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Darwin-L Message Log 8:2 (April 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.


<8:2>From toomey@denr1.igis.uiuc.edu  Fri Apr  1 07:48:41 1994

Date: Fri, 1 Apr 1994 07:48:27 -0600
From: Rick Toomey <toomey@denr1.igis.uiuc.edu>
To: darwin-l@ukanaix.cc.ukans.edu
Subject: Re: cladistics & distance data

In answer to Paul DeBenedictis question:

"What makes a technique cladistic?"

Robert J. O'Hara (darwin@iris.uncg.edu) answered

> have come around to the view that Greg Mayer has expressed here once or
>twice (he taught me everything I know), that we should take the terms
>"cladistic" and "phenetic" to refer to intentions rather than particular
>procedures, types of data, or algorithms.  A technique is cladistic if it is
>used for the purpose of estimating phylogeny.  Sibley's intention in his DNA
>hybridization work is clearly to estimate phylogeny, and so he is using
>distance data in a cladistic manner.  Now whether the phylogenetic estimates
>he produces are good ones is a separate issue.  I have been critical of them
>here before.  But the fact that they may be poor estimates in some cases
>does not, in my view, make them non-cladistic.

I am going to have to respectfully disagree.  If intentions are all that is
required for a technique to be cladistic, then much of the post
acceptance of Darwin (Charles, that is) systematic work is cladistic.
At least this would be the case in vertebrate paleontology (my field).
The goal and purpose of much of the research has been to reconstruct
the phylogeny of organisms.  However, I would be hard-pressed to
describe the gestalt based hypotheses of relationships popular in the
nineteenth and early twentieth century as cladistic.  (This is not to
say that the proposed relationships were necessarily incorrect, only
that the basis for the phylogenies were not explicitly stated.)

Instead, I would say that cladistic refers to a procedure rather than an
intention.  I think that there is a feature necessary and sufficient for a
method to be considered cladistic (the synapomorphy of cladistic
methods, if you will).  This feature is that cladistic methods must make
an explicit evaluation of whether features shared by organisms are
uniquely shared or part of a primitive suite of features.  In jargon -- the
explicit rejection of plesiomorphic characters in the evaluation
of phylogeny.

While I'm at it I should probably introduce myself.  I am a
vertebrate paleontologist at the Illinois State Museum.  I work
as a post-doctoral research associate studying the changes in
small mammal faunas over the last 200,000 years and what these
changes tell us about changing environmental and climatic conditions.

Rickard S. Toomey   Illinois State Museum
toomey@denr1.igis.uiuc.edu

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