[Taxacom] chimp-gorilla clade is not being seriously debated
jgrehan at sciencebuff.org
Sat Jan 15 08:49:50 CST 2011
All evidence is taken 'at face value' (including DNA sequence similarities) until something comes up to challenge that.
True - not all shared characters are synapomorphies. That is why one does an analysis (in morphogenetic studies) to construct the tree to determine which uniquely shared similarities give the best corroborated pattern of relationship. Unfortunately, with DNA sequence data, one has to build the tree before being able to identify the putatively uniquely shared similarities since there is no way to do this beforehand for each character since there are only four characters that replace each other rather than different character states as in morphogenetics.
There is nothing empirical to suggest that its 'riskier' to reject molecular data such as LINEs and SINEs any more than it may be riskier to reject the morphogenetic data. The history of molecular analysis has been one of constantly jumping from one technique to another as each new one is announced to be the silver bullet as each former is found to be inadequate in one way or another. Its an irony to see so all the sequence studies proclaimed on one hand, to be sufficient falsifier of morphogenetics, and proclaimed on the other by the SINE/LINE supporters to be riddled with sufficient problems as to be unreliable. We have commented on the SINE/LINE question in a published article that can be accessed at http://www.sciencebuff.org/research/current-research-activities/john-grehan/human-origins/humans-and-orangutan/
I fully accept anyone's right to assert what they think is best. After all, I do that myself. But I have also published my evidence and arguments in the scientific literature in support of my assertions (both on human origins and on biogeography). Whether these or anyone else's assertions stand up to the test of future evidence remains to be seen.
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Friday, January 14, 2011 6:19 PM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] chimp-gorilla clade is not being seriously debated
I rambled on way too much last night (which I tend to do when I am tired and frustrated). I actually think the whole orangutan debate has been helpful by challenging an exclusive chimp-hominid clade, and that is a good thing if it (hopefully) spurs a
much needed search for evidence of a chimp-gorilla clade.
However, I believe that your taking the morphological evidence "at face value" is risky. Risky because not all shared characters are synapomorphies (and many will probably turn out to be symplesiomorphies or even homoplasies). And it's even riskier if you reject molecular data (like LINEs and SINEs) that could shed light on
whether they are symplesiomorphic or not.
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