From: D. F. Siemens, Jr. (dfsiemensjr@juno.com)
Date: Sat Nov 01 2003 - 13:55:06 EST
On Fri, 31 Oct 2003 20:51:21 -0500 Walter Hicks
<wallyshoes@mindspring.com> writes:
>
>
> bivalve wrote:
> <snip>
> > Engineering is looking for optimization, and thus resorts to a
> strategy similar to that promoted by Intelligent Design advocates.
> Evolution only requires good enough; rigorous selective pressure
> would be necessary to approach optimization, and even then it is
> contingent on historical possibilities and other constraints.
> E..g., humans might find a third grasping appendage handy, but tails
> were lost in the ape/human lineage (and were not prehensile in that
> group anyway). This historical constraint limits human evolution,
> but an engineer could simply graft something on. Raising the
> mutation rate in the hopes of growing another appendage would
> probably be more detrimental due to harmful mutations than effective
> towards the goal, and so other constraints come into play.
>
> Yes, but as I said, the basic point is to imitate nature because
> nature has been so effective in getting :the "best": solutions to a
> given parameter (not just a useful one ----- and this is indeed the
> case. That is why DARPA clings to the approach. If the evolutionary
> model were correct, then GA should indeed get the best answer for
> parameter X, just as nature does. When radar was invented, we found
> out that bats were way ahead of us. I believe that they still are.
> We cannot make devices that smell as well as a dog can, etc. If the
> biological model were correct, then GA would produce far more than
> the rough answer that it currently produces.
>
> <snip>
> Walt
>
I'm trying to figure where you got the idea that nature via evolution
either produces optimum solutions, or the theory is erroneous. Survival
does not direct change, but only sorts out what is available within the
restrictions of the specific environment--with lots of room for chance
events that have nothing to do with fitness. A different environment
would probably show a different combination to be most fit. Further, the
environment is variable to a greater or lesser extent. There is no way to
maximize the variety of genotypes for testing in natural circumstances,
and the test at best is of phenotypes. All this is very different from
the human use of GA, which generates a maximum number of variants in a
protected environment and tests for desired results. As I understand the
situation, if we totally understood all the factors involved, we could
design and construct an enzyme, say, that would do the required job most
efficiently. But this would be worse than solving a random walk problem,
for the specific goals within the problem are not set. Lacking
understanding, we throw everything we can at the problem and sort out
results--a shotgun approach.
To bring down a flying duck with minimum expenditure of energy, a .22
short through the head is probably the best. The .177 air rifle pellet
does not have the power to fly far enough and hit hard enough. However,
duck hunting with a .22 is futile, for no one can aim accurately enough.
Even assuming that the trajectory could be calculated exactly and the
muzzle pointed to microseconds, variations in the charge and its burning,
and in the bullet, plus whatever other variables might enter in, would
make hunting ducks with a .22 stupid. A shotgun load covers a large
enough area for the hunter to have a reasonable chance of downing a duck,
with a much larger expenditure of energy and no guarantees. None of this
demonstrates that rifles are non-functional.
Dave
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