[Taxacom] hominid evidence

John Grehan jgrehan at sciencebuff.org
Tue Jun 30 15:49:28 CDT 2009


David, 

I agree with the summation that this issue concerns the question of how
to
decide which molecular and morphological data are most reliable as
indicators of phylogeny in any given case. Right now there is no recipe
to decide. The two factors that make me more inclined towards the
morphology for the orangutan theory is that there are so many more
apomorphies for humans and orangutans, and the morphological evidence is
also repeated in the fossil record.

I am not aware of any uniquely shared hair and skin color traits for
humans and African apes. Can you elaborate?

John Grehan


> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Dr. David Campbell
> Sent: Tuesday, June 30, 2009 12:03 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] hominid evidence
> 
> > it seems obvious that both morphological characters and DNA bases
> > are... characters. Each being one "evidence" as such.<
> 
> Additionally, both are subject to potential sources of error (in
regard
> to their pointing to the correct phylogeny) such as convergence,
random
> similarity, shared ancestral features, researcher error, etc.  There
> are indubitably molecular data that favor a human-orang grouping and
> some that would favor a chimp-orang grouping, just as there are
> morphological and behavioral features that support a chimp-human or
> chimp-orang grouping.  (As this concerns a small cluster of highly
> derived deuterostomes rather than more interesting lophotrochozoans, I
> have not followed the details very closely, but an obvious
> morphological link for humans to chimps and gorillas is hair and skin
> color; in behavior, there's the new study of tickle-induced laughter.)
> 
> This isn't really a morphology versus molecules issue (though the fact
> that people can specialize in molecular work without a clue on the
> morphology can make it look that way), but rather a question of how to
> decide which molecular and morphological data are most reliable as
> indicators of phylogeny in any given case.
> 
> --
> Dr. David Campbell
> 425 Scientific Collections Building
> Department of Biological Sciences
> Biodiversity and Systematics
> University of Alabama, Box 870345
> Tuscaloosa AL 35487-0345  USA
> 
> 
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