not be consistent? Convergent evolution is to be expected
if evolution happens. A squid, a fish, an ichthyosaur, a turtle, a
penguin, a plesiosaur, a whale all experience the same physical forces
when they try to swim fast. Similar streamlining will benefit each of
them, though the differences in details point to separate evolutionary
origins. All of those except the squid also start with a basically
similar skeleton, etc, making convergence perhaps even more likely.

DNA has only four bases to choose from, so two random sequences will
have about 25% similarity. Some random convergences are quite likely.
 Certain molecules or submolecular features are good for certain
functions or conditions, making convergence due to natural selection
likely. An example is the high proportion of G and C relative to A
and T in organisms living at very high temperatures. The three G-C
hydrogen bonds are stronger than the two A-T bonds, so if possible
increasing the use of G and C will be favored for living in hot
springs, etc. A more subtle but potentially misleading version of
this (especially with few sequences) is that different DNA regions
have somewhat different base usage biases. If a gene gets moved to a
different region with different biases, there can be misleading
patterns.

Bivalves all have no head, two shells, and well-developed gills.
There are a modest number of different things you can do with that and
a lot of bivalves. Convergence and even parallel evolution is a
significant issue, but careful study can sort out a lot.

> steps from bacteria to man are natural, and should be discoverable. It is my
> position, sir, that we should have discovered quite a bit more of them by
> now,

Well, one fossil bacterium often looks a lot like another, so it's not
easy to trace connections there. We do have a very good sequence of
transitional fossils between different groups in those taxa that are
well-studied and that have a good fossil record (such as vertebrates).
 Genetic and other biochemical similarities point to the connections
all the way back to bacteria, but I'm not entirely clear as to what
things you expect to see but don't.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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