Reciprocating Bill
Posts: 4265
Joined: Oct. 2006
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| Quote (Henry J @ Sep. 09 2007,23:44) | Re "The hypothesis might be true if modern organisms had recoverable front loading DNA, but even then it could have been caused by horizontal gene flow."
I'd think that with front loading, one would expect a much higher quantity of apparent horizontal transfer than would be expected without it.
Henry |
Fair use permits quotation for the purposes of discussion within a scientific audience:
| Quote | Here I propose a hypothesis that answers the questions posed
above, and offers experimentally testable predictions. This hypoth-
esis postulates that (1) shortly (in geological terms) before Cambrian
period a Universal Genome that encodes all major developmental
programs essential for every phylum of Metazoa emerged in a unicel-
lular or a primitive multicellular organism; (2) The Metazoan phyla,
all having similar genomes, are nonetheless so distinct because they
utilize specific combinations of developmental programs. In other
words, in spite of a high similarity of the genomes in phyla X and
Y, an organism belonging to phylum X expresses a specific set of
active developmental programs, while an organism belonging to a
different phylum Y has a distinct set of “working” programs specific
for phyla Y….
There are two main testable predictions of the presented hypoth-
esis, which are absolutely critical for validation of the model:
(1) full or parts of the developmental programs characteristic to
higher taxons must be encoded in genomes of lower taxons, and
(2) blocks of genetic information encoding these developmental
programs in more primitive taxons must be useless in these taxons…
As a general approach to searching for such latent developmental
programs one can effectively utilize information from genome
projects. Accordingly, one may identify genes responsible for an
un-expressed developmental program in a genome of an organism
belonging to a lower taxon, and try to activate it. For example, as
mentioned above, the sea urchin genome encodes a large set of genes
involved in the eye development. It is possible that overproduction of
the active master switch Pax6 in sea urchin may initiate eye develop-
ment. Similarly, since major components of the adaptive immunity
are encoded in the sea urchin genome, one could attempt to activate
production of antibodies by experimenting with transcription factors
or teratogenes.
Another indication that latent developmental program is present
in a lower taxon would be expression of such a program in higher
taxons derived from the lower one in a seemingly convergent
processes. For example, a possible experiment would be to activate
development of circulation systems of mammalian or bird types in
lizards, or even in Xenopus. The circulation systems in mammals
and birds appear to be very similar, however, they developed from
the Reptilian system independently in these taxons. Therefore, it
seems likely that Reptilia possess the program of development of the
circulation system of the mammalian/bird type and requires only a
minor switch to activate it. |
Of course, if it a developmental program for a given structure (such as a camera eye) could be activated within an organism that neither has eyes nor has ancestors that have camera eyes, THAT would be a major problem for contemporary evolutionary models.
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Myth: Something that never was true, and always will be.
"The truth will set you free. But not until it is finished with you."
- David Foster Wallace
"Here’s a clue. Snarky banalities are not a substitute for saying something intelligent. Write that down."
- Barry Arrington
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