Australopithecus and orangutans

[Jason de Koning]

> I already have.

No you have not.  You have declared from principle that all molecular
characters are invalid as a source of information on common ancestry,
regardless of what you do with them.  That does not qualify as "direct
appraisal" in my mind.

Assuming that you admit that any principle used to guide inquiry or
interpretation can (and should) be subject to testing, here is a test
of your logic:  if molecular characters can never be used for
evolutionary analysis, then why do they so frequently give phylogenies
that are congruent with "real cladistic analyses"?  Are you really
saying that morphological and molecular trees never agree (or agree as
or less often than expected by chance)?  If not, then you have accepted
that molecular analyses reveal some historical information.  At this
point, I suggest you ask yourself HOW can this be?

My point is that instead of dogmatically dismissing all molecular
characters, you might consider actually analysing them--in whatever way
tickles you--and seeing what they have to say.  Maybe it would give you
a better appreciation for their value.   ...that is what I consider
"direct appraisal".

> The difference is that the morphological synapomorphies can each be
> treated on their own merits whereas the molecular characters are an
> unknown mix of apomorphic and plesiomorphic states. In Ken's case he
> is positing one set of synapomorphies (human-chimp) over another
> (human-orangutan).

No, i don't think so.  The process of considering molecular characters
can be done in exactly the same way as with morphological characters.
What is the difference between A versus T and tail versus no tail (as a
discrete character)??   The only difference is in how you treat the
characters, and there is no restriction on this, whatsoever...

- Jason



On Wednesday, May 14, 2003, at 12:39  PM, John Grehan wrote:

> At 09:46 AM 5/14/2003 -0400, Jason de Koning wrote:
>>> ...(and one's skepticism should be based on some kind of direct
>>> appraisal of the characters)...
>>
>>> the total number of proposed human-orangutan synapomorphies
>>> currently stands at 36 (and some may be more robust than others).
>>
>> Well since that's how you feel, the total number of molecular
>> synapomorphies supporting ((human, chimp) orang) is probably around
>> 3-5 orders of magnitude beyond that figure at the moment.  Do you yet
>> care to confront your skepticism and "directly appraise" those
>> characters?
>
> I already have. I have commented earlier (if memory serves me
> correctly) that molecular 'synapomorphies' are not determined prior to
> analysis, but are inferred after parsimony or maximum likelihood
> methods that impute a derived status to characters. To me that's just
> applying tree construction techniques to characters that are an
> unknown combination of plesiomorphic and apomorphic states and the
> shortest resulting tree infers those characters to be the
> synapomorphies.
>
> In Ken's case I don't think he has identified the nature of his
> skepticism. Perhaps its based on molecular characters, perhaps on
> morphological. Perhaps he could offer clarification on that.
>
> John Grehan
>
>
>> - Jason
>>
>> </blockquote></x-html>
>
> Dr. John Grehan
> Director of Science and Collections
> Buffalo Museum of Science
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> jgrehan at sciencebuff.org
> http://www.sciencebuff.org/biogeography/Panbiogeography/
> Panbiogeography-Gate.htm
> http://www.sciencebuff.org/HepialidaeGate.htm
>