[Taxacom] Robust argument

mivie at montana.edu mivie at montana.edu
Sun Jun 28 08:48:27 CDT 2009


John,

[stepping back, taking a breath and putting on my serious hat]

I do not understand the idea that the Homo-Pongo hypothesis is routinely
ignored?  Indeed when specifically and clearly stated phenetic analyses of
genomic data are used, the Homo-Pan similarity is always highlighted, but
note I said "similarity" which I think we dealt with about 1982 as not
being the same as "relationship."  In that context such things as "share
98% of their genome" and "humans' closest relative" does not mean
phylogenetic relationship but similarity.

I routinely see the phylogenetic relationship stated to be confused and
still being debated when referenced in the scientific literature and
discussions.  Thus, the Pongo+Homo hypothesis is not ignored as you so
often claim.  Of course some arguing one way or the other may pooh-pooh
another argument, but that does  not represent the body of debate.  The
popular press perhaps can be said to get this confused, but that is hardly
the audience addressed here.

I think that the only place you fall down in this discussion is an
apparent do-or-die search for anything that you can raise to support a
previously decided upon truth (Pongo-Homo are sisters).  The scientific
question of what is the living sister of Homo is much more open in the
literature, although really not that interesting to most "Homo-centric"
researchers who concentrate on the fossil search for a sister-group, and
rely 100% on morphology.

Michael



> Bob,
>
> I don't think there should be any trepidation over expressing any point
> of view on TAXACOM. I inserted some comments below which Bob also covers
> at the end. I agree with the questions Bob has raised about the
> assumptions and interrelationships of evidence.
>
> I believe these issues over morphology and molecules have largely put
> away in the closet when it comes to the assertion of molecular theory as
> the be all and end all of evolutionary relationships. One sees this in
> the way the orangutan sistergroup theory has been dismissed as
> "preposterous nonsense" and "loopy"(behind a veil of anonymity of
> course)even though the relationship is based on a fairly standard
> cladistic analysis and for the most part very well documented and
> corroborated apomorphies. Of course someone could come along and
> demonstrate either that these apomorphies for the most part do not
> exist, that our data was wrong, or that they will demonstrate that
> humans and chimpanzees do indeed (and despite the failure to show this
> so far) share far more apomorphic features than humans and orangutans.
> But as long as the orangutan evidence gets ignored there will be no
> resolution either way.
>
> Its been interesting for me, a relative bystander at the beginning, to
> see how often ignoring the orangutan theory was justified by everyone
> ignoring the theory. Perhaps this is another principle of science that
> should be taught to students: Grehan's first theorem of science -
> Ignoring a theory is justified by everyone ignoring it.
>
> Sorry, I apparently lack a sense of humour.
>
> John Grehan
>
>> bounces at mailman.nhm.ku.edu] On Behalf Of Bob Mesibov
>>
>> (1) Because the genome is passed on from generation to generation, it
>> contains information we need to infer evolutionary history.
>
> Perhaps so, but what is the 'information'? A widespread assumption is
> that sequence counting of one form or another represents that
> 'information'. Others have pointed out that the genome is not the only
> thing passed on from generation to generation.
>
>> (2) It is possible to infer evolutionary history using information in
> the
>> genome.
>
> How do we know that? And again in what form does that information take?
>
>> (3) Morphology also contains information of use for inferring
> evolutionary
>> history.
>
> But is morphology separate from the genome?
>
>> (4) It is possible to infer evolutionary history using information
> from
>> morphology.
>
> If (3) is true
>
>> (5) Literally speaking, morphology is not inherited, so morphological
>> information is second-hand data derived from a heritable source: the
>> genome.
>
> Not by itself perhaps, but if morphology is consistently reconstructed
> generation to generation then the process is inherited and there is
> nothing 'second hand' about it. It would seem to be just as much a part
> of the genome as the DNA molecules.
>
>> (6) No other kind of information can be used to infer evolutionary
>> history, because no other information is inherited.
>
> Geography as some have mentioned. And geographic information has
> occasionally been used to predict phylogeny.
>
>> (4) has been the basis for evolutionary inference for a long time, (2)
> for
>> a shorter time. Many people believe that (2) is better than (4)
> because of
>> (5), and because there is more (1) information than (3) information.
>>
>> The logic here needs defending. Why should (5) make (4) any less
> reliable
>> than (2)? (I think this is one of Richard Zander's points.) How do you
>> compare the reliability or resolution of (2) vs (4), given that we
> have no
>> time machine and no other information (see (6)) that can independently
> be
>> used to infer past events? How do you know that there is more
> independent
>> information from (1) of use for historical inference than from (3)?
>>
>> I think these 3 questions go to methodological assumptions. Should
> these
>> assumptions be taken as givens, equally reliable from group to group?
> It
>> worries me that posters have written THEORETICALLY in caps without
>> spelling out their thinking.
>>
>> I also point to (6), which is nonsense, and comes from thinking about
>> organisms divorced from their geographical location and their
> ecological
>> associations (think of parasitism, insect/host plant interactions,
> etc).
>> (6) should not be confused with (7), which might read "It is possible
> to
>> infer evolutionary history from biogeography and ecological
> associations."
>> That history might be blurrier than (2) and (4) histories, but how do
>> total evidence enthusiasts justify their insistence on using (1) and
> (3)
>> evidence to the exclusion of (6) evidence? (Or is it just that *some*
>> evolutionary historians can't be bothered studying all the
> phenomenally
>> complicated, ungeneralisable facts of what used to be called natural
>> history?)
>> --
>> Dr Robert Mesibov
>> Honorary Research Associate
>> Queen Victoria Museum and Art Gallery, and
>> School of Zoology, University of Tasmania
>> Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
>> (03) 64371195; 61 3 64371195
>> Website: http://www.qvmag.tas.gov.au/mesibov.html
>>
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