From: colby@bu-bio.bu.edu (Chris Colby)
Newsgroups: talk.origins
Subject: here we go again (II)
Date: 26 Sep 92 21:10:50 GMT
Organization: animal -- coelomate -- deuterostome

In article <19920924.141504.179@almaden.ibm.com> mannk@fshvmfk1.VNET.IBM.COM writes:
>Robert E. McGrath writes:

>I ask again for observations of macro-evolution happening.

Here is another line of evidence. Evolution predicts that traits
should not show evidence of being designed from scratch -- rather
biological traits should appear to be modified from structures
present on their ancestral species.

I know this (if I include the last post) is a lot of evidence to
digest at once. Please feel free to start discussing any single
topic I have raised and ignore the rest (for know). I personally
think the hierarchical distribution of biological traits is the
best evidence of common ancestry, so maybe we should start there.

In order to reciprocate, please post what you feel is the best
evidence for special creation. Has it been observed? How should
we expect created organisms to differ from evolved ones? In other
words what predictions of creationism (please suppy this theory
if you can as I have been unable to locate any trace of it) differ
from that of evolution? Lets consider both options openly and
side by side. 

-----------------------------------------------------------------

Evidence of modification with descent

	Many organisms show features of appallingly
bad design. This is because evolution via natural selection
cannot construct traits from scratch; new traits must be mod-
ifications of previously existing traits. This is called
historical constraint. A few examples of bad design imposed
by historical constraint:

	In parthenogenetic lizards of the genus _Cnenidophorus_,
only females exist. Fertility in these lizards is increased when
another lizard engages in pseudomale behaviour and attempts to
copulate with the first lizard. These lizards evolved from a sex-
ual species so this behaviour makes some sense. The hormones
for reproduction were likely originally stimulated by sexual
behaviour. Now, although they are parthenogenetic, simulated
sexual behaviour increases fertility. Fake sex in a partheno-
genetic species doesn't sound like good design to me.

	In African locust, the nerve cells that connect to
the wings originate in the abdomen, even though the wings are
in the thorax. This strange "wiring" is the result of the
abdomen nerves being co-opted for use in flight. A good
designer would not have flight nerves travel down the ventral
nerve cord past their target, then backtrack through the
organism to where they are needed. Using more materials than
necessary is not good design.

	In human males, the urethra passes right through the
prostate gland, a gland very prone to infection and subsequent
enlargement. This blocks the urethra and is a very common med-
ical problem in males. Putting a collapsible tube through an
organ that is very likely to expand and block flow in this
tube is not good design. Any moron with half a brain (or less)
could design male "plumbing" better.

	Perhaps one of the most famous examples of how evolution
does not produced designed, but "jury-rigged" traits is the
panda's thumb. If you count the digits on a panda's paw you will
count six. Five curl around and the "thumb" is an opposable digit.
The five fingers are made of the same bones our (humans and 
most other vertabrates) fingers are made of. The thumb is con-
structed by enlarging a few bones that form the wrist in other
species. The muscles that operate it are "rerouted" muscles
present in the hand of vertabrates (see S.J. Gould book "The
Panda's Thumb" for an engaging discussion of this case). Again,
this is not good design.

Chris Colby
email: colby@bu-bio.bu.edu



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