Alu sequences and human evolution

FOSTERCMD fostercmd at aol.com
Tue Jul 19 08:31:04 EST 1994


In article <MAILQUEUE-101.940719103729.256 at molbiol.uct.ac.za>,
ED at molbiol.uct.ac.za ("RYBICKI, ED") writes:

"..Read first, formulate theory later.."

Thank you Dr. Rybicki for your post response.  I agree with some of your
criticism but have a problem with your attitude unless you are attempting
to be humurous.   The primary purpose of the post was to stimulate
thinking on the possible involvement of viruses,( rather than just
classical mutation and natural selection), as a driving force which could
explain the punctuated periods depicted in the fossil record.  Current
cataclysmic theories can explain rapid extinction, but I do not see how
they explain the rapid evolution of many new species ( although I do agree
with the principles of natural selection whereby a dramatic change in
environment or ecological structure can speed the forces of natural
selection using "mutants").  One thought is that the same comets or
asteroids that may have caused extinctions could have also carried new 
"XNA" to earth which could explain the rapid appearances of new "higher
order" traits You are right in pointing out that one postulate does not
require the other, however,  inorder to explain certain periodicities in
the punctuations of evolution I am tying the two ideas together. (ie.
viral role in evolution  connected to the "idea" that some viruses are
carried by comets).
     In regards to the second general idea I have read that :
1.  Studies of the Murchinson meteorite from Australia have shown the
presence of amino acids and nucleotides.
2.  Spectrophotometric studies of Halley's comet showed the presence of
organic molecules.
     I also would like to debate the your comment that PCR techniques
cannot be used on meteorite material because one would not know what sHe
is fishing for.
 Since the genetic code appears to be essentially universal I think that
using a shotgun approach with universally recognized sequences could
potentially amplify any XNA present in a properly prepared meteorite
sample.  The question is; what is the minimum oligonucleotide length
required?
       Any further comments are appreciated.



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