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From: mrh@cybvax0.UUCP (Mike Huybensz)
Newsgroups: net.origins
Subject: Re: Prediction or Observation?
Message-ID: <553@cybvax0.UUCP>
Date: Tue, 28-May-85 13:58:35 EDT
Article-I.D.: cybvax0.553
Posted: Tue May 28 13:58:35 1985
Date-Received: Thu, 30-May-85 06:41:33 EDT
References: <1125@uwmacc.UUCP>
Reply-To: mrh@cybvax0.UUCP (Mike Huybensz)
Distribution: net
Organization: Cybermation, Inc., Cambridge, MA
Lines: 80
Summary: 

In article <1125@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes:
> Would you genuninely expect that if all life were created, that
> randomly chosen organisms would share just as many biochemical
> similarities as species sharing many common physical characteristics?

Why not?

> One doesn't need creation OR evolution to predict that organisms which
> are physically similar are going to be more biochemically alike than
> organisms which are physically dissimilar.  I suspect that most people
> would predict this intuitively.

How similar?  In what compounds?  Why should some portions of the
biochemistry be conservative while others vary a great deal?

> Investigation of the rates of change of protein and nucleotide
> sequences (e.g., Wilson et al) finds that the rates are basically
> constant, in contrast to the non-constant rate of morphological
> evolution.  This has certain implications for our topic.

Investigation of HOMOLOGOUS proteins and nucleotides sequences reveals
basically constant rates.  But different rates for different sets of
homologues.

On the other hand, rates of morphological evolution are extremely hard to
characterize because of anthropocentrism.  Take your leopard frog, for
example.  There are at least four species on the east coast that are
"morpologically identical" as far as our senses are concerned: enhance our
senses and we can perceive the differences.  The species were distinguished
by sonograms of their mating calls, as well as hybrid inviability.

> [3p616]  "Molecular evolutionists were slow to recognize this surpising
> and intriguing fact.  They had assumed that organismal evolution
> depends on sequence evolution in proteins and expected a simple
> relationship between two types of evolution.  In particular it was
> expected that morphologically conservative organisms should have
> experienced slower macromolecular evolution than organisms that had
> evolved unusually rapidly at the morphological level.  To date,
> however, there is no convincing evidence that the proteins or nucleic
> acids of conservative creatures are conservative in regard to their
> amino acid or nucleotide sequences."
>
> As an example, frogs and placental mammals may be compared.  All of the
> thousands of species of frogs are placed within a single order, due to
> their high degree of phenotypic similarity.  Placental mammals, on the
> other hand, are categorized into about 16 orders.  Evolutionarily,
> frogs are much older than mammals; obviously morphological evolution
> must have been much slower.  Yet at the sequence level, rate of
> evolution is about the same as that of mammals.
> 
> "Species of frogs that are similar enough to be included within a
> single genus can differ as much at the sequence level as does a bat
> from a whale." [p618]
> 
> Would you predict these sorts of things from evolution?  Would you
> predict it from creation?

Note now that this provides evolutionists a way to predict the magnitude
of biochemical differences within groups depending on their evolutionary
conservatism as shown by the fossil record.  Creationists CANNOT make those
predictions because they cannot identify conservatism because they cannot
measure ages of groups.

> Bacteria (prokaryotes) do not differ much from each other
> morphologically.  But *within* the Rhodospirillaceae bacteria family,
> greater variability of cytochrome _c_ is found than *among* all
> eukaryotic organisms studied.

Here is a perfect example of the inadequacy of morphological criteria for
classification.  There are many groups where (because of the limitations
of our senses) we have not been able to make good phylogenetic
classifications.  Bacterial, protozoan, and some other classifications
are rife with "garbage bin" groups which are acknowledged not to be
monophyletic, simply because there isn't enough data to classify them
any more specifically (yet.)  So there are really two possible explanations
for cytochrome variability among Rhodospirillaceae: that the group is
good but very ancient, or that the group is polyphyletic.
-- 

Mike Huybensz		...decvax!genrad!mit-eddie!cybvax0!mrh