WRE>[...]
DJT>This is because determining our "genetic makeup" is not a
DJT>case of creating new information.
WRE>[...]
WRE>If the statement above were modified to "... not necessarily a
WRE>case of ..." it would be unexceptionable. But the process of
WRE>reproduction in humans is not simply a matter of drawing a set
WRE>of alleles, like cards from two decks, from each parent, even
WRE>when one excludes the usual potential for point mutations to
WRE>occur. Recombination does not respect reading-frame
WRE>boundaries.
DJT>Are you referring to the phenotype? [In which case, I
DJT>agree]. Or are you referring to the genotype? [In which
DJT>case, I do not "see" an information change].
Given that the topic was "genetic makeup", I think it is
pretty clear that I was referencing the genotype. It is clear
that we disagree over whether information can be said to
change, and possibly represent a novelty, in the course of
determining a new human genotype. The point of the
discussion, I presume, is to figure out what our disagreement
stems from.
DJT>When you use the words "possible outcome", are you making
DJT>a deductive statement, or can this be justified by
DJT>empirical evidence?
How about a deductive statement that has the possibility of
being tested by empirical inquiry? The characterization of
recombination is grounded in the results of empirical inquiry
into its mechanisms. We know what recombination is and does
via studies like those conducted on Neurospora spp. We know
that it does not respect reading-frame boundaries from such
studies, and thus does not necessarily preserve alleles intact.
DJT>I am not just quibbling over words.
Ok, I can accept that. I'm using Shannon as my source for
a definition of information. The measure of information I
am using is quantified as
H = - sum_i( p_i log p_i )
where the summation is over all i symbols in a message, where
p_i is the probability of the symbol appearing in the message.
What's your relevant definition of "information" and what is
its quantification method? Perhaps our differing views are
simply due to a mismatch in what we each mean by information
and the way in which each of us is measuring that information.
DJT>The vast majority [if
DJT>not all] of the variation in living things noted by Darwin
DJT>related to phenotypic expression rather than genotypic
DJT>changes. Those who extrapolate plant and animal
DJT>variations due to artificial breeding and argue for
DJT>"macroevolutionary" change are making the same category
DJT>mistake.
What do these musings have to do with the claim that the
process of determining an individual human's genetic makeup
cannot introduce new information? It looks like a complete
non sequitur to me.
WRE> Theoretically, in the presence of sufficient base-pair
WRE> diversity, a series of recombination events can produce the
WRE> same result as a series of point mutations, or a single point
WRE> mutation.
DJT>Theoretically, I will concede this point. But I will
DJT>suggest that it is not particularly helpful, as it does
DJT>not convey the reality of what is going on with either
DJT>recombination or mutation.
The reality of what is going on is what we are trying to get
at, but certain claims that are false must be disposed of
along the way. Among them is the false claim that
recombination cannot produce the same kinds of changes as
point mutation. It can.
WRE> There is no theoretical basis upon which to divide
WRE> recombination and point mutation as possible information
WRE> sources.
DJT>I suspect this conclusion is highly controversial amongst
DJT>evolutionary biologists. The only way I can agree with it
DJT>is to add that neither recombination nor mutation are
DJT>possible information sources and so the two processes
DJT>cannot be divided on this account.
The conclusion that both recombination and point mutation are
possible information sources is, I assure you, far from
controversial among biologists. What I said above was not
meant to indicate that the typical results of the processes
were indistinguishable (cf. comment by Lundberg), but rather
to counter the claim that the two processes differed in their
potential for generating new information.
Wesley