[Taxacom] chimp-gorilla clade is not being seriously debated

John Grehan jgrehan at sciencebuff.org
Fri Jan 14 15:13:41 CST 2011



-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Thursday, January 13, 2011 10:39 PM
To: taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] chimp-gorilla clade is not being seriously debated

"Hi John,
     Frankly I am annoyed by BOTH sides of this debate."

I am not. The annoyance I was referring to was that not a few in the
primate/human evolution field are annoyed that the orangutan question
won't just disappear.


"My conclusions
are not simply based on single base changes, but heavily on larger-scale
insertions or deletions (sometimes even hundreds of thousands of bases
long), so your argument misses the mark if you are directing such
criticisms at me."

I did not make a criticism, but just noted exactly what you said above -
that if one believes in the infallibility of DNA matching then there is
no room for any alternative possibility.

"On the other side, are some who do still rely too heavily on such
simplistic single base changes.  I agree with you that doing that to
support an exlusive chimp-hominid clade seems ill-advised."

My comments were general regardless of that nature of the DNA sequence
patterns.
       
"However, I am increasingly convinced that both sides of that
debate are WRONG.  It could very well be that NEITHER an exclusive
chimp-hominid clade NOR an exclusive orangutan-hominid clade is correct.

      The more I look into it, the more likely seems the third topology:

    orangutan (hominids (chimp, gorilla)."

Anything is possible
   
"Thus the molecular similarities of hominids with a probable
chimp-gorilla clade seem plesiomorphic for the hominid-African ape
clade, and the morphological characters (by which you seemed equally
swayed) are plesiomorphic for all great apes."

At this time I am more inclined to view the morphogenetic evidence at
face value - that humans and orangutans share more uniquely in common
and are therefore more likely to be sister taxa to the exclusion of
African apes.
    
"The result is a fruitless debate which continues to ignore the
third possibility, that chimps and gorillas clade together, with
hominids splitting off before them, and orangutans splitting off before
that Afircan clade."

Nothing is ignored in the morphogenetic argument. Any corroborated
features that give this pattern would be included in our analysis.
                
"If you look at all the evidence, morphological and large-scale
molecular evidence (LINES, SINES, and even broader chromosomal
structure), an exclusive  chimp-gorilla clade seems increasingly
likely."

That remains to be seen. 

"Thus I see the advocates of a chimp-hominid clade as extremists on one
side, and advocates of an orangutan-hominid clade as extremists on the
other side, and that both extreme views could easily be wrong."

They are just different alternative interpretations of the evidence.
Nothing particularly extreme about that.
    
"When such extremes continue to butt heads, I always wonder if
both sides only have it half right (and thus half wrong)."

Its always possible 

"The real goal
is to get it ALL right, and I can only hope that you eventually see that
it is in your best interest to challenge the exclusivity of a supposed
"chimp-hominid" clade." 

?? That is what we are doing.

"If you continue betting on an exclusive
orangutan-hominid clade, I think you inevitably face disappointment."

That is indeed the risk of anyone challenging the majority view.

"But then I think the majority who favor an exclusive chimp-hominid
clade
could also be in for a big surprise.          
       Neither single base changes nor simple morphologies will provide
the final answer.  The real answer lies in complex, large-scale,
molecular morphologies (SINES, LINES, and other larger-scale chromosomal
structures).  In other words, molecular morphology at a large scale upon
which not enough people are basing their main conclusions."

We shall see one way or another perhaps. Thanks for the obserations

John Grehan
      
       ---------------Ken Kinman                        
----------------------------------------------------------
John Grehan wrote:
        Naturally if one believes in the infallibility of DNA base
sequence similarities created by alignment then one would naturally only
be interested in corroborating morphogenetic patterns of similarity. So
far they are lacking. Hence the annoyance of the orangutan evidence.



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