Newsgroups: comp.ai.alife
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From: zcaccha@ucl.ac.uk (Christopher Harris)
Subject: Re: Lamarckian Evolution
Message-ID: <1995Feb16.151656.68937@ucl.ac.uk>
Date: Thu, 16 Feb 1995 15:16:56 GMT
References: <3fknbm$bk8@laplace.ee.latrobe.edu.au> <3fn911$53t@fang.dsto.gov.au> <3fvafp$36h@fourier.ee.latrobe.edu.au><3g7jj0$t1s@crl2.crl.com> <66@reservoir.win-uk.net> <3h20d6$gmn@crl.crl.com>
Organization: University College London
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|> Now whether transpons are a mechanism for Lamarkism is a matter
|> of debate.  I can tell you right off the bat that the example
|> given in this thread of giraffes stretching their necks is an
|> oversimplification and vulgarization of his this thought. Philosophically
|> Darwinism tends to refer to gentotype modification through external
|> forces, Lamarckism to refer to a living being modifying itself.  We
|> know for a fact (have known for a generation) that it is a two
|> way street,  events in the cell can alter the genotype, information 
|> can flow from the protein (which is what DNA models) complex to the
|> DNA complex and the DNA can be modified (transposition is changing
|> position,  "jumping genes" is self explanatory).  This is a potential
|> mechanism for Lamarckian (if we mean self modifying) life.  It is
|> there, it has been known and established for over a generation (thats
|> 20 years) and still we have people claiming that there is no
|> known way for a cell to alter the genetic code.  
|> 
|> As for what Barbara McClintock would have said.  She was known to be
|> very open minded and since her little ears of corn were altering
|> themselves,  one thinks she would be especially open minded on
|> this subject.
|> 
|>     - Andrea Chen -

Yes but the point is that self-modifying genotype != Lamarckian evolution.
I would be far more convinced (i.e. far more than zero, which the extent of
my conviction now) if these genotypcial changes were shown to be directly
related to environmental changes or some phenotypical change on the part of
the organism. The Lamarckian stance is that these changes are somehow
purposeful and lead to similar adaptations in the next generation. This in
turn posits some amazing ability to encode ideal responses to environmental
change, and phenotypical changes, into genetic alterations. If we could crack
that, then we wouldn't need alife at all! We would just build our ideal creature
by building up the appropriate genotype.

I don't think people would seek to deny that SOME organisms can modify their 
genotypes - after all, we do it in every germ cell we reproduce - but rather
that these modifications are somehow directed in a useful way. 

Of course, I am willing to be persuaded by evidence, but evidence of that kind
surely would have created a huge media event!

Chris Harris
