On Friday, February 02, 2001 7:47 PM John Marlow johnmarlow@gmx.net wrote:
Marlow quoting Hogan:
> Hmm. Difficult to know which to pick. Maybe the question of the
> origin of the stupendous amount of information in a genome -- genetic
> program coding not only structural organization & growth, but
> instincts, behavior, responses to injury, stress, etc. etc.
How is this being measured? I've cited the work of Brooks and Wiley in
previous posts. They use a formalism to evaluate the information in living
systems.
However, the surprising thing should not be the amount of information, but
the amount of noise in living systems. I'm sure we are all aware of DNA
changes -- to stick with DNA; the focus should not be on DNA alone -- many
random changes in DNA have no or little impact on anything else. Part of
this is because DNA and proteins made from it -- indirectly, of course --
have active sites and passive sites. Most of DNA and most of protein is
passive -- just there for the ride and as long as it doesn't affect anything
else, it doesn't make a difference. An analogy might prove helpful here. A
protein's active site might be compared to the tires on a car or any other
vital component. The license plate cover on a car, however, is more like a
passive site. It has no or little effect on performance. It might on
margin, but, for the most part, it does not.
(Now, imagine if lots of random change accumulates in passive areas, then an
active area changes or an area changes that makes formerly passive areas
active. You might wind up with a huge shift in DNA or protein behavior.)
> If
> Darwinism were correct, such programs accumulated from nothing in
> tiny increments. Hence every evolutionary step along the way, on
> average, should add information to the growing genome. But _not one_
> of the examples usually cited in textbooks etc. as "evolution in
> action" has ever been found to add information, and so cannot count
> as a meaningful evolutionary step. Bacterial resistance to
> antibiotics, for example, (e.g. streptomycin) results from a
> deterioration that loses the molecular specificity necessary to
> accept the antibiotic's deactivating "key" -- i.e. a loss of genetic
> information, not a gain. The much-touted pepper moth in England is a
> simple instance of population dynamics, the dominant color changing
> as the environment changes. But light and dark varieties were both
> present to begin with. Nothing genetically new came into existence.
I agree with the peppermoth example. In fact, Brooks and Wiley use it in
their _Evolution as Entropy_ to highlight the difference between reversible
and irreversible change. They believe the latter is more important to
evolution. However, you seem to be overlooking the fact that variations can
arise. We'd have to do further, deeper analysis to see why both varieties
exist -- under the assumption that such variation is not primary.
> Yet these are offered as among the best examples. Programs of this
> complexity don't write themselves from random changes. In
> fact, the reverse -- the more complex and precise a program becomes,
> the more random changes are likely to disrupt it.
Genomes, in general, are very resilient to some disruptions. Even though,
e.g., humans get cancer, even most cancer victims live long enough to
reproduce, raise their children, and so on. I would look at the problem the
other way. Why is there so little information in any genome of any
relevance to the organism?
> It's important to distinguish between information and the medium
> holding it. "Macbeth" remains the same play whether represented as
> ink on paper, dots on a diskette, sound waves, laser pulses, etc.
> Similarly with genetic information. I'd contend that saying genomes
> are just an emergent property of DNA is like saying Macbeth is an
> emergent property of ink and paper, missing the whole point that the
> medium isn't the origin of the message. It just carries it.
Such a distinction makes sense in an abstract symbol system like writing.
The alphabet we use has no necessary relation to information coded in it.
"Macbeth" would still be "Macbeth" even if it were coded in, say, Unifon --
and we knew how to read Unifon. However, the relation between DNA and an
organism is a lot different. The genome of any living thing is not an
abstract symbol system. In fact, it's an active information system and
makes proteins and regulates itself. There are triggers of when to do
certain things and what to do in it. It requires no outside interpreter and
it does have emergent properties.
Of course, the analogy between "Macbeth" and biological information breaks
down on these points. (But getting back to random mutations, imagine
changing a period to a comma in "Macbeth." How much meaning would be lost?)
As for not wanting to debate the issues, well, whatever.:)
Cheers!
Daniel Ust
http://uweb.superlink.net/neptune/
Film recommendation: "The Color of Paradise."
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