Re: PZ Myers sued for libel

dkomo wrote:

John Harshman wrote:


dkomo wrote:



John Harshman wrote:



dkomo wrote:


[There's something wrong with the way your newsreader is quoting below,
and it screws up the attributions. What happened?]



Dunno. The quoting tree in my post of 8/21/2007 9:53PM -- the most
recent one you replied to -- was okay. But when I opened up your reply,
the tree was hosed. I haven't noticed that my newsreader has had any
problems before.

I'd start trimming some stuff, but I'm in hurry tonight.


PZ Myers, a developmental biologist, writes:

"As I mentioned before in my review of Stuart Pivar's LifeCode: The
Theory of Biological Self Organization, I'm actually sympathetic to the
ideas of developmental structuralism. This is the concept that physical,
mechanical, and chemical properties make a significant and
underappreciated contribution to the acquisition of organismal form;
genes are not enough, do not carry a complete specification, and what we
have to consider is interactions between genes, environment, and
cytoplasm. Good stuff, all of it — and I'd like to see more work done on
the subject."

http://scienceblogs.com/pharyngula/2007/07/lifecode_from_egg_to_embryo_by.php

To which I say, "Right on!" It's time biology stopped considering the
the theories of complexity and self-organization as the crazy aunt in
the attic.

Read again: "...genes are not enough, do not carry a complete
specification..."


Ho hum. This is hardly an endorsement of magical self-organization. If I
understand Meiurrs here, he's merely talking about the physical
properties of materials and their interactions in development -- how
sticky cells are, whether they tend to flatten against surfaces or
become round, greater cell division rates on the right side of a long
structure curving it to the left, and so on.

Genes are expressed in the environment of a cell and the cell's
surroundings. Obviously development works through those. But the
differences between species are still due to differences in their genomes.

Is the spherical shape of many cells an example of self-organization, or
do you think that they are spherical because of natural selection? Does
the cell's DNA program it to be spherical?


None of the above. Is the spherical shape of a drop of water an example
of self-organization? If so, the term seems not to be a very interesting
one.


For me the set of self-organizing systems is a fuzzy set. It covers a
continuum of examples from the simplest atom -- hydrogen -- to the most
complex living organisms. The question isn't simply whether something
is or is not self-organizing -- the classical world of hard-edged
categories -- but the *degree* to which it is. So the degree to which a
hydrogen atom is self-organizing is lower than the degree to which a
drop of water is. Why? Because the hydrogen atom consists of a small
number of simple components -- an electron and proton -- whereas the
drop of water consists of a very large number of more complex components
-- water molecules.

The theory of self-organizing systems is a work in progress, and the
definition at present is not sharp:

"Self-organization, despite its intuitive simplicity as a concept, has
proven notoriously difficult to define and pin down formally or
mathematically, and it is entirely possible that any precise definition
might not include all the phenomena to which the label has been applied."

http://en.wikipedia.org/wiki/Self-organization

So I prefer to view self-organization as being distributed throughout
nature to a greater or lesser degree depending upon each particular
example of it.


All of which communicates nearly nothing to me.


The theory of self-organizing systems is like that.


Now in fact the shapes of cells are the result of the physics of



their materials, and those materials are generally the way they are
because natural selection has resulted in such a shape, by whatever
proximate mechanism.

Permit me to demur. Regardless of your views vis-a-vis
self-organization, your statement is just plain wrong even in the
rigidly constrained world of classical evolutionary theory. That's
because there is such a thing as genetic drift and neutral alleles, and
because many of the phenotypic features of organisms are "accidental"
and have no adaptive significance.


Permit me to demur too. I don't think that all that many phenotypic
features have no adaptive significance. At any rate this seems
irrelevant to our argument.



If shapes of cells and simple organisms have no adaptive significance,
that's a point in favor of self-organization versus evolution.


A sphere may be the default shape for a cell -- the



one that simple surface tension produces in a blob of liquid -- but
since cells take many shapes, it seems that a spherical shape, or any
other, would be maintained by selection that prevented it from gaining
the physical characteristics that would make it assume any of those
other shapes.

It's just as likely that selection plays no role at all in maintaining
these shapes.


Is it your position that the shapes of cells never have anything to do
with selection?

No, I'm not saying that. I'm saying that there are many examples where
the shapes have little to do with selection. Do you have a copy of
Dawkins' _Climbing Mount Improbable_? In the chapter "Kaleidoscopic
Embryos", there is a page of etchings from Haeckel of diatoms -- single
celled plants -- which illustrate 2, 3, 4, 5-fold and higher symmetries.
The shapes of these cells are awesomely intricate and each is
completely different from all the others, almost like snowflakes. A
glance at this page should convince anybody that these cell shapes have
little to do with adaptation. They are constructed by a "higher"
principle -- self-organization.

