>Studies from comparative molecular biology are NOT consistent
>with the predictions of Darwinism. One observes an almost uniform
>equidistance between the amino acid sequences of any homologous
>protein within any taxonomic group when measured with respect
>to any Outside Taxonomic Unit (OTU). One has only to consult
>the Dayhoff Altas of Protein Function and Structure to see this.
>Motoo Kimura explained this phenomenon within the Darwinist
>paradigm by suggesting that most genetic mutations are neutral
>and that an organism that has remained morphologically unchanged
>for a long period of time has undergone just as much genetic
>mutation as all other lines of descent regardless of the amount
>of adaptive transformation. This is known as the molecular clock
>hypothesis and it is not a result of any PREDICTION of Darwinism.
>It is an attempt to salvage Darwinism from potential falsification
>by suggesting (without any confirming data) that the molecular
>differences along all adaptive radiations from a common phylogenetic
>branching point converged sometime in the distant past.
>In the words of Michael Denton:
>
>"Rather then being a true explanation, the hypothesis of the molecular
>clock is really a tautology, no more than a restatement of the fact that
>at the molecular level the representatives of any one class are equally
>isolated from the representatives of another class....
>
>[I]f evolution is true then, yes indeed, the clock hypothesis must also
>be true. Again the hypothesis gets us nowhere. We save evolution
>because we believed it in the first place."
>_Evolution: A Theory in Crisis_ pg 296.
>
>The molecular clock hypothesis was not an a-priori prediction of
>Darwinism. It was an a-postiori repair to save Darwinism from
>falsification.
The prediction that Loren described is not the molecular clock. Molecular
clocks only work when you put some sort of time scale on them. The
prediction that Loren gives has only to do with sequence comparisons and I
believe that his assertion remains: sequences from organisms more closely
related in evolution ought to be more similar to each other and the nested
tree obtained by sequence comparisons ought to reflect the actual
phylogeny. [the data are consistent with evolution]
I do not at all consider the Kimura modification to be an a-posteriori
repair to save Darwinism from falsification. It is a correction to an
erroneous idea that neutral drift would not/could not occur. In fact, once
you recognize that neutral drift is to be expected (and given our knowledge
of replication, translation, and mutation this is obvious in my opinion),
the equidistance to outside taxonomic groups is to be expected and is
entirely consistent with common ancestry. Those who oppose this
interpretation seem to think, for example, that modern fish sequences ought
to look identical to the ancestral fish as if mutations of modern fish
genomes did not occur in the intervening millenia. This seems obviously
false to me. [Note that we still are not talking about molecular clock
here. The clock hypothesis flows out of the equidistance observation
because when we plot distance vs. estimated time of divergence we get a
more or less constant rate.]
I think that Denton is dead-wrong on this and that those who follow him
e.g. _Of Pandas and People_ are also dead wrong. Equidistance is
confirmatory of common ancestry and rather than disconfirmatory.
Interestingly for you Denton fans out there, the hierarchical clusters that
he shows are simply phylogenetic trees (or cladograms for you
precisionists) viewed from the top down. You can derive the same results
about equidistance from those diagrams as you can from the conventional
branching representations.
In _Biochemistry_ by Voet and Voet there is a discussion of sequence
comparisons and evolutionary implications drawn from them that is very good
in my opinion.
Following this message I will send to the group an on-line mini-lecture
that I sent to my biochem students this semester.
Terry G.
_____________________________________________________________
Terry M. Gray, Ph.D. Department of Chemistry and Biochemistry
Calvin College 3201 Burton SE Grand Rapids, MI 40546
Office: (616) 957-7187 FAX: (616) 957-6501
Email: grayt@calvin.edu http://www.calvin.edu/~grayt