Turning around

[John Grehan]

I don't have any 'proven' solution to the DNA base and morphology
contradiction.

 

There is at least reason to argue that the DNA sequence stuff is
phenetics rather than cladistics and so is as potentially misleading as
overall similarity of morphology (which also connects humans with
African apes).

 

When it comes to systematists I am hardly preaching to the choir. Most
systematists seem to believe that DNA sequences overrule contradictory
morphology. 

 

John Grehan

 

________________________________

From: Richard.Zander at mobot.org [mailto:Richard.Zander at mobot.org] 
Sent: Wednesday, February 22, 2006 12:11 PM
To: John Grehan; TAXACOM at LISTSERV.NHM.KU.EDU
Subject: RE: Re: [TAXACOM] Turning around

 

Well, John . . . 

Statistics is based on a phenomenon in physics called the binomial
distribution. It is not imaginary or supportive of empty explanations.
In speculative phylogenetics, scientific data (facts, or well-documented
observations) plus a scientific model yields (with a particular method)
a scientific hypothesis. Of course, the Bayesian one-time retrodiction
of a historical event is fraught with problems, but it is still
scientific. Based on sequence facts and a model generated from facts, it
does give you a theory that is a scientific approach to scientific
truth, in the sense that if there is no argument against, and plenty of
statistical support (in terms of
not-to-be-expected-from-random-generation of data) for, then one can
base one's conduct (further research) and bet one's science on the
hypothesis. The scientific results are not empty explanations by
armchair scholars, but are actual guides to conduct (or you can reject
them if you think technique, model or data are not up to snuff, but then
you should have an idea of exactly why not). Another guide to conduct is
in the artistic or spiritual realm, involving the apprehension of Truths
that powerfully affect the psyche. If you have a third Guide, let us
know.

What happens when strongly supported morphological results contradict
strongly supported molecular results? One can come up with a hypothesis
to test, like I did for the situation with orang-homo-pan.
Contradictions are not always a sign of faulty data or model or method,
they may be a clue to new processes to be discovered or further
investigated.

Some philosopher wrote that often if you can state the problem clearly
enough, the answer is obvious). If the problem is that there is too much
focus on molecular analyses while ignoring morphological analyses, you
are preaching to the choir. If you have a new way of combining the two
without just throwing out the molecular end, let us know. 

______________________ 
Richard H. Zander 
Bryology Group, Missouri Botanical Garden 
PO Box 299, St. Louis, MO 63166-0299 USA 
richard.zander at mobot.org <mailto:richard.zander at mobot.org> 
Voice: 314-577-5180;  Fax: 314-577-0828 
Websites 
Bryophyte Volumes of Flora of North America: 
http://www.mobot.org/plantscience/bfna/bfnamenu.htm 
Res Botanica: 
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Shipping address for UPS, etc.: 
Missouri Botanical Garden 
4344 Shaw Blvd. 
St. Louis, MO 63110 USA 

-----Original Message----- 
From: John Grehan [mailto:jgrehan at sciencebuff.org] 
Sent: Wednesday, February 22, 2006 7:58 AM 
To: Richard Zander; TAXACOM at LISTSERV.NHM.KU.EDU 
Subject: RE: Re: [TAXACOM] Turning around 

Tindall has already indicated the complexity of questions about DNA and
morphology. As for molecular traits accumulating with each speciation
event the "logic is great" which is another way of saying that it is an
assumption. Assuming the assumption is correct, it is another step to
saying that the accumulation of changes will actually correlate in some
necessary way with the phylogenetic sequence. 

As for statistical support, any measure of overall similarity might be
statistically sound without it necessarily being any more accurate about
the phylogenetic sequence if there is no a priori exclusion of
plesiomorphic states. With bases potentially flipping between one or
other base alternatives, and that base alternative (or even loss or

gain) providing no indication of what came before, it all seems to come
down to statistical imagination of what is inherently untestable
(Probably sticking my neck out on that one). Of course one can invoke
any number of statistical and theoretical models to accommodate this
problem - which is what molecular theorist do.

And then here is the problem of apples and oranges (not orangs). What if
a statistically well supported morphology contradicts a statistically
well supported sequence pattern? I suppose some would say that the DNA
is always better because one can always have more characters (what seems
to me to be another kind of phenetic argument [phenetic as in overall
similarity]). Then there are others who say combine the data as if
apples were oranges.

As for the assertion that "morphology does seem to show a set of ancient
orangutan genes reactivated in homo in selective response to particular
environmental conditions" that is factually incorrect. It's just an ad
hoc hypothesis to protect DNA models from falsification [actually its
interesting that this popped up because one prominent hominoid
systematist has more or less admitted to me that the morphological
support for humans and African apes [let along chimpanzees which is
pretty well non existent] is far less than support for the human and
orangutan and so has come up with the very same assertion. Anything to
protect the deification of DNA bases.

"As an explanation, it works, but proof is so far lacking". Any
explanation works in some way or other according to the purposes of the
author.

Successful historical predictions about past tectonic events based on
the phylogenetic classification of plants and animals shows that these
classifications do reflect something of a "true" phylogeny at least to
the point of being able to successfully predict something of the real
world. So perhaps one is not wasting time over the question of the
"true" phylogeny. 

The great thing about the orangutan is that the issue of human origin is
so prominent and so it raises the profile of an issue over morphology
and genetics that is otherwise generally buried or conveniently ignored
(or there is propaganda about a dialogue between genetics and morphology
as in Science). The real question (in my mind) is whether the 'science'

of systematics can acknowledge this scientific problem and rather than
suppressing it (as through editorial politics), encourage the
dissemination of both the evidence and the different theoretical
perspectives. Primatologists, for example, apply the principle of
mediocrity by taking the position that the suppression of Schwartz's
theory is justified simply because it has been suppressed by everyone
(i.e. if it were any good it would not have been suppressed). 

Perhaps primatology has yet to experience the Renaissance. 

John Grehan