Hennig & the parsimony criterion

Kirk Fitzhugh kfitzhug at nhm.org
Wed Aug 1 19:46:28 EST 2001


During the "Polychaete and Cladistics" course in Iceland after the 
Polychaete Conference, one of the students asked me if Hennig (1966) 
explicitly stated or used the concept of parsimony, and I said I'd send him 
the page reference. Unfortunately, I don't recall who asked me this 
question, so I thought I'd throw this out in the hopes that the answer gets 
to the intended person.

The only reference to the use of parsimony I have seen is in the form of 
what Hennig called his "auxiliary principle," although he never used the 
word "parsimony" in his book. The relevant passage from Hennig (1966: 121) 
is as follows:

"I have therefore called it an 'auxiliary principle' that the presence of 
apomorphous characters in different species 'is always reason for 
suspecting kinship [i.e., that the species belong to a monophyletic group], 
and that their origin by convergence should not be assumed a priori' 
(Hennig, 1953). This was based on the conviction that 'phylogenetic 
systematics would lose all the ground on which it stands' if the presence 
of apomorphous characters in different species were considered first of all 
as convergences (or parallelisms), with proof to the contrary required in 
each case. Rather the burden of proof must be placed on the contention that 
'in individual cases the possession of common apomorphous characters may be 
based only on convergence (or parallelism).'"

Best wishes,
Kirk

------------------------------------------

FELIX QUI POTUIT RERUM COGNOSCERE CAUSAS.

------------------------------------------
Kirk Fitzhugh, Ph.D.
Associate Curator of Polychaetes
Research & Collections Branch
Los Angeles County Museum of Natural History
900 Exposition Blvd
Los Angeles CA 90007
Phone:   213-763-3233
FAX:     213-746-2999
e-mail:  kfitzhug at nhm.org
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