On 19 Apr 2013, at 19:52, Craig Weinberg wrote:
On Friday, April 19, 2013 9:59:34 AM UTC-4, Bruno Marchal wrote:
On 18 Apr 2013, at 22:05, Craig Weinberg wrote:
On Thursday, April 18, 2013 1:29:29 PM UTC-4, Brent wrote:
On 4/18/2013 8:15 AM, John Clark wrote:
On Wed, Apr 17, 2013 meekerdb <meek...@verizon.net> wrote:
> It's been proposed that the susceptibility to mutation is itself
a characteristic subject to natural selection.
If a animal is undergoing stress (too hot, too cold, too thirsty,
too hungry whatever) that means there is something about it that
is not well adapted to its environment; I can imagine a gene that
in times of stress would switch on and produce a chemical that
increases the rate of random mutation in the genes of the
offspring of that stressed animal. Most of the offspring would
have mutated in the wrong direction and die but they would have
probably died anyway because they would have been as poorly
adapted as there parent was, but if the mutational effect was not
too strong (even if it's in the right direction you can change
things too far) it could increase the likelihood that at least one
of its children would be better adapted than its parent.
However I maintain that such a stress induced mutation producing
gene has had no significant effect on the history of life, at
least not in animals that reproduce sexually.
That's a kind of Lamarckian adjustment of mutability. What I was
referring to is simple Darwinian adjustment of mutability. There
are error correcting mechanisms for DNA reproduction. Suppose they
worked perfectly: then there would never be any genetic variation
and when the evironment changed the species would go extinct. But
if they had a slight error rate then there would develop a range of
genetic diversity that might, under environmental change, result in
survivors or even new species. So on strictly Darwinian theory the
DNA error correction may be selected to be less than perfect.
How does a deterministic universe invent something which is
intentionally less than perfect? I'm not saying that it couldn't,
or didn't, but why would there really even be any possibility of
volatility built into physics in the first place? What, in a
deterministic universe, constitutes an 'error'?
A deterministic reality might be unable to make an error at the
"bottom level", but if it can emulate high level complex processes,
like running some complex software, and such software can make an
error with respect to the goal (like "survive"). Look at some
youtube "crash investigation" showing why today some plane crash are
due to computer errors. The error can have multiple origin, hardware
or software.
Likewise it is reasonable for a biologist to say that when a DNA
polymerase introduces an unwanted supplementary nucleotide, it is
making an error. In fact living cells contains a lot of error
correction code to handle such cases, with 'error' taken in a sense
similar to the one used in computer science. This illustrates that
some errorless low-level can support higher level errors.
Bruno
It seems like you are bringing in empirical evidence of errors in
the real world and using that to justify the expectation that at
some point between low-level and high-level, this 'error' potential
emerges as a condition of complexity.
OK.
What I am asking for though is precisely that this point be
explained by theory. What is the theory of the emergence of the
first error?
It is when god put the tree of knowledge in the garden :)
More seriously, it is when universal machine/number begins to refer
and self-refer. That ability makes it possible to accelerate the
computations relatively to each other, but entails the possiblity of
error.
The deep reason is already contained in Gödel's second incompleteness:
if I am consistent then it is consistent that I am inconsistent (Dt ->
~BDt). Simple but rich correct theories can be come inconsistent, or
consistent but unsound.
Bruno
Craig
Craig
Brent
Such a stress-mutation gene has never been found in a sexual
animal and it's easy to see why. In sex all the genes are not
inherited in one big package but are shuffled around with the
genes of the other parent, so a animal that was lucky enough to
inherit the good genes produced by the hypothetical stress-
mutation gene but not the stress-mutation gene itself would do
just as well or better than a animal that got both the good genes
and the stress-mutation gene that is no longer active because the
animal is no longer under stress. So even if such a stress-
mutation gene did occur in one individual in a population it would
vanish in just a few generations from the gene pool. Natural
Selection doesn't figure "I better keep that stress-mutation gene
because even though there is no stress now that could change and
such a gene might come in handy in the future". Evolution has no
foresight and can't think and all that matters to it is what's
happening right here right now.
John K Clark
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