Great Apes again (was: Red Ape book...)

[John Grehan]

I appreciate Ken taking the time to take a closer look at the evidence
since it's morphological this will not interest those who have decided
DNA sequence similarity overrules morphological characters) since that
is exactly what the primate systematists should be doing.

My comments are inserted as follows

> -----Original Message-----
> From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
> Behalf Of Ken Kinman
> Sent: Friday, January 07, 2005 1:14 PM
> To: TAXACOM at LISTSERV.NHM.KU.EDU
> Subject: [TAXACOM] Great Apes again (was: Red Ape book...)
> 
> Dear All,
>       After reading the posting on the Red Ape book, I revisited John
> Grehan's potential synapomorphy listings once again.  Quite a few of
those
> listed for a hominid-orangutan clade still appear to be
non-independent of
> one another and could be combined to produce a shortened list. 

It's always possible, and if one ever distills the molecular pathways to
make the case then that is something that I could see being addressed.
Otherwise, it's just a theoretical possibility and one that could be
applied to sequence data as well. For now one can look at the characters
as they stand.

 At the
> same time, evidence for a Pan-hominid clade is downplayed, including
the
> omission of characters such as:  

It is certainly not my intention to 'downplay' or omit characters
(although I would not say that I might have missed some. When it comes
to digesting complicated papers I would be the first to admit the
possibility. However, in my web listing of Pan-Human characters the
following listed by Ken do not appear to apply as being omissions:

(1) axis of ear bones not at an acute
> angle (Shoshani et al. #103); 

This is actually listed for Pan, Gorilla, and Homo, not a Pan-hominid
clade (or even a Pan-Human clade).

(2) upper I2 occlusal edge does not slope
> distally (Shoshani et al. #161); 

Listed for Pan-Homo-Papio. So not valid as a Pan-Homo character.

and (3) basal keel of lower canines
> absent (Shoshani et al. #163).

Listed for Pan-Homo-Tarsius-Pteropus. Again, not a Pan-Human
synapomorphy.
> 
>       Grehan also fails to enumerate characters which unite the
African
> (Gorilla-Pan-hominid) clade to the exclusion of orangutans, and here I
> list just some of the more interesting ones from Shoshani et al.:

Agreed, I have not listed them (yet) on my web site (since they are not
directly about the Pan-human clade which is the critical question
regarding the genetics). However, they have not been ignored by Schwartz
(2004) who comments as follows:

>   (#102) middle ear deepened (more than 8.5 mm)

"First, as Hezy et al admit about human-African ape features, their
comparisons aren't very broad. Other anthropoids aren't compared with
these hominoids, which raises questions about determining what's
primitive and what's derived. Second is the issue of size. Is the middle
ear deep in Gorilla because it's a large animal? Or, if scaled to body
size, would it be shallow for a large animal?"

>   (#104) area of inner ear greater than 50 square mm

Same as 102

>   (#106) strong klinorhynchy (orangutans are apparently even less
> klinorhynchous than gibbons).

"But all Old World monkeys and most New World monkeys are more or less
like African apes and sometimes even humans. Given the widespread
distribution of flexed-down faces [klinorhynchy] among anthropoid
primates (and virtually all prosimians, too), I'm disinclined to
accepted this feature as uniting humans and African apes."

>   (#111) frontal sinus present

This is one I also get from paleontologists. Schwartz notes:
"To summarize, frontal sinuses develop from different areas on the
ethmoid bone in humans and in gorillas and common chimpanzees; they're
typically absent in bonobos, they're found in various Oligocene and
Miocene fossil anthropoids; we don't know if the upward expansion of the
maxillary sinus in orangutans has anything to do with their lack of
ethmoidally derived frontal sinuses; and, judging from some of the
australopith skulls I've studied, it may well be that they were like
orangutans, at least in the configuration of their maxillary sinuses."
[that's another incongruity for fossil hominids not behaving
(morphologically) like African apes]

>   (#114) orientation of zygomatic bone very superolateral

Also in various monkeys. [my observation of the date matrix] No comment
in Schwartz - at least not on the page with the other characters.

>   (#175) postprotocrista of upper dP4 very well-developed

"This feature is not well developed in humans or African apes".
> 
>       In conclusion, even if one only looks at morphological
characters,
> it seems to me that he continues (1) to overstate the case for a
hominid-
> orangutan clade: 

Given the above, it looks like I have not. There are 43 proposed
synapomorphies for humans and orangutan, and only about 7 for humans and
chimpanzees proposed by proponents of the human-chimpanzee clade.

(2) to understate the case for a hominid-chimp clade; 

It seems I did not. The characters listed above for humans and chimps
were also found in one or more outgroups. The African ape - human
characters appear to be invalid.

and
> (3) MOST IMPORTANTLY, failing to seriously evaluate the third
alternative
> that neither of these is correct, and that hominids split off between
an
> orangutan clade and a chimp-gorilla clade.  This third possibility
would
> certainly explain why hominids have similarities to both orangutans
AND to
> the African apes.  

I'll be happy to consider it if the evidence points in that direction.
At present it would seem that it does not. The morphological character
distributions point to an orangutan-human clade sister-group to African
apes (with chimps and gorillas being sister clades).

Ignoring this very viable third hypothesis is something
> that both sides of the debate might eventually regret in retrospect.
I
> must admit that because it is a sort of "middle ground" between those
two
> sides of the debate, it just makes it all the more attractive to me.
In
> any case, this is a three-way debate (NOT just two).

Again, if it is a three-way debate then I want to see the supporting
characters.

Given the character distributions so heavily favoring the orangutan one
would wonder why one would be so skeptical. In Ken's case I presume,
based on past comments, it is because he has decided that genetic
similarity is the proof of the pudding and so any morphological evidence
to the contrary has to have something wrong with it. At least that's my
impression.

John