From: lamoran@gpu.utcs.utoronto.ca (L.A. Moran)
Subject: Microevolution and Macroevolution
Organization: UTCS Public Access
Date: Tue, 13 Oct 1992 03:38:40 GMT


Onar Aam writes is trying to come up with a theory that distinguishes 
between micro- and macroevolution. He says,

     "How then CAN a bacteria change into something else? (All living
      organisms on earth evolved from bacterias so they obviously have 
      the ability) This is where we turn to macroevolution. Since organisms
      are dynamical systems with a limited dynamic range we have to ALTER
      the bondages of the system. And, as any genetician can verify, these
      bondages can not be altered with random changes in the DNA-sequences.
      The only way to alter these bondages is to alter the number of
      genes. And because of the second law of thermodynamics this change
      must be positive (increase in number of genes). A removal of a gene 
      is lethal. (Obs! there might be local exceptions). When increasing
      the number of genes there is a possibility that the genetic system 
      becomes unstable. This, in terms, means that the bondages of the 
      system can change. This, and only this, is the major cause of 
      speciation. As you might understand genes doesn't grow gradually, 
      they pop up suddenly (through gene duplication). This is the technical
      explanation to Punctuated Equilibria (read the FAQ). The dynamical
      systems change suddenly, and thus, species change suddenly and 
      rapidly."

I usually consider such postings to be a form of light entertainment but 
just in case anyone is confused by such ramblings let me point out that
all living organisms are NOT evolved from modern bacteria. It's true that
we all share a common ancestor that looked more like a bacterium than a
monkey but that does not mean that modern bacteria have the ability to 
change into a monkey. Modern bacteria are highly evolved and specialized
organisms that are as far removed from our common ancestor as you and I.

It is not true that speciation is associated with a change in the number of
genes. There are thousands and thousands of species of bacteria, for example,
and they all appear to have about two thousand genes. Furthermore, it is very
unlikely that different mammals have significantly different numbers of genes
or that their common ancestor had fewer genes.

Onar was asked why speciation has to involve an increase in "complexity"
and he replied,

     "Because of the definition of complexity. Complexity is simply 
      the amount of information in the ACTIVE and distinct genes of an
      organism. And since severe change in a specie can only occur by 
      increasing the number of genes it is obvious that speciation have 
      to involve 'increase in complexity'.

      There are various examples of this. The best one I can think is 
      the evolution of the whales. Land animals evolved from fish. They 
      lost the original traits of a fish. Whales went 'back' so they had
      to evolve the same traits that their ancestors had lost. This 
      happened through increase in the number of genes."

This fanciful explanation doesn't deserve much comment but just for the record
I'm not aware of any evidence that species of whales have more genes than
other mammals. In fact, I'm not aware of any evidence that whales or other
mammals have more genes than fish or other vertebrates. 

Let's assume, for fun, that Onar is correct. Beginning with an ancestral
vertebrate several hundred million years ago we now see three groups of
organisms that are the product of many speciation events; fish, whales,
and other mammals. Now, since all of these lines saw an increase in the
number of genes (recall that we are assuming that speciation is associated
with an increase in genes!), how can we predict which group will have the
most genes? Let's assume that the thousands of species of modern fish that 
have evolved since the time of the common ancestor end up with more genes 
than the various species of mammals (because there are more species of fish
than there are of mammals). If whales "revert" to the ancestral state won't 
they have fewer genes than modern fish?

Onar goes on to say,

     "Another point is that life on earth is tending toward greater 
      featuristic complexity (not just greater genetic complexity). 
      Oh never mind. That is to large a topic to explain."

Onar, please don't leave us in suspense. We'd love to know how you measure
"featuristic complexity" especially among those groups that are in the midst
of rapid radiations such as arthropods, flowering plants, molluscs, and 
several catagories of bacteria.

Laurence A. Moran (Larry)
Newsgroups: talk.origins