[Taxacom] cladistics (was: clique analysis in textbooks)
jgrehan at sciencebuff.org
Sun Aug 21 10:23:57 CDT 2011
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
> Perhaps we just have to look a lot harder for fundamental
> morphological transitions within the presumed hominid-African ape
> clade to challenge those of Schwartz and Grehan (which I still believe
> to be symplesiomorphies).
Yes indeed. Perhaps we should run a lottery as to whether this will ever
> Molecular analysis may not be able to "directly" refute and reject the
> proposed orangutan-hominid clade in the near term,
Of course this is at odds with all the molecular authorities who have
established that the chimpanzee relationship is a fact of evolution. How
dare you put that into contestation. Very naughty.
> but I believe it will help resolve whether the chimp-hominid clade is
> as well-founded as most researchers seem to believe (and if it is not,
> that opens the door to more intensive research into an exclusive
> chimp-gorilla clade, which sadly has been relatively neglected by both
> sides in this debate).
Which seems to be a way of saying that something fundamentally flawed
(over the orangutan proof) is somehow going to be useful anyway.
> The fossil record of great apes is so fragmentary that it generates
> more heat than light in this debate (much like the fragmentary fossil
> record of angiosperms).
Actually its not all the bad with respect to 'Homo' and the
australopiths, particularly the latter that show orangutan
specializations rather than chimpanzee.
Most of the problems with the hominid fossil record is the usually
dreadful quality of original papers, the lack of independent
assessments, the withholding of access to holotypes, and the omission of
reference to any contrary information (such as orangutan-like molars
claimed to be australopith). No wonder it's a mess.
> Therefore, as with angiosperms, molecular analysis will probably make
> break-throughs that allow a more efficient search for true
> morphological synapomorphies. Only then will congruency be found
> between molecular and morphological data sets.
Hope is eternal.
Richard Zander wrote:
Again, I suggest that morphological clades and molecular clades
can be different because they are based on different dimensions in
present-day relationships of evolution, thus the refutation of one clade
cannot be done by finding high probability that the other is correct.
Morphologically you can have ((AB)C,D and molecularly ((AC)B,D, and both
are correct if the morphological ancestor of both A and B is C.
C is then postulated as a morphologically primitive taxon surviving into
present time after generating the geographic isolate B then A. This
difference in clades is because DNA continues to mutate but the
morphology can remain in stasis.
Molecular analysis cannot refute or reject the orangutan-homo
morphological evolutionary relationship, assuming the morphological
relationship has been demonstrated by Grehan and Swartz, et al. A direct
analysis, using other data, that might reveal the morphology of the
ancestor of both man and whatever the sister group in morphology is, is
necessary. The present argument is just talking past each other, and
both analyses, if taken separately, are each sciolistic, that is, based
on only partial knowledge.
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