[Taxacom] hominid evidence

[Kenneth Kinman]

Hi David,
       Highly apomorphic taxa (like humans) are indeed problematic when
strictly cladistic aversions (paranoia?) are applied.  Like most
obsessive-compulsives, we should continue to encourage them to confront
their fears.  That's been my hope for many years, that they can be
convinced that the world isn't going to come to an end if they recognize
some paraphyletic taxa here and there.         
      Family Hominidae as an exgroup of a paraphyletic Family Pongidae
is a perfect example.  It really doesn't matter if Family Hominidae is
sister group to (1) only the chimp clade; (2) a chimp-gorilla clade; or
even (3) an orangutan clade.  In all three cases, Family Pongidae has
the same traditional content, and the true phylogeny (once confirmed by
whole genomics and further confirmed by appropriate morphologies) can be
reflected by exgroup coding (as used by myself or Michael Benton).  I
suspect that my classification will then continue to code Hominidae as
sister group to a chimp clade, or switch to being shown as sister group
to a chimp-gorilla clade (the second most likely outcome in my opinion).
If there actually is strong genomic evidence for a human-orangutan
clade, I could easily code for that as well, but I really don't expect
that to happen (still, it would be very exciting if that did turn out to
be the case).   It's always best to be prepared for the unexpected.  I
just want to know the true phylogeny, and let the chips fall where they
may.  I have some expectations, but no strong convictions, what the true
phylogenetic topology will turn out to be for the great apes.  But we
need to confirm the sister group before we can truly understand all of
the apomorphies of Family Hominidae.          
       ----------Cheers,             
                        Ken Kinman                   
***************************************************
David Campbell wrote:       
      On the specific example of human-ape comparisons, a significant
difficulty is that humans are morphologically highly apomorphic.  Our
body plans are significantly modified for upright bipedal locomotion,
whereas the apes retain a primarily climbing and knuckle-walking build.
Some help for this issue comes from a study of fossil hominids.  Exactly
what to do with highly apomorphic taxa is a more general problem in
phylogenetics, both in terms of the cladistic aversion to autapomorphies
in classification and in terms of how to deal with a shortage of
synapomorphies.