From: Derek Gatherer (email@example.com)
Date: Fri 18 Nov 2005 - 13:30:56 GMT
At 12:12 18/11/2005, Scott Chase wrote:
>No one knows how genes calculate the correct sequence of combinations to
>produce complete organisms from a single cell. Given the laws of
>combinatorics, this task would appear to be impossible.
>They used to rely on the abacus, but then calculators were invented ;-)
>You need to read Sean Carroll's _Endless Forms Most Beautiful_. See the
>parts where he talks about genetic switches.
I thought we had disposed of that argument a while back. I pointed
out to Ted that such a combinatorial calculation never needs to be
made, so it's a pseudo-problem (it is in fact yet again Hoyle's
fallacy - the incorrect assumption that evolution has to achieve
complex structures out of chaos). People who commit Hoyle's fallacy
are, in Dawkins' analogy, looking at Mount Improbable and claiming
there's no way up, whereas in fact there is a way - it just takes
billions of years and billions of mountaineers die in the
attempt. But each mountaineer starts out not from the bottom but
from the place the last best dead mountaineer reached.
> I've heard retinoic acid mentioned as a
>possible morphogen and it certainly ain't DNA.
Gosh, retinoic acid! Did part of my Ph.D. on that, many eons ago.
Actually, Ted, try this one:
We know that related organisms have similar DNA sequences.
We know that related organisms have similar developmental pathways.
We know that mutational pressure on DNA is high.
If developmental pathways are controlled by spooky fields and not
DNA, then since mutational pressure is high, we would see a lot more
divergence in DNA. Since we don't, it follows that developmental
pathways are not controlled by spooky fields. QED.
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