[Taxacom] Fw: John Grehan & great apes

John Grehan jgrehan at sciencebuff.org
Fri Nov 7 06:05:10 CST 2008


I guess I'm a bit confused by the question as I would not 'explain away'
the data any differently from any other systematist. The largest
congruent (in my case cladistic) set of data is viewed as representative
of the phylogeny while the smaller set of incongruent data is viewed as
representing possible plesiomorphy, parallelism, convergence etc. The
case of the spindle neurons is no different. 

Ken says that I ignore the weakness of my own data. I have treated the
data no differently from any standard systematic approach. Features that
are uniquely shared are potential synapomorphies. The main weakness of
some characters is that the outgroup sampling is not known for all
outgroup species (i.e. all gibbons and all Old World monkeys), and that
in some cases descriptive documentation is not as good as one would
like. Some of these weaknesses are indicated in our supplementary data
where we specifically annotate each character for its taxonomic sampling
- which is more than usually found in hominoid systematics (or even
primate systematics in general).

I recall reading an article about neurons in hominoids and probably the
paper Ken mentions. I will check and see. If I recall correctly, the
outgroup comparison was too limited to use the character since there
were not enough species of gibbons or monkeys sampled. But even so, it
might be a solid character and one worth incorporating into the matrix
(in which case I will make sure Ken is acknowledged). 

But one character does not make or break a phylogeny. The same applies
to the external ear. Ken says it must be far more subject to homoplasy,
but that's just speculation. The ear feature (which is remarkably
consistent in humans) matches the human orangutan evidence very nicely.
It is further corroborated by the presence of a transverse bar in
gorillas and chimps that also shows up in gibbons and perhaps some
monkeys, but not humans or orangutans. In addition it turns out that
tarsiers have multiple transverse bars which also occur in many lemurs
and lorises, but no anthropoids, and that is phylogenetically
interesting given the other evidence linking tarsiers with other
prosimians.

I realize that my arguments are tired and old and I apologize in advance
for any aggravation for my unwillingness to let up on my pet subjects
(and I know that my style can also be annoying at times, and sometimes I
am purposefully challenging on a subject). People are welcome to filter
me out, and no doubt some do. That's what individual choice is all
about.

John 

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Robin Leech
Sent: Thursday, November 06, 2008 4:19 PM
To: taxacom at mailman.nhm.ku.edu
Cc: Kenneth Kinman
Subject: [Taxacom] Fw: John Grehan & great apes

Hi Taxacomers,
A message forwarded from my good buddy, Ken Kinman.
John Grehan may want to answer the issues Ken raises.
Robin
----- Original Message -----
From: "Kenneth Kinman" <kennethkinman at webtv.net>
To: <releech at telusplanet.net>
Cc: <jim.croft at gmail.com>
Sent: Wednesday, November 05, 2008 7:48 PM
Subject: John Grehan & great apes


>
> Hi Robin and Jim,
>       Here we go again rehashing Grehan's tired old arguments against
> molecular data and yet ignoring the weakness of his own data.  What I
> would like to know is how he explains away rather convincing
> morphological data such as following:
>       Uddin et al., 2004 (Proc. Natl. Acad. Sci., 101(9):2957-2962)
> studied the morphology of spindle cell pyramidal neurons in the
anterior
> cingulate cortex of the brain.  There is a clear progression:
greatest
> numbers in humans, next greatest numbers in chimpanzees, followed by
> gorillas, and the least numbers in orangutans.  Furthermore, they are
> absent in all other primates (or other mammals).  This correlates with
> not only the numbers of these spindle cell neurons, but their size as
> well:  greatest in humans, followed by chimps, and smallest in
gorillas
> and orangutans.
>        This is an elegant example of morphological evidence which
> corroborates the molecular evidence.  At least it seems much stronger
> than arguments about something as  muddled and unconvincing as
external
> ear morphology which must be FAR more subject to homoplasy and seems
> relatively superficial in any case.


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