Adam Crowl wrote:
>
> Hi ASA
>
> Information in DNA and its relationship to an organism is an interesting
> issue with some deep implications for our understanding of evolution.
*********
change "evolution" to "organisms"
Stop reading conclusions into your basic statments.
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Here's
> my rough outline of why we may be so confused about it...
>
> Massie wrote
>
> >Really, can you count the bytes of information in
> >the eye
> >for example and then estimate the number of bytes of information that
> >could
> >be generated per generation and then the number of generations.
> >Something
> >to hang this on, just something.
>
> To go from bytes in the eye, or in the brain [another example of organismic
> complexity] there is no easy relationship between DNA and cellular
> organisation. The human eye contains some 100 million receptors and a layer
> of preprocessing edge-detecting systems which send organised information to
> the visual cortex.
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And the biochemistry is incredibly complicated.
*********
>
> The human genome only contains some 300 - 90 million base-pairs that
> actually code for proteins - the rest is tied up in repeating segments,
> non-functional pseudo-genes and marker. timers and non-protein coding stuff
> that is useful. Yet the human body has over a thousand trillion cells with
> 256 types of cells. How does such a small amount of infomation translate
> into the incredible complexity of eyes, brains, nerves, muscles and so
> forth? The underspecification is a factor of more than a million, perhaps
> even a billion or more considering the amount of specification a single
> cells type and place would require. What's true for humans is true for
> almost all animals - underspecified by BIG factors... I think round worms
> [nematodes] are the most complex FULLY specified animals.
***********
Incredible how prolific "chance" is at creating complex things. What
side are you arguing for?
**********
>
> The miracle
*****
Good choice of words.
**********
of the How is, I suspect, analogous to how a few lines of code
> can produce the immense complexity of fractal images... ALGORITHMIC
> COMPRESSION. And the cells are self-replicating "nano-computers" that bring
> it about by running the "body program" that they all share. The input is the
> time and generation number of the cells and the extra-cellular environment,
> filled with hormones, signalling molecules and other cells. I suspect that
> electromagnetic fields are also involved but that's unproven.
>
> So imagine trillions of little computing machines putting a living thing
> together out of their collective actions. Kind of like the pixels in an
> image of a complex fractal - simple global and local rules governing what
> state it will be in. Or the complexity that can be created by cellular
> automata [an aptly named analogy] using the same rules for every cell and
> yet mimicking living things. However no CA has ever unfolded from "simple"
> beginnings like cells proper. But the idea of complexity out of simplicity
> is there.
>
> That's why there is no easy route from genetic mutation to a full blown
> organism.
**********
And why I am asking for some kind of "existence proof."
*******
One base change can produce dwarfism in humans - a simple change
> affecting trillions of cells. Yet a full chromosome duplicated in some
> people produces Downs Syndrome which is not the horrific disaster that so
> much random change might suggest, since it is often quite mild in outcome.
> And dwarfism is not a horrific mutation either, so don't get me wrong - many
> see it as a normal variation.
>
> Mutations can affect single proteins or whole developmental sequences and so
> their effects vary widely. Most are just plain neutral, many are harmful and
> a few just make people subtly different. That's where the variations we call
> "alleles" come from. A very few produce a difference that might mean life
> or death and so natural selection comes into play... subtle or unsubtle.
> Subtle selection takes a few generations to be significant, unsubtle usually
> kills in childhood or child-bearing years.
>
> Since currently we know so little about development - though more all the
> time - there's a lot that can't be answered about how organisms went from
> one form to another. But the fact remains that seemingly related organisms
> exist and others that neatly bridge the differences between groups keep
> getting dug up as fossils... so something is definitely going on that is
> suspiciously like Darwin's "descent with modification".
**********
Decent with modification is not the issue. The concept of evolution
arrises naturally when the fossil sequence is examined and the time
sequence of animals relized. But, as they say "the devil is in the
details." Even the evolutionary magazine Scientific American once ran
an article pointedly poking at evolutionary theorists to integrate the
reality of the Cambrian explosion into the theory.
>
> Adam
>
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