Subject: On influencing factors
Date: Tue, 27 Oct 98 15:14:27 -0600
From: Mark Mills <mmills@fastlane.net>
To: "Memetics List" <memetics@mmu.ac.uk>
Message-Id: <E0zYGPd-000406-00@dryctnath.mmu.ac.uk>
Derek,
This has been on my mind for a few days, so I thought I'd continue our
conversation. The comments seemed general, so I am posting it to the
list.
>>As far as I know, there is nothing in DNA sequences which we can link
>>to cell differentiation. Am I missing something?
>Well, the discipline of molecular embryology is base entirely on the
>idea that differential gene expression is the controlling factor in
>embryogenesis. A direct demonstration of this is what won
>Christine Nusslein-Volhard and Eric Wieschaus the Noble Prize in 1996.
Well, I won't hide my ignorance. I appreciate your reading
recommendations. I will change my position from 100% of cellular
differentiation controlled by non-DNA structures, to a fractal mix of
internal (DNA) and external control.
This doesn't change my argument regarding memes. My interest in memes is
cybernetic or control system focused. I am wondering how much 'control'
comes from DNA and how much comes from 'outside' the nucleus.
As far as I can tell, the common dogma suggests the nucleus 'controls'
itself. In the minds of many, the nucleus 'thinks' for itself. Control
is made sensible by putting the homunculus in the nucleus and letting it
'think for itself.'
I will admit that a great deal of control is exerted by the nucleus, but
question how complete it is. It seems clear that many examples of
'outside' influences exist.
To quote your above comment, 'differential gene expression is the
controlling factor,' sounds like a claim that 100% of control goes to the
nucleus.
I am just guessing. Perhaps you can clarify your position.
Do you mean 100% control resides in the DNA?
Do you suggest outside influences are immaterial to cellular
differentiation?
I remain skeptical. I've read about DNA/RNA clock systems tied to
circadian rhythms. I've seen many 'protein distribution' maps showing
cells apparently work together to spread specific protein production out
over the entire organism, but leave the work to only a limited set of
cells.
If both cellular rhythms and protein production can be influenced by
forces outside the cell, how clearly can we draw the boundary between
what is controlled by DNA vs 'the outside.'
I think this an important for memetics. Memetics claims to be involved
with a second sort of 'control code,' something outside the nucleus. I
suspect we argue a great deal regarding where to place the code due to
our concept of the role DNA plays.
As best I can tell, you place the code (non-DNA-genotype) in the
environment. The exhibition (non-DNA-phenotype) is expressed in behavior
of humans.
I sense you place the code outside the body because of your high
confidence in genetics to explain everything the body does, outside of
conscious thought.
I take the view that DNA is not 100% in control. My fractal split
between 'internal control' and 'external control' (instinct vs.
environment) goes down to even cellular processes. Even at the cellular
level, there are organizational choices that must be made between the
demands of 'outside' factors and DNA control systems.
Since I don't posit 100% control in the DNA system, I have no problem
putting the second control system in the body with DNA. I simply put it
at a different organizational level. I suggest genetics is a
intracellular control system, while memetics (the second control system)
works at the tissue level. Both control systems are in balance with
outside forces.
The other ingredient to add to the puzzle is self-organizing features of
auto-catalytic protein systems (see Kauffman). I bring this up to replace
the homunculus. If we admit the role of self-organization, the
homunculus is serves no purpose.
To conclude, I'll admit to being out of touch with recent discoveries in
the genetics of cellular differentiation. I will continue to argue that
DNA is not 100% in charge, though.
Agreement on this subject would contribute to a consensus regarding the
definition of 'meme' and a location for memetic activity.
Mark
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