On Sun, 18 Apr 2004 21:46:44 +0000 (UTC), jimmenegay{at}sbcglobal.net
(Jim Menegay) wrote:

>r norman  wrote in message
news:...
>> On Sat, 17 Apr 2004 04:29:51 +0000 (UTC), jimmenegay{at}sbcglobal.net
>> (Jim Menegay) wrote:
>> 
>> >r norman  wrote in message
news:...
>> >> On Thu, 15 Apr 2004 03:57:36 +0000 (UTC), sharikoff{at}lycos.ru
>> >> (chupacabra) wrote:
>> >> >The question that perplexes me - why does evolution
progress from the
>> >> >simple to the complex? 
>
>> >> The general idea now is that there is no
"progression" of evolution
>> >> towards more and more complex forms.  
>> >> Another way to look at it is as a random walk process.  Evolution
>> >> tends to spread out organisms in all directions. 
However, it started
>> >> with simple things and there is a lower bound to how simple an
>> >> organism can be and still be alive.  So there is necessarily an
>> >> increase in average complexity with time. Still, most things remain
>> >> simple.
>
>> >A vivid way of making this same point is to ask for an explanation
>> >of the "remarkable" southward vector of human
migration in the first
>> >few millenia after the Berring land bridge was crossed.  What
conceivable
>> >force drew these early emigrants enexorably to Tierra del Fuego?
>
>> I like it!  A very nice example.
>
>Thank you.  But I must tell you that my example was only intended to
>illustrate my understanding of your idea, not my endorsement.  In fact,
>I believe that your idea, which I will refer to as the "diffusion
>theory", is either incoherent, unhelpful, unscientific, or contradicted
>by the evidence.
>
>The theory would be incoherent if it were expressed, as it sometimes is,
>in the form: "It is impossible to define 'complexity', and even if you
>could define it, we already understand it".  We will therefore assume 
>that your version of the theory is not incoherent - that you accept that
>complexity may be definable, though consensus has not yet been achieved
>on the exact definition.
>
>The theory would be unhelpful if it were used to discourage investigation
>into the best definition of 'complexity' and the collection of empirical
>evidence.  We will assume that you do not wish to be unhelpful.
>
>In fact, I will assume that you agree that one useful metric for 
>complexity is the information content of the genome - that is, the
>size of the genome adjusted downward to account for those sites where
>drift is unconstrained.  This is roughly Kolmogoroff complexity, I think.
>
>The theory is unscientific if it is maintainable regardless of what the
>empirical evidence actually shows.  I don't particularly relish using
>the P-word, but a scientific theory has to make predictions that can
>conceivably be refuted by the evidence.  I wonder whether you would
>agree with me that the diffusion theory makes the following specific
>predictions:
>
>1. The rate of max complexity increase decreases with geological time.
>This is because it is a characteristic of a random-walk mechanism that
>the square of the max complexity measure would be expected to grow only
>linearly.
>2. Looking at a single species, it is just as likely to take a step
>toward lower complexity as toward higher complexity.
>3. Out of all possible organisms that might be viable in a particular
>ecological niche, it is the least complex one that is likely to sieze
>the niche first.
>4. When an appropriate weighting scheme is used that gives appropriate
>weight to the bacteria and other simple organisms, it is seen that 
>average complexity is not very high (obviously), and it is not really
>increasing.  The typical modern bacteria is not more complex than its
>ancestor of 2Gy ago.  The typical modern protozoa is not more complex
>than its ancestor of 1Gy ago.  Or, if you focus on a particular species
>and niche, the modern cyanobacterium is not more complex than its 
>ancestors.
>
>The theory appears to me to be not borne out by the facts. 
>1. The leading edge taxa in the rise of complexity - the metazoa and
>the metaphytes - appear to have increased their complexity more within
>the last 250My than in the 250My before, and much more than in the 
>500My before that.  Complexity increase among the already complex seems 
>to be accelerating.
>2. There appears to be a kind of Cope's law of complexity - complexity
>tends to increase in almost all branches of a taxon.
>3. It seems clear to me that while natural selection may be an economic
>optimizer, it is not an optimizer of organizational structure.  Successful
>organisms are much more complex than they absolutely need to be.
>4. You seem to believe that the simplest organisms have not increased 
>much in complexity over the past 1-2Gy.  I suspect that they may have
>doubled in complexity.  Our conflicting intuitions may be testable using
>comparative genomics - though at the present time we don't have enough
>"branchiness" in our phylogenetic trees to reliably reconstruct models
>of the ancestors of modern microorganisms.  The phenomenon of lateral
>gene transfer also creates problems.  So, this disagreement may remain
>unresolved for a long time.
>
>For all of these reasons, I think that the phenomenon of the increase
>in complexity is a real one which deserves an explanation.  However,
>I definitely do not believe, as some people seem to, that the explanation
>is to be found in the mathematics of "complex system dynamics" and 
>will be revealed to us in the next book by Prigogine, Kauffman, Wolfram, 
>or Chaisson.
>
>I think we already have an adequate biological understanding of why
>neoDarwinist evolution leads to increased complexity over time.  We
>know that increased complexity arises because "duplication and divergence
>of function" is the mechanism that is available.  This mechanism is
>used at both the level of the genes and at the level of morphogenesis.
>By contrast, there is no simple way for a working organism to shift
>to a lower complexity.  To use the terminology of business administration,
>NS is just not very good at "re-engineering" the organism to,
for example,
>find commonality between two functions and reorganize/simplify the way
>that functionality is delivered.  
>
>So, how does my idea stand up against my criteria of coherence, usefulness,
>refutability, and correspondence with the facts?  Well, I hope it isn't
>incoherent, but I must admit that it has a "shut down the
debate" attitude
>that is unhelpful.  I will leave it to more expert critics to evaluate
>it regarding refutation and verification.

I don't want to ignore you but I do have approximately 60 exams to
finish grading and return tomorrow and another 70 for Wednesday.  Your
post demands some actual thought and consideration (unlike most of
what gets posted on news groups).  I'll try to get to it as soon as I
can.
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