44th human-orangutan synapomorphy

Richard Jensen rjensen at SAINTMARYS.EDU
Fri Jan 14 08:53:58 CST 2005

In standard phylogenetic practice, if a character state is a plesiomorphy
for a clade, then its presence in only some members of the clade is
uninformative with respect to relationships among those members retaining
the character state in question.  Thus, if mechanical ability is a
plesiomorphy for primates, then its retention by orangs and humans cannot be
a synapomorphy supporting their being sister taxa.  That's what I meant and
I suspect that's how Ken interpreted what I wrote.



John Grehan wrote:

> > Behalf Of Ken Kinman
> > Sent: Friday, January 14, 2005 11:49 AM
> > Subject: Re: [TAXACOM] 44th human-orangutan synapomorphy
> >
> > John,
> >      I'm pretty sure that is not what Richard was suggesting.  And I
> don't
> > think it is a very reasonable possibility.
> Richard posted his thanks for Ken's recognition of what he [Richard] was
> trying to communicate, but the above doesn't tell me anything. Richard
> stated "I suggest that mechanical ability is a plesiomorphy, having
> arisen much earlier in the animal kingdom." If the feature is a
> plesiomorphy for primates then it would seem to me that its occurrence
> in humans and orangutans would have to be attributed to the feature was
> retained from the primate ancestor and so its absence in other primate
> groups would have to be attributed to loss of the feature. Where did I
> go wrong in my interpretation?
> I do think it is reasonable to
> > conclude that many of your proposed synapomorphies are plesiomorphies
> (or
> > other homoplasies), and thus my suggestion that orangutans and
> hominids
> > could occupy adjacent clades rather than clading together (as you
> > propose).
> It would seem to me that the synapomorphies do not prevent one from
> placing orangutans and hominids as adjacent clades at all. In fact they
> would have to be adjacent clades. At a higher level they would, of
> course, be placed within an encompassing clade (perhaps Hominidae).
> So in conclusion, I think you might want to heed the advice of
> > not getting "carried away" on your synapomorphy lists.  But somehow I
> > don't think you will, so I give up and am moving on to other things.
> I think you said that once before.
> > However, I strongly suspect you are greatly underestimating the
> mechanical
> > ability of chimps, capuchin monkeys, etc.
> Everything is open to doubt, but it is the specialist literature that
> points to orangutans being mechanical geniuses compared with other
> primates. That's not just me reading something into the literature.
> John Grehan
> >     -- Ken
> >
> > ****************************************************
> > John Grehan wrote:
> >      Richard's suggestion that the mechanical ability is something
> > ancestral to primates and lost in all groups except orangutans and
> humans
> > is a reasonable possibility.

Richard J. Jensen              | tel: 574-284-4674
Department of Biology      | fax: 574-284-4716
Saint Mary's College         | e-mail: rjensen at saintmarys.edu
Notre Dame, IN 46556    | http://www.saintmarys.edu/~rjensen

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