Re: Sequence Homology

Arthur V. Chadwick (
Wed, 17 Dec 1997 09:13:01 -0800

At 05:09 PM 12/16/97 -0500, Lorne wrote:

>The widespread perception is that the nested homologies go *way beyond*
>what is necessary for "common function." That perception isn't created
>by any one knock-down drag-out example (although pseudogenes come as
>close as anything). The perception is created by reading _Nature_ and
>_Science_ (and, if you're really a glutton for punishment, _Cell_ and
>_Journal of Molecular Biology_) for several years and seeing one gene
>after another after another sequenced, its homologies compared to other
>species, and its sequence/structure/function dissected apart. So if one
>wants to understand and/or challenge the perception that nested
>homologies go way beyond the functional needs, there is, for now, no
>shortcut; one needs to dive into the research journals.

Why do I need to challenge the "perception"? I do not expect scientists
who are not considering other options than evolutionary origin of diversity
to even give consideration to other possibilities. And I know that you,
Lorne are not arrogant enough to suggest this is the only possibility, and
that what evolutionary scientists perceive as the only rational explanation
may only be a reflection of the numbing down of the mind which will look at
only one option. What other possible explanations can you think of outside
of this paradigm? It is not difficult to conceive of others that equally
satisfy the data.

>>The same logic applies to
>>virtually all of the molecular complexity recognized in modern organisms,
>>including the developmental genes and the general scheme of development
>>shared by insects and man. Since morphological change is now clearly
>>recognized as a manifestation of the variable expression of the underlying
>>developmental genes and the molecular complexity shared by all organisms,
>>it is not difficult to see that essentially all evolution of shared
>>molecular complexity is required to have occurred in the Precambrian before
>>there was any record of anything more complex than a carbonized film of
>>single cells.
>Also true. I find it suggestive that while the Precambrian fossils are
>dated about 0.7 billion years old, first life fossils are dated more
>than 3 billion years before that. It looks like God wasn't in a rush to
>create the molecular complexity required for multi-cellular
>morphological diversification.

But if you recognize that all of the complexity of metazoan life forms
preceded the appearance of the forms themselves, what origin do you
postulate for the complexity? To state the question another way, the
complex mechanisms for formation of the eye preceded the first fossil
evidence for an eye by whatever time frame one wishes to apply, lets say a
billion years, since the ancestor of the protostomes and deuterostomes
already had all the stuff to make an eye (if you assume the evolutionary
hypothesis). And the complexity of the eukaryotic cell, including the
incredibly complex structures of the chromosome, are shared by all
eukaryotes, and this pushes back the existence of all this complexity to
the limits of time. And it is of more than passing interest that for
example the histones involved in chromosomal condensation are essentially
identical across the entire spectrum of organisms, such that for example
the histone h3 of a garden pea and a human differ in only a couple of amino
acids. Then there are the scaffolding proteins required to assemble the
histones into nucleosome cores that had to be there before the histones
could function, etc. What mechanism can you propose that would yield such
complex systems in perfectly functional forms billions of years ago such
that only minimal additional changes were required to equip them for
functionality across the entire spectrum of organisms. There are no nested
hierarchies in histone proteins....

>> I do not see how this differs in scientific value from
>>saying that a Creator did it. At least in the latter case we have an
>>intellectually plausible scenario.
when I consider how the
>Creator's natural laws make possible the evolutionary development, from
>simple hydrogen and helium, of stars, heavy elements, planets, oceans,
>atmospheres, and even simple biological molecules on spaceborn hunks of
>rock and ice;

That is an assumption on your part that at least I do not share, since I
know no natural law that could accomplish that, although I wait to be
instructed, if you kniow such a law.

Have a great holiday season and new year!