On Tue, Aug 13, 2013 at 12:01:52PM -0400, John Clark wrote:
> On Mon, Aug 12, 2013  Russell Standish <li...@hpcoders.com.au> wrote:
> > The central dogma of molecular biology deals with the detailed
> > residue-by-residue transfer of sequential information.
> Yes, but we're not talking about molecular biology, we're talking about
> Evolution and it has a different central dogma.
> > > It states that such information cannot be transferred back from protein
> > to either protein or nucleic acid.
> I know of no example of a change in a protein making a systematic
> repeatable change (as opposed to a random mutation) in the sequence of
> bases in DNA that are passed onto the next generation.

Epigenetic information is expressed by the presence or absence of
methylation of the bases, not the sequence.

> > Not all evolutionary processes have the central dogma
> >
> So what? As I said before, Darwin knew nothing about DNA or proteins or
> epigenetic changes and he didn't need to; he knew nothing about the details
> he only knew that there were hereditary factors of some sort that were
> passed from one generation to the next, and because no process is perfect
> he knew that there would sometimes be changes in that information, and he
> knew that some of those factors would reproduce faster than others, and he
> knew that the thing that would determine the winning factors from the
> losing factors is natural selection.

Sure, I'm not arguing that epigenetic, prebiotic or cultural evolution
shouldn't be called "Darwinian". But in that case, Lamarkian evolution
is also "Darwinian", and sometimes people want to draw that
distinction, so the adjective "Darwinian" become a bit ill-defined and

Any process satisfying Lewontin's 3 criteria I would call
evolution. If any of the criteria are not satisfied, I would use a
word like "process", such as "irreversible process", or whatever.

> > > What it means is that lessons learnt by the body (ie protein) cannot be
> > transferred back to the genome (ie DNA). It is the antithesis to
> > Lamarkianism. Epigenetic changes involve changes of the genome by the body
> Epigenetic changes do not change the sequence of bases in DNA, and more
> important I see no evidence that the body has learned any lessons. I see no

Epigenetic changes show that there is more to hereditary information
than base pair sequence.

> evidence that epigenetic changes are more likely to happen in the direction
> of greater adaptability rather than the reverse. All I see is the
> environment causing random changes in hereditary factors that, like all
> changes, are more likely to be harmful than helpful.
> > > How significant epigenesis is to evolution is another matter, of course.
> >
> Well Darwinian Evolution was what we are talking about! 

Well, actually, what we started talking about was prebiotic evolution,
the possibility of evolving an oprimised standard genetic code, to be precise.

> At most all
> epigenesis does is provide a new source of variation for Darwinian Natural
> Selection to work on; and if those changes don't persist through many
> generations then epigenesis can't even do that.
> > Obviously, there is no equivalent central dogma in cultural evolution.
> >
> The central dogma of Evolution, both biological and cultural, has nothing
> to do with DNA or proteins or epigenesis. The central dogma of Evolution is:
>  1) Heredity factors exist.
>  2) The process that transfers those factors is very reliable but is not
> perfect and so sometimes they change.
>  3) Because there are more ways to be wrong than to be right most (but not
> all) of those changes are harmful.
>  4) Some of those changed heredity factors will reproduce faster than
> others and become dominant in a population.

Provide one citable source where the author uses the term "central
dogma" to describe the above (which is a somewhat poor paraphrase of
Lewontin's 3 criteria of evolution).

> The discovery of epigenesis does not in any way challenge the central dogma
> of Evolution.

Only if you redefine the term "central dogma" to mean something
else entirely, my Humpty!


Prof Russell Standish                  Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Professor of Mathematics      hpco...@hpcoders.com.au
University of New South Wales          http://www.hpcoders.com.au

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