[Taxacom] Morphological molecular reconciliation again (was erecting or sinking higher taxa

John Grehan calabar.john at gmail.com
Sun Oct 14 10:12:42 CDT 2012


I'll take a bite at this.

On Sun, Oct 14, 2012 at 9:51 AM, Richard Zander <Richard.Zander at mobot.org>wrote:

> Hey, I think I have a solution to the orangutan/homo problem proposed by
> John Grehan many times over the years.
>
> Basically, a pattern is not an explanation. We all know that, don't we,
> given Fizhugh's work? Cladists have two patterns and they usually just
> discard one as being not up to snuff.
>
This situation is equally applicable to any kind of systematics where one
pattern is rejected in favor of another. I am not aware that 'cladists'
'usually' do this any more than any other (what?) method.


> Here is a conciliation of the orangutan problem (i.e., orangs are closer
> to humans in morphology, yet farther from humans than chimps and gorillas
> in molecular data).
>

Molecular sequence data. The morphology is also molecular, only the
molecular expression of the morphology has not yet been identified.


> Suppose that there is an orangutan sister group to humans that is now
> extinct.


If this extinct sister group is closer to humans than orangutans, and
therefore an extinct sister group to humans, it is not an orangutan
sistergroup since that entity would encompass all living and extinct taxa
comprising the human clade, and those comprising an orangutan clade.


> This makes both morphology and molecular data supportive of the same
> explanation of the apparently conflicting cladograms. The extant organ
> clade is an isolated remnant of a wide-spread orang distribution that
> generated the chimps then the gorillas then you and me.
>

This seems to be a rewording of a classic explanation, that all the
human-orangutan synapomorphies are just plesiomorphies from a common
ancestor of humans and the great apes. It is an 'explanation' used to
explain away the morphology in favor of the molecular sequence similarities.


>
> One may now ask, where is the evidence? like fossil orangs in Africa, etc?
> How should I know?


Well one would know, from reading the Grehan & Schwartz (2009), that their
are orangutan-like teeth in Africa that are mislabelled Australopithecus,
and australopiths themselves might be considered bipedal orangutan-like
hominids.


> BUT we now have a scientific explanation of conflicting patterns that can
> be investigated.
>

I am not able to see how the 'explanation' is any more scientific than any
other. We are still left with an unresolved conflict between molecular and
morphogenetic similarities. Morphogenetics points to orangutans as our
closest living relatives and the fossil hominid record is congruent with
this conclusion. Molecule similarities give a different result, but given
their phenetic character in original character state designation, and in
analysis (such as with retrofitting genes of unequal size) it is my opinion
that the molecular sequence similarity pattern is more problematic. Just an
opinion of course.

This problem is not limited to hominid origins.


> Patterns are not explanations.
>

Does it matter either way?

John Grehan

>
> Comments?
>
> _______________________
> Richard H. Zander
> Missouri Botanical Garden
> PO Box 299
> St. Louis, MO 63166 U.S.A.
> richard.zander at mobot.org
>
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