[Taxacom] hominid challenge and Pavetta challenge

[John Grehan]

I agree with this point, that individual morphological characters bear scrutiny. From my perspective (with which others may disagree), a prima face 'good' or 'reliable' character is one which is uniquely shared among some of the members of the ingroup, and better that it is a distinct character than a morphometric measurement (although both have been used in the orangutan analysis). But that's just a subjective point of view so I claim no necessary superiority in that.

I think the molecular-morphological incongruence provides an opportunity for taking the closer look, but specialists in the field (of human origins) have until now largely avoided that opportunity. 

John Grehan

  


> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Barry Roth
> Sent: Wednesday, September 23, 2009 8:09 PM
> To: Taxacom
> Subject: Re: [Taxacom] hominid challenge and Pavetta challenge
> 
> Yes, and the further question is, how do we decide in what cases
> morphology is (or, more specifically, what characters are) reliable?
> 
> I have enjoyed, for instance, comparing the results of molecular and
> morphological analyses of some groups of snails.  Some morphic characters
> long relied on by systematists were incongruent with the results based on
> DNA sequences.  Hmm, that was good to know, perhaps those are "shallow"
> morphic characters.  Others, that many of us had long written off turned
> out to sort rather congruently.  Ahh, worthy of a closer look; maybe we
> didn't parse those character-states well enough.  I consider this process
> of cut-and-fit to be sound, pragmatic systematics.
> 
> But should we accept one data set (e.g., molecules) as always
> determinative in this process?   Similarly, should geography tilt the
> balance between two otherwise equally weighty interpretations of
> relationship based on morphology?  To do so algorithmically in either
> situation is to take a fairly hard stance, it seems to me.
> 
> Barry Roth
> 
> --- On Wed, 9/23/09, Stephen Thorpe <s.thorpe at auckland.ac.nz> wrote:
> 
> 
> > if we accept, on the basis of molecular results, that morphological
> evidence is unreliable
> NOT ENTIRELY UNRELIABLE IN EVERY CASE! Morpho- evidence is likely
> reasonably reliable in most cases. A few cases where morpho- evidence
> (allegedly) gives the wrong answer doesn't mean it is totally unreliable
> in every case ...
> ________________________________________
> From: taxacom-bounces at mailman.nhm.ku.edu [taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Barry Roth [barry_roth at yahoo.com]
> Sent: Thursday, 24 September 2009 11:30 a.m.
> To: Taxacom
> Subject: Re: [Taxacom] hominid challenge and Pavetta challenge
> 
> It's not up to me to answer on behalf of John, but I take his question as
> a serious methodological one:  if we accept, on the basis of molecular
> results, that morphological evidence is unreliable, how can we turn around
> and, in a case where molecular data are unavailable, accept the available
> morphological evidence as trustworthy?
> 
> I suppose this could be justified as "you work with what you've got," and
> that is of course a familiar situation for paleontologists.  But if a
> whole modality of data is dismissed as unreliable, then you shouldn't be
> able to cherry-pick the situations where you accept and trust it.  At
> least not if consistency -- rather than special pleading -- is considered
> a virtue in phylogenetic analysis.
> 
> Barry Roth
> 
> --- On Wed, 9/23/09, Stephen Thorpe <s.thorpe at auckland.ac.nz> wrote:
> 
> 
> 
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