From: onar@hsr.no (Onar Aam)
Subject: Re: Microevolution and Macroevolution
Organization: Rogaland University Centre
Date: Mon, 12 Oct 1992 08:17:08 GMT

>>microevolution is the change which occurs within a specie. In short, diversity.
>>macroevolution is the change which "transforms" a specie into another. In short,
>>INCREASE in complexity.
>


>(Assuming the above distorted definitions to be valid):

Science change, you know. So do defenitions, and I seem to be more up to date
than you.

>Do you propose that there is a different genetic mechanism underlying
>macro and microevolution? If yes, what? If no, how do you draw the
>line between micro and macro?
>

Yes, I do propose that there is a different mechanism underlying micro- and
macroevolution.

Microevolution are due to random changes (mutations)in the DNA-sequences. These 
changes may cause new traits to occur. The problem, however, is that this is a 
limited way of change. Ex: No matter how many random changes that occur in a 
bacteria, the offsprings will not diverge severely from the 'original' bacteria. 
(I.e. a random change,yes, even a billion random changes will not make a bacteria
into a dog.) In technical terms we might say that an organism (with N genes) is a
DYNAMICAL SYSTEM which means that the organism can successfully change BUT within
certain bondages. In other words, LIMITED change, or change within the DYNAMIC
RANGE of the system. (provided that the # of genes is constant)



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.

That the dynamic system is unstable means that new traits may have occured but
aren't fully adapted. I mean, imagine the first bird that flew. Couldn't have been
a pretty sight...
 

>Why does speciation have to involve an 'increase in complexity'?
 

Because of the defenition 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.


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.

>Convince us with concrete mechanistic explanations why these are
>separate topics.
>
>>What creationists also has pointed out: Evolutionary change, more often than not,
>> occurs suddenly and in steps. Which is absolutely true. 
>
>They've manipulated the meaning of the terms to suit their interests by
> describing an alleged barrier on variation that prevents speciation;
>what this barrier is, they won't explain. 
>cheers mike
>

These last questions have answered themselves based on my previous reasoning.




Onar.
Newsgroups: talk.origins