From: Keith Henson (hkhenson@rogers.com)
Date: Tue 10 Jun 2003 - 12:14:35 GMT
At 10:31 AM 09/06/03 -0700, Dace wrote:
> > From: Keith Henson <hkhenson@rogers.com>
snip
> > A definition is just that. Not an answer, not an explanation. The
> > definition most researchers/writers in the field use is 1) most congruent
> > with the common features of genes and computer viruses 2) simple 3) leads
> > to predictions that are not (to my knowledge) violated.
>
>An incorrect definition, no matter how simple, is not only unhelpful but
>downright harmful.
Please demonstrate with examples how the definition of memes as replicating
information is incorrect and fails the similarity test of extracting the
significant factors from all the above mentioned replicators.
> > > > It is generally considered that the original pole of the egg is
>determined
> > > > by an external factor. Morphogenesis is now thought to rely on
>chemical
> > > > gradients, which sequentially (head to tail, front to back) activated
>hox
> > > > regulator genes.
> > >
> > >Coen goes into a lot of detail on this, but even he agrees this is not a
> > >final answer. What, then, determines the chemical gradients?
> >
> > Ultimately geometry. Any point on a sphere (the egg) identifies an
> > axis. The body plan, head to tail is along that axis. Cells at the point
> > produce the first gradient chemical, diffusion establishes the
> > gradient. One other point on the equator, even a random point, is enough
> > to produce the left/right and back to front axes.
>
>Interesting response. That geometry ultimately determines bodily form is
>precisely why Paul Weiss (and others) proposed the concept of morphogenetic
>fields. The whole point of a field is that it's spatial rather than
>material.
The term "Morphogenetic field" seems to be rather abused. Of the first ten
Google responses, only the first
"Quantum Gravity: String, Weave or Morphogenetic Field?" is really about
what would normally be called non-material fields. Numbers 2 ,3, 4, 5 are
New Age drivel, including Sheldrake #9. Three seem to be about
embryology. Here is a quote from #10. www.devbio.com/chap03/link0305.shtml
"In some areas of developmental biology, the concept of the field had
persisted, and the notions of limb fields and heart fields are still in the
literature (see Sater and Jacobson, 1990; Easton et al., 1994; , Cohn et
al., 1995). In such instances, no claims are usually made other than that
these areas of mesoderm are destined to form these particular structures.
In recent years, several developmental biologists have revitalized the
ideas of fields and have reclaimed their fundamental importance for both
development and evolution. De Robertis and his associates (1991)
synthesized molecular and classical material "to increase awareness among
modern developmental biologists of the old concepts of morphogenetic
gradient fields." At that time, however, the interactions between parts of
any field were still unknown, but De Robertis et al (1991) emphasized the
roles that homeobox genes may play in initiating and organizing these
fields. Especially important to them were two observations concerning
gradients produced by Hox proteins in limb buds. The first was that
gradients of these proteins could induce the production of specific
proteins at specific sites, and that these proteins might establish the
conditions for a field (such as the limb field or feather bud field) to
emerge. The second notion was that the gradients of these proteins might
establish the polar axes of these organs. Until recently, the interactions
that constituted these fields could not be identified. However, the
discovery of the homologous pathways of development has given us new
insights into how these fields are established and maintained."
>The question is whether the field is reducible to genes or if it
>exists in the same sense that quantum or electromagnetic fields exist. If
>morphogenetic fields are real, the question becomes whether they are
>produced by timeless "generative equations" (Goodwin) or if they result from
>the influence of past, similar organic forms (Sheldrake). This is how the
>issue looks right now.
"Until recently, the interactions that constituted these fields could not
be identified. However, the discovery of the homologous pathways of
development has given us new insights into how these fields are established
and maintained."
I really wish you would use Google more.
> > Sample articles
> >
> > Reference: Scientific American February 1994 PAGES 58-66
> > Articles Name- The Molecular Architects of Body Design.
> > By William McGinnis and Michael Kuziora
> > Jest of Article- Putting a human gene into a fly may sound like the basis
> > for a science fiction film, but it demonstrates that nearly identical
> > molecular mechanisms define body shapes in all animals.
>
>If the molecular mechanisms are the same, and the organisms are radically
>different, doesn't that demonstrate that organisms are not a product of
>molecular mechanisms? This is a huge problem for the mechanistic theory of
>life.
Hardly. "Body shapes" at the level of having a head to tail, left to right
and front to back are common from insects to elephants and they all start
from a single cell. That the same mechanism (hox genes) lays out the
developmental axis only indicates animals with bilateral symmetry had a
common ancestor.
