"dkomo"  wrote in message
news:ce36sv$13iu$1{at}darwin.ediacara.org...
> Richard Dawkins mentioned an idea to characterize complexity in his
> recent book _A Devil's Chaplain_.  Dawkins has way of coming up with
> simple ideas which are often quite powerful.  Here's what he wrote:
>
> "We have an intuitive sense that a lobster, say, is more complex (more
> 'advanced', some might even say more 'highly evolved') than another
> animal, perhaps a millipede.  Can we measure something in order to
> confirm or deny our intuition?  Without literally turning it into
> bits, we can make an approximate estimation of the information
> contents of the two bodies as follows.  Imagine writing a book
> describing the lobster.  Now write another book describing the
> millipede down to the same level of detail.  Divide the word-count in
> one book by the word-count in the other, and you have an approximate
> estimate of the relative information content of lobster and
> millipede.  It is important to specify that both books describe their
> respective animals 'down to the same level of detail'.  Obviously, if
> we describe the millipede down to cellular detail, but stick to gross
> anatomical features in the case of the lobster, the millipede would
> come out ahead."
>
>     --Richard Dawkins, _A Devil's Chaplain_, p. 100
>
> He then presents a plausibility argument as to why the lobster's book
> would be longer.  The millipede's segments are all the same.  So its
> book would have one chapter describing the segment, followed by the
> phrase 'repeat N times.'  The lobster's segments, on the other hand,
> are all different, so it needs separate chapters for all its segments.
>
> Note that Dawkins is equating information content with complexity
> here, and supplying a workable, but partially qualitative definition
> of both.

I think that Dawkins is talking about Kolmogorov complexity here.  To
my mind, the key point about Kolmogorov complexity is that it insists
that the language used to describe the object must be rich enough to
say things like "repeat N times" and more complicated variations of that
phrase.  It doesn't limit us to a fixed set of phrases.  (But, in thus
unleashing descriptive power, it makes itself somewhat ambiguous and
very non-operational as a metric.)

> I make the following observations.  Mammals would come out more
> complex than "lower" forms of life because describing their
> neurologies, intelligence and social behaviors would fill volumes.
> Describing human psychology and culture in detail would fill entire
> sets of encyclopedias.
>
> I'm undecided about how to handle social insects like bees, termites
> and ants.  Individually these creatures are no more complex than other
> insects.  But their interactions produce incredibly complicated group
> behavior and structure -- an example of the phenomenon of emergence.
> There's very little neurology involved.  It's just large numbers of
> simple agents following simple rules producing very complex emergent
> behavior.  Do you put just the rules of the individual insect
> interactions into their "book" or do you describe in full how the
> entire colony functions?  The size of the two books will differ
> considerably.

There are three different kinds of complexity being confused here.
Or perhaps I should say that you are using your complexity metric to
measure the complexity of three different kinds of objects.
These three are:
* Organism complexity as specified by genetics.
* Organism complexity after development and learning.
* Societal complexity - ie. complexity of multi-organism composites.

It should be obvious that societal complexity is the complexity of
a different kind of thing from organism complexity - hence those
encyclopedia volumes about human culture just don't count in
assessing whether a man is more complex than a mouse.  They count
only when assessing whether human culture is more complex than mouse
culture.

To understand the difference between my first two kinds of objects,
make the assumption that the essential genetic difference between man
and mouse is that in the genetic specification of the pre-frontal cortex
the mouse specification says "repeat N times" whereas the man
specification says "repeat 2N times".  That is not much difference
between man and mouse in complexity at the genetic level.  Also assume
that the genetics does not preprogram the connectivity of those pre-frontal
neurons - that the connectivity gets established in the course of
development by learning.  Writing a description of what that interconnect
ends up being is going to take a lot of information, for either man or
mouse.  But it will take at least twice as much for the man, because there
are twice as many learned connections to describe.  Perhaps some of those
additional connections serve to encode language.  The mouse just doesn't
have room for language.  Hence, the Dawkins/Kolmogoroff iterator "repeat
N times" doesn't necessarily add much complexity at the genetic level,
but it enables considerable complexity at the developmental/learning level.
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