X-Message-Number: 3488
Date: 14 Dec 94 03:27:29 EST
From: Mike Darwin <>
Subject: SCI.CRYONICS genetics and neural connections

There has been some speculation and commentary by Cotzee and Donaldson about to
what extent neural connectivity is specified in the genome of  higher animals
(mammals).  While to my knowledge the EXACT experiment Thomas proposes (
sectioning brains of twins and comparing the overall connectivity) has not yet
been done,  there is a very significant body of related evidence which IS
established as fact. 

 I have known about this for a long time (since early childhood) since my Dad
was a police officer specializing in indentification and crime scene forensics.
He spent many, many hours of his professional life in front of huge rotating
racks (Diebold machines) containing tens of thousands of finger,print cards
trying to make a "match" between a known, classified print on file, and the
"suspect's" or the suspicious print found at the crime scene.

Being a curious lad I had him teach me basic fingerprinting techniques and a
very little about the classification system.  One of his first lessons was to
show me the prints of identical twins (who also tend to follow each into lives
of crime!).  The interesting thing here is that while there ARE broad
similarities, the prints are not identical and even an inexperienced child can
tell them apart.  Thus the classic statement "no two people have exactly the
same fingerprints" is true even of twins (even if in the vast statistical
universe of all the human beings who ever have or ever will live this statement
may not hold up).

Furthermore, I once dated an opthamologist who had the opportunity to make
routine retinal photographs of his patients (this is done routinely by good
opthamologists to establish a "normal" baseline).  He also remarked that twins
to *do not* share "retinal prints" (i.e., blood vessel patterns.

Finally, there is less rigorous evidence (since we don't know the causes of
theses behaviors) in the form of identical twins who:

a) are not both heterosexual or homosexual (although the likihood that both will
share sexual orientation is, if I am not remembering incorrectly, about 80%,
even for twins reared apart from birth).

b) surgeons tell me that it is not uncommon to see different anatomy such nerve
or vessel positions between twins.

c) Some twins seem gifted with "special capabilities" that the other does not

share.  For instance I once knew two gay identical twins one of whom was musical

and made his living performing and working with music, and the other of whom was
nearly tone deaf. Of course such a striking difference in ability could be due

to damage during or before birth to one twin and not the other.  However, of the
many twins I've talked to, the majority report differences in abilities as well
as many similarities.

The point here is that DNA is NOT, I reapeat, NOT a blueprint.  It is a recipie.
For instance, if you bake a chocolate cake you can get quite consistent results

if you scrupuously reproduce the baking/preparation conditions; the cake will be

moist, even, full flavored, etc.  But what you DO NOT get is every gas bubble in
the smae place in each cake, or every inclusion or variation in density in the
same spot.  Ditto with twins.

Finally, I've done a little work with "genetically identical rodents".
Anatomical variations occur such as a differences in location of blood vessels
and pattern of vessels (I've noticed this in the mesentery of such animals.

Sooooo, I would hazard that the neural connections of twins ARE NOT encoded
precisely in the geome.  In fact, I think an indirect proof of this might be
made by someone (who unlike me) is not a mathematical cripple) by calculating
the number of bits (and consequent volume of DNA) that would be required to
encose all the trillions of connections......

Mike Darwin

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3488