> > >This is not as off-topic as you might think. As an engineer, you're
> > >predisposed to think about things in terms of mechanics. I'm having
>trouble
> > >getting you to understand organic development due to interference from
>the
> > >machine meme. In other words, a meme which has *replicated* in your mind
> > >is preventing a simple piece of nonmemetic information from being *re-
> > >created* in your mind on the basis of your cognitive capacities.
> >
> > At the root of it, you are attracted to a world with magic. I not only
> > understand that, but I can trace out (with Pascal Boyer's help) why human
> > minds were shaped by evolution in a way that makes such propensities
> > common. There is no magic and I regret that. (My mind--no less than
> > yours--was shaped to find magic attractive.)
> >
> > Still, there is no doubt in my mind (or anyone else who is well grounded
>in
> > the sciences) that the universe is based ultimately on physics and the
> > chemistry of matter.
>
>This is simply not the case. I'm not the only person well grounded in the
>sciences who rejects the reductionist view. The holistic view is not based
>on a predilection for magical thinking but a recognition of the facts.
I see nothing wrong with a "holistic view." For example, stellar physics
is ultimately connected to the emergence of life in a dozen ways. But in
my experience, people who *use* the term usually have a very poor grasp of
the facts and will not research them.
It isn't quite as bad as scientologists who simply cannot comprehend the
need for double blind experiments. Their minds completely reject the
concept that humans can fool themselves.
> > That does not keep the universe from being vastly complicated and
>endlessly
> > interesting. Simple math generates the bewildering complexity of the
> > Mandelbrot. Simple chemistry and evolution has generated a vast and
> > fascinating biology--one consequence of which leads to topic of this
> > mailing list.
> >
> > The root of biology, DNA and proteins, *is* mechanical as anyone who has
> > followed developments in this area over the last 50 years should know. (I
> > started reading Scientific American almost 50 years ago.) One of the
> > enzymes for making ATP is known (by direct observation) to rotate.
>
>The mechanics of protein-formation are still not known, and it's not at all
>clear that protein-formation, particularly at the quaternary level, is
>forced into place by purely chemical and mechanical factors.
I would say rather that the mechanics of protein formation are *extremely*
well known. Put "protein synthesis" in Google and see for yourself. We
may not know every detail, but we know a heck of a lot.
I don't exactly know what you are talking about as "quaternary level." If
you are talking about protein folding, one of the screen saver number
crunching programs being run on spare person computer cycles assumes purely
chemical and mechanical factors. Put "protein folding" in Google. The
fifth link is http://www.stanford.edu/group/pandegroup/folding/
>Keep in mind
>that organisms, at the molecular level, are highly chaotic. Molecular
>structures are in continual flux. They are constantly being torn down and
>rebuilt, and the result is always completely novel. Even identical twins
>bear no relation to each other at the molecular level. Life follows the
>principle of microindeterminacy coupled with macrodeterminacy (in the words
>of Paul Weiss).
That's true, even in the case of C. elegans with exactly 959 cells.
>While the activities of molecules in cells are
>indeterminate and unpredictable, higher levels of structure are determined
>in accord with standard patterns. We see this in embryonic development.
>The first discernible form to appear in the embryo beyond the cell is not
>tissues but the whole body plan. Following this, the embryo develops the
>beginnings of circulatory, nervous, immune and organ systems. These
>outlines are then filled in with organs, but even these exist, at first,
>only as outlines. Finally, organs and limbs are "fleshed out" with tissues.
>If genes build bodies, they should do so step-by-step from the level of
>tissues on up. The actual picture is precisely the opposite. Reduction to
>the molecular level could not be a more inappropriate and misleading model
>for organisms.
See the cites above. Your assertion is just not supported by the
evidence. Cells multiply in the embryo and eventually become committed to
a particular tissue type depending on their particular location in chemical
gradients. This happens several times, generating everything from stripes
on zebras to a particular number of fingers.
>Science is all about generating results that can be replicated.
Oh? Much science is observational only. We have yet to generate a star
much else a universe. But biology generates results that can be replicated
every day of the week.
>The problem
>is that molecular structures in cells are totally novel and cannot be
>replicated. So biologists tend to simply ignore the chaotic reality of life
>at the molecular level, and the result is that the general public gets the
>impression that cells are like factories, with machine-like repeatability of
>its basic operations. Nothing could be further from the truth.
Please tell this to someone with hemophilia.
Keith Henson
===============================================================
This was distributed via the memetics list associated with the
Journal of Memetics - Evolutionary Models of Information Transmission
For information about the journal and the list (e.g. unsubscribing)
see: http://www.cpm.mmu.ac.uk/jom-emit
This archive was generated by hypermail 2.1.5 : Tue 10 Jun 2003 - 12:22:43 GMT