"Tim Tyler"  wrote in message
news:c8mdpf$253n$1{at}darwin.ediacara.org...
> Perplexed in Peoria  wrote or quoted:
> > Maintaining analog information close to an environmentally specified
> > optimum can be done using selection, but it takes a huge cut out
> > of the reproductive excess.  It is far better to have digital
information
> > that is "usually" reproduced exactly, and then to only
use selection to
> > deal with the exceptions to that "usually".  That seems to take a
> > much smaller cut.
>
> Dawkins once wrote a pop-sci piece (in River Out Of Eden, Ch.1, The
> Digital River) about the wonders of digital inheritance (vs analog
> inhertance).
>
> His thesis at the time - IIRC - digital was better than analog - and that
> was why we had digital genes, and that was why we have digital TV, music
> and movies - and that was why all organisms everywhere in the universe
> will use digital information storage media for their genes.
>
> This is all very well - but analog media are not as bad as all that -
> since you can fairly easily use them to simulate digital media.
>
> It *certainly* doesn't need selection to compensate for the
> deficiencies of storing information in analog media - since
> you can effectively change an analog medium into a digital one
> by simple tricks such as forcing all low values to zero - and
> all high values to one.
>
> There *is* a cost in doing this - but it doesn't have to be paid
> in terms of selection and dead offspring - it can be paid by sacrificing
> some of the information storage capacity in the device in question.

The point that you are missing is that this is not a one-time cost
in decreased storage capacity.  It is a continuing cost that must
be paid by the organism both in greater energy usage during
its lifetime, and in decreased viability (selection).  There are costs
to be paid over time whether you choose analog or digital, but
if you choose analog, you don't really have the option of paying
in energy - you are pretty much stuck with selection as the
currency in which you will have to pay the price.

For digital information, if you want to put your information into a
long-term storage format, you will have to pay an energy price
each time you read, and a hefty price each time you write.  But
simply letting the information sit there can be fairly cheap, as
long as you don't need to consult it or refresh it.  But there is a
trade-off - the best long-term storage media involve a high
energy-per-bit, hence they are expensive to refresh.  Furthermore,
if you want to use redundancy to increase long-term accuracy, then
you have just introduced another refresh cycle.

Organisms using the digital medium of DNA are using a moderately
long term medium, so they pay costs for reading (transcription),
writing (replication), and redundancy (translation and recombination).

Analog information (outside biology) cannot be "resharpened" by
copying.  So, the only way to store it long term is to use a very
high energy per bit and then to rarely read it - because the very
act of reading degrades the information.  Furthermore, the kinds
of information - time series - that is sometimes stored in analog
format is not the kind of information that is most useful in biology.

So, AFAIK, the only use of analog information in biology is
short-term.  Signal transduction (cyclic AMP and all that) is
analog.  Over a shortly longer time frame, plants store analog
information for the lifetime of the organism - a bonzai remembers
how it was tortured and an aspen grove remembers where on
the hillside the competition is too fierce.

> So: if you have an analog information-storage medium, don't despair:
>
> Despite Dawkins' warnings about the evils of blending inheritance -
> and how organisms everywhere will use digital storage media - you
> can still build perfectly good organisms out of an analog information
> storage medium.

I would like to see that design!  Presumably you intend to use
homunculi to encode development information in the egg and
sperm?  Which of the two homunculi of the zygote do you use
for development?  Or, perhaps these organisms are meant to
be asexual.

This is a stretch, but there is a sense in which each year's
growth in an oak tree is new organism, descended from the
organism of the previous year's growth.  This new organism
inherits its shape from its parent.  Analog information transmission
between generations - if you want to call it that!  But I wouldn't
want to base long term evolution on something like that.
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 5/22/04 10:35:30 PM