Darwin-L Message Log 8:6 (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.

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<8:6>From DARWIN@iris.uncg.edu  Mon Apr  4 21:27:22 1994

Date: Mon, 04 Apr 1994 23:27:14 -0500 (EST)
From: DARWIN@iris.uncg.edu
Subject: Re: cladistics & distance data
To: darwin-l@ukanaix.cc.ukans.edu

Rick Toomey's and Kim Sterelny's comments on the original question "What
makes a technique cladistic?" have given me pause, and I'm starting to step
back from my original answer.  I had said that intention is what makes a
technique cladistic, rather than the particular type of data used, etc.
Let's see what I can make of the question now.

First I take it that we are agreed on Paul DeBenedictis's first question,
that distance data can be used to estimate phylogeny.  In any particular
case it may be a good way or a bad way to estimate phylogeny, but it is a
way.

The question at issue is his other one: "What makes a technique cladistic?"
This of course is a matter of definition, but it is interesting to consider
nonetheless. (Note clever deployment of classic rhetorical strategy: "OK,
so maybe I am wrong, but it doesn't really matter that much anyway.")  ;-)

One thing I failed to do in my original answer was distinguish between
present-day prescription and historical description (shame on me), and that
is what Rick and Kim both picked up on.  Paul had asked his question in the
specific context of a review of a modern work, and I was trying to make the
point that it didn't really matter whether the author was using distance
data or character data: what he was trying to do was make trees, and hence
he was doing something cladistic.

Rick and Kim point out that there were people making trees ever since the
_Origin_ and that it doesn't seem right to say that they were all doing
cladistics.  There certainly were, and no, it doesn't seem right to call
their work cladistic.  I find myself wanting to distinguish between
"phylogeneitc" and "cladistic" now, however.  Many systematists since the
late 19th century have tried to reconstruct phylogeny.  (As Kim points out,
though, they often had other interests mixed in with that activity in a
somewhat confused manner from the modern standpoint.)  If I say that
"cladistic analysis" is a particular method of reconstructing phylogeny,
then maybe Rick and Kim will be satisfied -- it would be that method of
reconstructing phylogeny which is based on the idea that only innovations
(derived character states) can be used to identify clades, and that a
"character" is a difference among taxa from which we infer an evolutionary
event, the states of the character being the different "sides" of the event
(before and after).

Under this definition, "cladistics" is reduced to more or less traditional
(Hennigian) character-based studies of the sort that really didn't exist
much before the 1950s or '60s.  But the enterprise of (non-cladistic)
phylogenetic reconstruction goes back much farther.  Modern distance methods
of phylogenetic reconstruction would thus be "phylogenetic" but not
"cladistic".  (For our next lesson I will explain the difference between
"tomato" and "tomato".)

I'm sure the eyes of all the non-systematists are starting to glaze over at
this point.  These disputes about shades of meaning of technical terms can
look very odd from the outside, I know.  This discussion is a bit like the
discussion we were having a while ago on the word "structuralism", though.
In linguistics we might ask what makes a technique "structuralist" (as I did
a while ago, and Sally Thomason replied very helpfully), or "typological" or
"historical".  "Typology" is another word that is used in both linguistics
and systematics; in linguistics it is a legitimate mode of inquiry (so I
understand), but in systematics "typology" usually considered a term of
abuse ("he is a typologist" is kind of like saying "he is a communist").

An excellent book came out a couple years ago: _Keywords in Evolutionary
Biology_, edited by Evelyn Fox Keller and Elisabeth Lloyd (Cambridge:
Harvard University Press).  It is a collection of chapters devoted to terms
like "selection", "fitness", species", etc.  Glancing at my copy I see
chapters by _four_ Darwin-L members: Richard Burian on "Adaptation", Robert
Brandon on "Environment", Michael Donoghue on "Homology", and Peter Stevens
on "Species".  (We are in very good company here.)  Perhaps an expanded
version of the book or another similar collection of chapters could be made
that would extend beyond evolutionary biology to key terms used in all the
historical sciences.

Bob O'Hara, Darwin-L list owner

Robert J. O'Hara (darwin@iris.uncg.edu)
Center for Critical Inquiry and Department of Biology
100 Foust Building, University of North Carolina at Greensboro
Greensboro, North Carolina 27412 U.S.A.

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