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From: usenet@nlm.nih.gov (usenet news poster)
Newsgroups: comp.ai.neural-nets
Subject: Re: Observations on the State of NN theory
Message-ID: <1990Aug23.143902.758@nlm.nih.gov>
Date: 23 Aug 90 14:39:02 GMT
References: <schraudo.651012988@beowulf> <3430010@hpwrce.HP.COM>
Reply-To: states@tech.NLM.NIH.GOV (David States)
Organization: National Library of Medicine, Bethesda, Md.
Lines: 49

kingsley@hpwrce.HP.COM (Kingsley Morse "km>") writes:
states@tech.NLM.NIH.GOV (David States "ds>")
ds> I am not aware of any evidence for genetic type algorithms actually
ds> playing a role in biological learning. 

km> My understanding is that twin studies have shown that intelligence is
km> inherited. (Twin studies measure twins who were separated at birth, to 
km> distinguish between inherited and environmental effects.) I'm assuming that
km> if intelligence is inherited, then it's encoded in chromosomes, and thus
km> operated on by GAs. 

The issue of genetics and IQ is contentious to say the least.  First,
you should be aware that the "classic" twin studies by Cyril Burt are
now known to have been totally fabricated and are a classic example of
scientific fraud.

Leaving the specifics of IQ and twins aside, genetics determines the
underlying structure of an organism (you are not a kangaroo because
your development was not governed by a kangaroo's genes).  Intelligence, 
to me, refers to adaptability and learning ability.  The fact that you
sneeze when your nose is tickled may be genetically determined, but it
is not particularly evidence of learning.  In the sense that humans are
generally regarded as being more intelligent than kangaroos, I suppose
that genetics has a role in intelligence.

ds> Specifically, somatic cells, such as neurons, do not undergo recombination.  
km> Can you be more specific? Do you mean that the components of individual 
km> cells don't undergo recombination? Do you mean that entire cells aren't 
km> recombined with other cells? What references are you using?

Biological neural systems are composed of "somatic" cells like the most of
the rest of the body.  This means that these cells have lost the ability
to undergo sexual recombination with exchange of genetic information (meiosis)
and instead can only undergo asexual division (mitosis).  In the adult brain,
neurons have generally lost the ability to divide completely.  Therefore, 
during the training of a biological neural system, individual neurons have 
no way of recombining genetic information.

See:
	Watson et al, Molecular Biology of the Gene
	Darnel, Molecular Cell Biology

km> And by the by, what was that "x" in your computational complexity table 
km> under the "Really Smart Systems" notestring?

Just an arbitrary empirically determined number so C = x^N implies that C
grows exponentially with N without saying exactly how fast.

David States