Re: underwater space aliens

H. M. Hubey (hubey@pegasus.montclair.edu)
21 Oct 1995 22:53:08 -0400

Alex Duncan <aduncan@mail.utexas.edu> writes:

>>This third category is produced because we cannot tell simply
>>by looking (or any other way, at least these days) if the
>>change was adaptive (positive) or maladaptive(negative). But
>>regardless of whether we know which it is, it is one of them
>>almost all the time.

>Please tell us, oh wise one (who thinks horses' knees bend backwards) how
>you know this. Been reading some biology texts lately? Seems pretty
>unlikely, as you still show no signs of knowing shit from shinola.

WEll, it looks like another guy who needs to be taught a few
lessons on how to behave and also on how little he knows
about anything in life.

Where do we start. Negative feedback! Where does it come from?

I already told you but here's a simple version. TAke a linear
DE with constant coefficients and take an integral transform.
Solve for the output (algebraically). Draw the usual box
diagram with the BB with input and output. At the beginning
where the output feeds back into the inputs there's a summer.
And it is here that it's easy to see where the terminology
comes from. In any case, Here's a simple example

If T > S THEN
Decrease T {i.e. turn on AC}
ELSE If T < S THEN
Increase T {i.e. turn on Heat}

IT could be the temperature controller in a building. it could
be the thermal regulator of your body. To decrease T you'd
sweat; to increase T you'd tremble.

The only part where nothing happens is if T=S. One could also
write DE's to describe this kind of stuff and in fact, the
terminology comes from there. And here are two theorems
from control theory. In order for a system to be controllable:

Positive feedback is neither necessary nor sufficient.
Negative feedback is both necessary and sufficient.

IF you think if equations describing evolution every change
has to affect the evolutionary trajectory one way or the other;
either positively or negatively. If not so, then evolution
equations certainly have strange behavior. Come to think of it
I can't imagine writing any dynamic equations in which changes
would have no effect on the path.

Why don't you show me how it's done if it can be done at all.

Perhaps what you want to say is that evolution is not a science
and hence none of the mathematics which has been so unreasonably
effective for all science cannot be used in your field.

I've heard these comments before but never from scientists,
maybe romantics or literature majors but never scientists.

There
>are many features of all organisms that can vary without having any
>effect whatsoever on the adaptive fitness of the organism. (This has been
>tested.)

I already explained this to you once. You cannot know because you'd
have to wait forever in order to be able to know that. Remember
this thing called "falsifiability". Confirmation and verification
has already been given up by scientists and philosophers of
science. WE went through this only a couple of weeks ago.

>Well, no it isn't. I repeat, the idea that features can vary without any
>adaptive effect on the organism HAS BEEN TESTED AND FOUND TO BE TRUE.

people who've done so should be ashamed. I'll accept it as
an approximation like in all sciences.

And I repeat, it cannot be done.

-- 





				Regards, Mark

				http://www.smns.montclair.edu/~hubey