[Taxacom] New synapomorphy for humans and orangutans

John Grehan jgrehan at sciencebuff.org
Mon Jan 4 12:00:59 CST 2010


> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Richard Zander
> 
> The orangutan problem is Taxacom's very own instructive puzzle, with
> equivocal signs of what the ancestor of man might be like in expressed
> traits. Suppose both chimp and gorilla were extinct and unknown from
> fossils. Well, the shared ancestor would be taken to be some
intermediate
> between orang and man. What if there were a dozen chimp and
gorilla-like
> lineages between man and orangutan? Well, the immediate ancestor would
be
> something like a chimp or gorilla.

Sure - IF that were the case. But the fossil and living morphological
evidence suggests otherwise.

> I note that John Grehan has fallen into the "evolutionary
relationships =
> evolution" fallacy. This is easy to do because of peer pressure.

Gee wiz

> Relationships are okay, but indirect. We really want to know what the
> sequential evolutionary derivation of taxa might be, which is direct.
I
> think we can infer the latter in many cases, e.g. when a number of
> exemplars of the same species bunch together on a cladogram, well the
> ancestral taxon is that species. Yet those who insist that
relationships
> are the end-all of evolutionary analysis will not follow the several
clear
> lines of investigation that follow this observation, e.g. the
ancestral
> taxon of an autophyletic taxon is the paraphyletic taxon generating
it.

Maybe. Maybe not. One can get a headache out of this stuff sometimes.
But regardless of such theoretical conundrums the morphological evidence
suggests humans are more closely related to orangutans than African
apes. Whether the process is by some kind of paraphyly, coincidence,
parallelism etc remains to be seen.

John Grehan

> 
> _______________________
> Richard H. Zander
> Missouri Botanical Garden
> PO Box 299
> St. Louis, MO 63166 U.S.A.
> richard.zander at mobot.org
> 
> 
> ________________________________
> 
> From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Kenneth Kinman
> Sent: Sat 1/2/2010 8:11 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] New synapomorphy for humans and orangutans
> 
> 
> 
> Oh dear,
>       It's deja vu all over again.  But now all you need to do is to
> find a genome change which backs it up (or any of your other proposed
> synapomorphies).  Otherwise, it's most likely just what the authors
> suggested it is---homoplastic, not synapomorphic.
>                  -----Ken
> P.S.  It would be interesting to know if bonobo chimps have a later
> eruption of molars than regular chimps.  Wouldn't be at all surprised
if
> bonobos erupt closer to 4.6 years than regular chimps at 4.0 years.
> With so little sampling, I wouldn't read too much into this character
> anyway.  Declaring it a synapomorphy is at best premature.
> 
> 
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