[Taxacom] Schwartz and Grehan (2009) cited on Dinosaur Mailing List

John Grehan jgrehan at sciencebuff.org
Tue Sep 13 09:30:08 CDT 2011


The problem with the various molecular patterns being congruent is that
the congruence may not necessarily lend any greater weight if they are
based on the same kinds of assumptions. As for morphology (really
morphogenetics) it is not a 'single' source, but multiple developmental
genetic systems.

With respect to the Yunis and Prakash paper, Schwartz (1987) noted the
following:

Humans and orangutan have in common chromosome 5, a particular pattern
of 12 and 19, and most of Yq, the lower extent of the Y (male sex)
chromosome. 

The chimpanzee and the gorilla also share four apparently homologous
chromosomes - another configuration of 12, 19, 20, and 21 - but with
different banding patterns from those which distinguish chromosomes 12
and 19 in humans and orangutans.

Without at least the gibbon for comparison, one cannot begin to get any
insight into which banding pattern on any given chromosome is derived
for the hominoids. But we are left with the tantalizing hint of support
for the unity of humans and orangutans as well as for chimpanzees and
gorilla

John Grehan

-----Original Message-----
From: Kim van der Linde [mailto:kim at kimvdlinde.com] 
Sent: Tuesday, September 13, 2011 10:06 AM
To: John Grehan
Cc: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Schwartz and Grehan (2009) cited on Dinosaur
Mailing List

John,

I have been working on drosophilid phylogenies for a while, and I have 
seen the whole range of sources that have been used. When I see plain 
basepair phylogeny be congruent with chromosome banding phylogenies, 
being congruent with isozyme based phylogenies being congruent with 
indel patterns being congruent with gene duplication patterns being 
congruent with internal morphology, I am convinced that the mismatches 
in the external morphology are not going to be better than the rest. I 
see a similar pattern with the great ape discussion. The DNA phylogeny 
is congruent with chromosome banding patterns for example. If you want 
to show that several sources of information are all incorrect and the 
morphological evidence is superior, you have to show how those 
similarities arose to the point that they are misleading for the actual 
family history. Yes, when you have multiple sources claiming one thing 
and one source the opposite, it becomes an extraordinary claim requires 
extraordinary evidence situation.

Just one example: Yunis, J. J., Prakash, O., The origin of man: a 
chromosomal pictorial legacy. Science, Vol 215, 19 March 1982, pp. 1525 
- 1530

Kim


On 9/13/2011 9:49 AM, John Grehan wrote:
> It's a bit meaningless to say that "extraordinary claims require
> extraordinary evidence". What is the extraordinary claim here? Is it
any
> less extraordinary to assert that base sequences provide the answer
than
> anything else?
>
> As for the chromosomal rearrangement patterns, what sources are your
> referring to and what evidence specifically?
>
> John Grehan
>
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kim van der
> Linde
> Sent: Tuesday, September 13, 2011 9:41 AM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Schwartz and Grehan (2009) cited on Dinosaur
> Mailing List
>
> Well, I always liked the chromosomal rearrangement patterns the best
as
> evidence for human-chimp, especially chromosome two that is most
similar
>
> to the chimpanzee chromosomes. Really, parallelisms are so common that
> you need far more than some morphological similarities to be able to
> reject the results of many thousands of base-pairs, in-dels,
chromosome
> inversions etc. Extraordinary claims require extraordinary evidence.
>
> Kim
>
> On 9/12/2011 11:26 PM, Kenneth Kinman wrote:
>> Dear All,
>>          I was catching up on postings at the DML (Dinosaur Mailing
> List),
>> and one last week caught my eye.  It cites the paper by Schwartz and
>> Grehan (2009) challenging the exclusivity of a supposed chimp-hominid
>> clade.  Although the poster has reservations about the paper's
>> conclusions, he does make some interesting observations (as does Greg
>> Paul, whose posting he is responding to).  However, one thing that he
>> fails to point out is that Schwartz and Grehan, 2009, do not produce
>> even a single molecular character to support their proposed
>> orangutan-hominid clade, which in my mind is it biggest shortcoming.
>>          Therefore, if Schwartz and Grehan cannot produce any
molecular
>> evidence to support an orangutan-hominid clade, and the molecularists
>> cannot produce convincing morphological evidence for a chimp-hominid
>> clade, then I still feel that hominids most like did not exclusively
>> clade with either of them, but that they are sister group to a
>> chimp-gorilla clade.
>>          It seems that symplesiomorphies are relatively easy to find
> among
>> greats apes, but finding true synapomorphies (molecular or
>> morphological) for its subclades is no easy matter.  I have little
> hope
>> of relevant fossil finds shedding much light on the debate anytime
> soon,
>> but whole genomes (especially certain LINES contained therein) will
> soon
>> make considerable progress in resolving this debate.  Anyway, for the
>> DML postings (for what they are worth), see the weblink below.
>>             -----------Ken Kinman
>>
>> http://dml.cmnh.org/2011Sep/msg00030.html
>>
>>
>>
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>

-- 
http://www.kimvdlinde.com




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