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. 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.
>
> 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.
>
> The miracle
*********
A great 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"
*************
Programs are instruction sets to be run by computers.
Where did the instruction set come from?
Where did the computer come from?
Where did the mechanism to power the computer come from?
Computers have to disapate heat, where did the radiator come from?
How did the initial computer get started?
What side are you on anyway? It seems like you are aguing for
irriducible complexity.
*****************
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.
***********************
Perhaps there is no route to a full blown organism through genetic
mutation.
*******************
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
*******************
Actually you know so little about development that you cannot posit an
existence
proof for development through genetic mutation.
**************
- 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".
*************
Granted that there is a sequence of organisms and granted that Darwin's
hypothesis
was a good hypothesis. But since then there has been the discovery of
genetics and
biochemistry and there is no recognition in your post about the
complexity of
mutating to the complext biochemical processes which you lecture are
incredibly
unspecified (actually I think you mean specified by means unknown).
Bert M
This archive was generated by hypermail 2b29 : Mon Jan 31 2000 - 23:56:07 EST