🚀 go-pugleaf

In article <103684@netnews.upenn.edu> ,
rowe@pender.ee.upenn.edu (Mickey Rowe) writes:

>So where are you headed with this? 

A few weeks ago I made a wild statement in another news group
(comp.ai.philosophy) that the brain might well be the dumbest organ in the
body.

This idea was based on the concept that cells-as-computers can be seen as
more than an analogy or metaphor, that cells actually perform in ways that
are very similar to other digitally controlled systems, under the direction
of DNA.  

The brain statement is based on the fact that neurons have less DNA per
unit weight than other kinds of cells (eggs-cluding eggs and who knows what
other special cases).  Neurons which survive just keep growing and
branching, adding an additional burden on the existing nucleus.  

If cellular smarts is important to the survival of the organism, then one
kind of brain smarts diminishes with age.  Of course the synaptic
organization type of smarts continues to develop with age, up to a point,
and I'm sure it adds more survivability to the organism than is lost in DNA
power.

Anyway, the dumb brain statement was meant as a joke, but in the process of
defending the argument I developed the need to know a few molecular
biological basics such as the rate at which the nucleus issues instructions
to the cellular machinery.

If we take Sean Eddy's estimate of the mRNA data rate of 200 kilobytes per
second per cell (article <eddy.725706161@beagle>), and if we figure one
codon triplet equals one computer type instruction, then I get 3 x 10^5
instructions per second per cell.  With the human body's cell count at
10^14 (plus or minus), that comes to about 3 x 10^19 cellular instructions
per second.  

At 100 billion neurons per human nervous system, the cellular computing
power would be about 3 x 10^16 or about .1% of the body's total cellular
computing power.  Not terribly impressive since the nervous system probably
accounts for about 2% of the body weight (That's using the familiar 3 lb
quote in the popular literature, I don't know what percentage is glial
cells).

By comparison, Hans Moravec estimates brain (synaptic) power at 1 x 10^13
computations per second, but of course that's apples and oranges.

Anyway, thanks to everyone who responded.

--
Ken Easlon                | "...somebody spoke and I went into a dream..."
ken@holonet.net           |    -Paul McCartney
Pleasantly Unaffiliated   |