"dkomo"  wrote in message
news:car9d9$2lvq$1{at}darwin.ediacara.org...
> Tim Tyler wrote:
> >
> > Here's an essay I wrote recently about life's direction.
> >
> >   http://originoflife.net/direction/
[snip]

> Another oldie-but-goodie from talk.origins 10/12/2003:
>
> howard hershey wrote:
> >
> > dkomo  wrote in message
news:...
> > > howard hershey wrote:
> > > >
> > > > littleblondgirl wrote:
[snip ... this is a partial re-creation of my response.]
> > >
> > > >> On the other hand, those who deny progress could
easily be wrong.
> > >
> > > > No, they cannot.  Where is the pattern of progress?
> > >
> > > The pattern is that the complexity of the *most*
complex organisms in
> > > any time period has been generally increasing over the
past billion
> > > years or so.  This is compatible with the simplistic
model of a random
> > > walk away from a reflecting barrier.  At any given
time you'll have a
> > > spread of organisms with varying complexities, but the
right hand side
> > > of the distribution will move further to the right
with increasing
> > > time.
> >
> > The extent to which this is true is arguable precisely
because we do
> > not have a real (single) metric of 'complexity'.  Gould
used 'size' as
> > a rough substitute metric for 'complexity'.  If you do
that (and size
> > is a pretty reasonable approximation of complexity), I
would think
> > that there might be two points in time at which there
has been a
> > *significant* change in the shape of the curve:  At and
near the start
> > of abiogenesis and at and near the invention of
multicellularity.  But
> > not long (say a few hundred million years) afterward, I
would expect
> > that such a curve would reach a steady-state shape.  The
modal
> > organism in all cases would remain single-celled and
bacteria-like.
> > >
> > > The trouble with this random walk model, attributed to
Gould, is that
> > > it is mathematically equivalent to a diffusion
process, and diffusion
> > > produces a spread away from the origin with a
probability virtually
> > > equally to one.  This implies that growth of
complexity in evolution
> > > is an *inevitability*.  Not even I believe that.
> >
> > Nor do I.  Mostly because I believe that there are
forces acting to
> > *decrease* complexity and that these forces *increase*
in intensity
> > with increasing complexity (forces such as predation by
unicellular
> > rapid growers).
>
> There is one notable exception to this: human knowledge,
which due to
> a feedback effect, is increasing exponentially.  That is,
the more
> complex our knowledge becomes, the faster that complexity
seems to
> increase.  That's why the neurological dimension of
evolution is so
> important.  It's the one area that appears to be still
unbounded.
>
> Of course, you could consider human culture as being
outside the realm
> of biological evolution.  If you look only at the physical
aspects of
> evolution then I think your idea of forces that oppose
increases in
> complexity is valid.
>
> >  IOW, I do not see a completely random walk.  I see a
> > state where it becomes increasingly difficult to get
*more* complex
> > when one is already complex.  This does not prevent
getting more
> > complex, but the conditions have to be just right to do
so.  This
> > would produce a roughly 'steady-state' condition rather
than one in
> > which drift can continue to the right.  This is not a
'barrier' but a
> > softer resistance to flow to the right that become
harder the further
> > to the right one goes.
> >
>
> In Sterelney and Griffith's book _Sex and Death: An
Introduction to
> Philosophy of Biology_ they devote a chapter to discussion
of
> evolutionary progress and growth of complexity.  In that
chapter they
> briefly mention _The Major Transitions in Evolution_ by
Maynard Smith
> and Szathmary. In their conception of life's history,
there are a
> series of major transitions and hence an inherent
directionality.
>
> Sterelney and Griffith write:
>
> "Maynard Smith and Szathmary do not formulate their ideas
in Gould's
> language, but if they did, the difference would be that
they do not
> regard the walls of the graph as fixed over time.  The
major
> transitions in evolution are *movements of the walls.*
Until the
> foundations of eukaryotic life were gradually assembled,
there was a
> right wall, the intrinsic limit on the size and growth and
structural
> complexity of prokaryotes.  In a certain timeless sense -- 
the sense
> in which Gould operates -- the right wall was open, but
for much of
> its history, bacteria evolution was confined within two
walls.
> Similarly, after the evolution of eukaryotes, there was
another shift
> of the right wall, but only a shift.  The invention of the
organism
> required a complex series of evolutionary innovations.
Until these
> came into existence, there was a right boundary to
complexity set by
> the limits on a single eukaryotic cell...Once the
eukaryotic cell
> comes into existence, once sexual reproduction comes into
existence,
> once cellular differentiation comes into existence, the
theatre in
> which the evolutionary drama takes place is changed
irreversibly. The
> boundaries change over time, and mostly in a direction
that increases
> the maximum possible complexity."
>
> So there it is.  Note the word "irreversibly."  In
previous
> discussions of this topic I used the term "complexity's
ratchet."  The
> movement is in general in the direction of increasing
complexity.
> This is also consistent with viewing the complexity graph
as
> *inevitably* diffusing to the right, as any n-body random
walk would
> do.
>
> While there may be some occasional local decreases of
complexity for
> some life forms, mammals do not devolve back to bacteria
because such
> a progression would violate the irreversibility criterion.
>
> > Similarly, there are forces that prevent an already
simple organism
> > from getting simpler (the left-hand wall).
> >
>
> The left wall has also shifted to the left, but only
slightly, because
> of the invention of viruses.  There first had to be
bacteria before
> viruses could emerge.
>
> > > That's as absurd as
> > > claiming there hasn't beeen *any* growth in complexity
over a billion
> > > years and that bacteria are the apex of evolution.
> >
> > There is no apex in evolution.  There is only local
adaptation to
> > local conditions.  Bacteria are not the apex of
evolution.  They are
> > the modal organism.
> > >
>
> I remember the statement in Michael Crichton's _Prey_ that
wherever
> you find bacteria, you also find bacteriophages that prey
on them.
> Perhaps then, phages should be considered the modal
"organism."

I like this approach--and I definitely agree with the
concept of "movable walls." IMO, complexity, when properly
measured (hah!)
increases quantitatively to a limit, then, jumps to a new
window of opportunity, or qualitatively higher
level--windows representing the presence of left and right
walls as opposed to an unbounded right wall. Complexity
continues "progressing" in this hierarchical
manner, possibly without limit. One can look at this as
having a purpose, object, or goal, however I prefer to think
of these terms as only metaphors for the process, namely, a
natural, physical tendency, in its own right.

In considering the entire trend, holistically, I am reminded
that it is very similar to the processes described by Robert
Wright, in his book "Non Zero." In this book, he attempts to
ascribe the general "progress" of human culture over its
entire history to a natural law/tendency to accumulate
"non-zero summness," a games theory concept based on social
cooperative benefits vs competitive ones. He also concludes
there is a increasing positive direction to such overall
complexities, also likely lacking an upper bound, although
admittedly, he presents no precise theory justification or
hard evidence. It is a quite interesting book however, and a
games theory approach may ultimately turn out to
be quite useful in clarifying the many notions of biological
complexity and related questions.         ...tonyC

>     --dkomo{at}cris.com
>
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