Well, technically those aren't cells. They're little glass cases the
cells build for themselves. In fact the shapes do have *something* to do
with selection. Some of them build little spines to deter predation,
other shapes differ between pelagic and benthic forms, etc. I would say
that physical principles influence shape, and that selection is neither
all-powerful (some shapes may not be easily reachable) nor
all-scrutinizing (some shapes may be equally good in an environment, and
thus may be subject to drift). How you can know that self-organization,
whatever you mean by that, is involved just by glancing at the shapes is
not clear to me.

Dawkins also shows illustrations of Radiolaria, another plankton group.
These also have fantastic skeletal shapes with high degrees of
symmetry.

And much of the symmetry is probably due to the same sorts of causes
that make crystals symmetrical: similar causes acting in different parts
of the object. Would you call crystal formation "self-organization"? It
seems a flexible term.

Dawkins writes about one of these:

"The kalaiedoscopic masterpiece in Figure 7.6 might have been designed
by the visionary architect Buckminster Fuller (whom I was once
privileged to hear, in his nineties, lecturing for a mesmerizing three
hours without respite). Like his geodesic domes it relies for its
strength on the structurally robust geometric form of the
triangle...Indeed D'Arcy Thompson, whom we met in connection with snail
shells, would have argued that the embryologies of these exquisite
Radiolarians have more in common with the growth of crystals than with
embryonic development in the normal sense."

By the way, it would do a world of good for your arguments and
understanding of the matter if you would read D'Arcy Thompson. Have you?

I hope you can distinguish between the physical mechanism



of shape production and the evolutionary reason why a cell would take
any particular shape.


I hope you can also. That's what this debate is about -- how much of
what we see of living organisms is due to self-organization and how much
is due to evolution. I suspect you are a closet panadaptationist. Are you?


I'm not a closet anything as far as I know. I think that most of the
interesting features of organisms are adaptations. (Though some of these
adaptations, particularly those acted on by sexual selection, are
arbitrary.) Now, since "self-organization" doesn't seem to have any
coherent meaning, I am unable to discern what I should think is due to
it and what isn't. Nor do I see any need for a dichotomy here. The
nature of any self-organization presumably depends on the components of
the system, and these can be provided through evolution. That is, any
self-organizing system can be fine-tuned by selection, and can owe its
existence to selection. It's unclear just what you are talking about.

I repeat once more that the differences between species are due to
differences in their genomes. Do you disagree?

I can agree that *most* (and I'm sure exactly how much) of the
*differences* between species is due to differences in their genomes.


Can you give an example of a difference that isn't?

I assume that the answer is no, for the present at least.

But this has little to do with what I consider is the central question:
how do living things get from point A to point B, point A being the
genome, and point B the immense complexity of structure and function
which is a living organism. I see a huge chasm between point A and
point B, and I think that chasm will eventually be shown to be filled
with a vast variety of self-organizing processes which are to a degree
independent of evolution.


And I think you have confused development with evolution. Development is
not evolution. What it means for a developmental process to be
independent of evolution is unclear to me. I don't know what you're
arguing for, and I don't know what you're arguing against.

Alas, I'm out of time. Will reply to the paragraphs immediately above a
little later. I don't want to rush past these with only some sound bites.

Ah, so perhaps the answer is merely that you haven't had time to list
your examples.

.

Relevant Pages

  • Re: PZ Myers sued for libel
    ... It's time biology stopped considering the the theories of complexity and self-organization as the crazy aunt in the attic. ... because natural selection has resulted in such a shape, ... If shapes of cells and simple organisms have no adaptive significance, that's a point in favor of self-organization versus evolution. ...
    (talk.origins)
  • Re: PZ Myers sued for libel
    ... considering the the theories of complexity and self-organization ... Is the spherical shape of many cells an example of ... If shapes of cells and simple organisms have no adaptive significance, ... that's a point in favor of self-organization versus evolution. ...
    (talk.origins)
  • Re: PZ Myers sued for libel
    ... of self-organization? ... because natural selection has resulted in such a shape, ... If shapes of cells and simple organisms have no adaptive significance, ...
    (talk.origins)
  • Re: Whats more important, self-organzation or evolution?
    ... assemble is, itself, the result of selection and evolution. ... self-organization but that capability we see in modern cells results ... Self-organization is universal. ...
    (talk.origins)
  • RE: Identify shape in cell
    ... First shapes are not in cells but onto of ... For Each shp In ActiveSheet.Shapes ... The problem then becomes which cell is closest to these shapes. ... How can I take the current selection and determine just what shape is ...
    (microsoft.public.excel.programming)