> >Programs and self-programming for development
> >---------------------------------------------
> >When we understand the realities of this genetic code, we
> >realize that the codes can be regarded as programs which
> >can be stored in the living cell. These programs in fact
> >amount to an internal self-representation or 'picture' of
> >the structure of the cell itself and of all other types of
> >cell which may come from it during the growth and
> >differentiation of the organism of which it is a part. This
> >concept of living organisms being uniquely different from
> >non-living systems in having internal self-representation
> >raises a point of profound importance.
>
> This is a common "Jurassic Park" model of the genetic code but think
> it is not quite right. I agree with "living organisms being uniquely
> different from non-living systems", but I understand it may not be
> quite accurate to say that the genetic code has "an internal self-
> representation or 'picture' of the structure of the cell itself". I
> understand that the information needed to build a cell is contained not
> only in the genetic code, but in the developing cell's environment (eg.
> neighbouring cells, the mother's body) and even the universe as a
> whole (eg. gravity, light, etc). Indeed, some of the information may
> have come from outside of the universe altogether, eg. by
> supernatural intervention.
>
Yes, the book was written quite a long time ago (1978). There are certainly
other factors at work during development; after as few as three or four
divisions of the zygote, the cells are dividing unevenly, and the resulting
cell mass has an observable orientation; the differing cytoplasm in the
daughter cells affects their subsequent development (I'm not sure of precise
details). It is also true that development is affected by the mother's body;
various teratogens can interfere with normal development (remember thalidomide,
for example, or certain diseases like rubella) and it is also true, I believe,
that normal development may be in some part governed by hormone levels in the
mother's blood. Even so, I think I would be right in saying that these are
influences upon the genome, affecting when the information contained therein
is expressed, and to what extent. Supernatural intervention is certainly
possible, but by its very nature I doubt whether it could be discerned as
such; it would surely appear in the guise of a "natural" process for which
we don't (as yet) have the explanation. One must be wary of a "God of the gaps"
in cases like this.
> GC>This development in the theory of the genetic code implies
> >a biological discovery of immense importance: not only are
> >the processes of life directed by programs, but also in some
> >extraordinary way the living cell produces its own program.
> >Professor Longuett-Higgins sums this up from the biological
> >point of view by saying that it results in the biological
> >concept of the program being something different from the
> >purely physical idea of a program. He says, 'We can now
> >point to an actual programme tape in the heart of the cell,
> >namely the DNA molecule.' Even more remarkable is the fact
> >that the programmed activity in living nature will not merely
> >determine the way in which the organism reacts to its
> >environment: it actually controls the structure of the
> >organism, its replication, and the replication of the
> >programmes themselves. And this is what we really mean when
> >we say that life is not merely programmed activity but self-
> >programmed activity.
>
> Indeed, as Denton points out, the living cell is the only
> example of a self-duplicating Von Neumann machine:
>
> "One of the accomplishments of living systems which is, of course,
> quite without any analogy in the field of our own technology is their
> capacity for self-duplication. With the dawn of the age of computers
> and automation after the Second World War, the theoretical
> possibility of constructing self-replicating automata was considered
> seriously by mathematicians and engineers. Von Neumann discussed
> the problem at great length in his famous book Theory of Self-
> Reproducing Automata, but the practical difficulties of converting the
> dream into reality have proved too daunting. As Von Neumann
> pointed out, the construction of any sort of self-replicating automaton
> would necessitate the solution to three fundamental problems: that of
> storing information; that of duplicating information; and that of
> designing an automatic factory which could be programmed from the
> information store to construct all the other components of the
> machine as well as duplicating itself. The solution to all three
> problems is found in living things and their elucidation has been one
> of the triumphs of modern biology. So efficient is the mechanism of
> information storage and so elegant the mechanism of duplication of
> this remarkable molecule that it is hard to escape the feeling that the
> DNA molecule may be the one and only perfect solution to the twin
> problems of information storage and duplication for self-replicating
> automata." (Denton M., "Evolution: A Theory in Crisis", 1985,
> pp337-338)
>
> The point is that we cannot with our 20th century technology
> and all the power of human intelligence, produce a
> self-duplicating, self-repairing machine. But according to
> materialist-naturalism, the `blind watchmaker' did it!
>
Paley is generally dismissed today, but *I* think his argument was essentially
reasonable (design shows evidence of a designer). So did Thorpe, as I quoted
in my reply to Art. (I assume you will see this, and so will not reproduce the
same thing here.)
> GC>Jacques Monod is as deeply impressed as any other molecular
> >biologist by the appalling problem with which this confronts
> >us in our attempt to account for the production of life (and
> >in its turn, cellular life) from inanimate matter. This
> >happening is now seen as so extremely improbable that its
> >occurrence may indeed have been a unique event, an event
> >of zero probability. Monod does, however, point out that
> >the uniqueness of the genetic code is the presumed result
> >of natural selection.
>
> The problem is that the genetic code is needed *before* there
> can be true "natural selection":
>
> "A review of current thinking on the origin of life problem thus reveals
> a highly unsatisfactory state of affairs. It is straining credulity to
> suppose that the uniquely complex and specific nucleic acid-protein
> system formed spontaneously in a single step, yet the only generally
> accepted organizing principle in biology - natural selection - cannot
> operate until life of some sort gets going." (Davies P., "The Cosmic
> Blueprint", 1995, p120)
>
> GC>Even if we assume this, the
> >extraordinary problem still remains that the genetic code is
> >without any biological function unless and until it is
> >translated, that is unless it leads to the synthesis of
> >the proteins whose structure is laid down by the codes.
> >The machinery by which the cell (or at least the 'non-
> >primitive' cell, which is the only one we know) translates
> >the codes, consists of at least fifty macro-molecular
> >components which are themselves coded in DNA. Thus the code
> >cannot be translated except by using certain products of its
> >translation, the occurrence of which, in the right place and
> >right time, seems overwhelmingly improbable. Sir Karl Popper
> >(1974) comments, 'This constitutes a really baffling circle;
> >a vicious circle, it seems, in any attempt to form a model
> >or theory of the genesis of the code.'
>
> Indeed, it is the ultimate "chicken" and "egg" puzzle. The
> genetic code alone can make life's proteins yet the genetic
> code itself is encoded in protein.
>
>
> Steve
>
Thanks for your comments
/Gary