"Kevin K." <KK at _._> wrote:
> The situation is even worse with more primitive organisms. If the brain
> is such an incredibly complex (indeed, unsimulatable) computing device,
> then why is it wasted on dumb finite-automata style tasks like opening a
> gill flap? It may not be possible to exactly simulate the brain of a
> rabbit with a digital computer (just as it is impossible to exactly
> simulate the behavior or any real system), but it is very easy to
> simulate the *behavior* of a rabbit with a digital computer. Rabbits
> have an extremely limited repertoire (running, standing, digging,
> grooming, mating, eating, fleeing, fighting etc.) which they repeat over
> and over. So where is all the brain power going? According to your view,
> these animals are endowed with an infinite state computer, so why can't
> it outperform (say) a 486 with an 8MB hard disk? Why don't we use rabbit
> brains as archival storage devices?
I would like to see this simulated behavior of a rabbit. The rabbits
behavioral "repertoire" might be limited, but it is capable of performing
them in direct response to changing environmental conditions (internal and
external). It does not merely repeat the same tasks over and over again.
The issue is not one of "power", but of complexity.
For what it's worth, here's my take on it:
Living organisms seem to be optimized for handling partially recursive
functions, even non-computable ones. DNA itself is capable of handling any
recursive function, including non-computable ones. Unlike DNA, however,
living organisms seem also capable of approximating state-based information.
Still, the ability to handle finite-states seems extremely limited in living
organisms.
RAM machines, on the other hand, are specifically designed to handle
state-based information. As such they excel in performing tasks such as
"archival storage". However, they are poorly suited for handling partially
recursive functions. If I understand correctly, most functions in RAM
machines compute in exponential time, which makes them inefficient at
modeling natural systems.
Just as we strive to make RAM machines better able to imitate natural
systems by increasing the amount of resources available to it and by
developing more efficient algorithms; evolution seems to have resulted in
the development of DNA machines better able to approximate state information
through increased resources and more efficient algorithms.
I see no logical basis from which to compare performance of RAM machines and
DNA machines. RAM machines may be more ideally suited for modeling certain
behaviors; DNA machines may be more ideally suited for modeling others.
