Human, chimps and evaporating evidence

[John Grehan]

As I have mentioned in earlier postings, if one simply adds the orangutan
synapomorphies to existing character data sets that purport to support a
chimpanzee/African ape connection for humans, the result is changed
considerably, to the effect that the orangutan relationship becomes the
best supported.

The other side of the issue concerns the veracity of characters proposed
for humans with chimps and gorilla in the first place. The problem with
this begins with the amazingly shoddy level of documentation for supporting
characters. I don't know if this is a feature of vertebrate systematics in
general (perhaps someone on this list could comment), but hominid
systematics is riddled with extremely poor documentation of characters and
character states from descriptions of the characters to verification of
presence or absence within ingroups and outgroups. As one who is more
acquainted with insect systematics where characters are often tediously
documented with written and pictographic illustration, the hominid
situation seems generally dreadful.

So, with this in mind I have an interest in the veracity of purported
chimpanzee/African ape synapomorphies. For the latter in particular there
seem to be a lot if one took characters at face value. Recently I went
through the set of characters proposed by David Begun (1977) who did a
study of relationships in living apes (but not humans!) and various fossil
apes. The principle relationship of interest to me is his support for an
Australopithecus-chimp clade. Begun listed 20 characters for a
chimp/gorilla/Australopithecus clade and 5 supporting a
chimp/Australopithecus clade (plus or minus a character if I miscounted) so
he gets a chimp-Australopithecus clade out of his parsimony analysis.

So I went through each one of these characters with Jeffrey Schwartz and
found that there were none that could be supported. The characters were
either invalid, or so poorly defined that they were meaningless without
further documentation. This is not just a case of my taking Schwartz's word
for it. A number of examples I could see for myself (such as the
supraorbital bar and associated channel (sulcus) that Begun says is present
in chimps and australopithecines yet is quite obviously not). Another
common problem was that Australopithecus itself is highly variable in many
of the characters Begun cited - being applicable in some species, not in
others.

I will be approaching Begun about the whole of it, particularly those that
lack sufficient definition for even another primate morphologist to
understand. However, its looking more and more like the chimp theory is a
house of cards when it comes to morphology and the relationship is more
myth than reality. For those on TAXACOM who have taken shots at me for
supporting the orangutan model I would like to see them present documented
defense of those purported human-chimp characters for which they are so
confident.

On a final note, with the chimp-human connection supposedly so absolute as
to defy refutation, one sees a remarkable state of confusion expressed even
by those who believe in it. The Scientific American article by Kate Wong is
replete with references (quoting various individuals) to this state of
mind: "researchers disagree over what makes the human lineage unique", " we
have trouble defining hominids", paleontologists can't know for certain
what those hominid traits [in those populations directly after the genetic
split between chimps and humans] were", "were going to have a lot of
trouble diagnosing the very earliest members of our clade the closer we get
to that last common ancestor"' "its really important to sort out what the
starting point was". This is the stuff of great science? This is the
quality of thinking supported by Nature and Science? Does anyone think that
the public, let alone scientists, could take human evolution seriously with
this kind of junk. Would any on this list use this kind of rhetoric and
expect anyone to take their own work seriosuly?

We will led you to confusion, but believe in us because we are right.
Fascinating!

John Grehan

Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, New York 14211-1293
Voice 716-896-5200 x372
Fax 716-897-6723
jgrehan at sciencebuff.org
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