Nothing New on Hennig and Rosa

[Michael Schmitt]

Dear colleagues,

since several persons asked me to respond to a recent posting of John
Grehan to this list, I do so:

At 08:57 03.07.2000 -0400, John Grehan wrote:
>A colleague kindly drew my attention to an article by Kuge and another
>person (the name is missing) published on the web page
>http://www.cladistics.org/about/hennig.html
>
The name of the second author is clearly given on this page as 'Bernd
Hennig'. Dr. Bernd Hennig (Freiburg im Breisgau, Germany) is Willi Hennig's
second son.

>The article refers to Hennig's war experience in Italy, noting that he was
>not interned, but worked in the anti-malaria service of the British. The
>author's acknowledge suggestions that during this time Hennig learned
>Rosa's theory.

This does not mean that they (or I) think this to be likely. I called Dr.
Bernd Hennig by phone and inquired about the source of the crucial passage
that his father "was not held captive in an Allied concentration camp" but
"was immediately taken into the anti-malaria service of the British
troops". It turned out that Willi Hennig had reported this to his wife in a
forces' postal service letter in May, 1945. And that's it. At the moment,
there is no more information available as to the mode of life of a German
prisoner of war taken into a British special service in 1945 in Upper
Italy. It is certain that Willi Hennig remained a POW and thus had
definitely not the freedom of moving around like a civil person, let aside
a member of the British forces.

>My current understanding of Rosa was that he was not Lamarkian, but nearer
>to the concept of orthogenesis. If this was enough to Hennig to "dismiss"
>hologenesis, still the information acquired becomes background knowledge,

There is no evidence at all that Willi Hennig had read Daniele Rosa's 1918
book. Whoever gets hold of such information should share it with us, e.g.
on this list. I admit that I have never seen this book as well. However,
Rosa published a paper in French in 1923 which he called a 'summary' of the
1918 book. I have carefully read this paper. Provided that it reflects
correctly the content of the 1918 book, it is clear that this book is
irrelevant to Willi Hennig's method of Phylogenetic Systematics. This was
already reported by Carmine Colacino on 13.05.1999 to this list as a
message from Chris Humphries, London:
>> Having read Rosa's
>> original book (sadly the Natural History Museum in London only possesses a
>> xerox copy I made in Bologna some years ago) I can only conclude that
>> Croizat's claim that somehow Rosa pre-empted Hennig is fanciful at best.
>> Rosa had a point but he did undertake the task that Hennig set for himself.
>> Rosa did not flesh out an argumentation method for understanding which
parts
>> of morphology that might be construed as synapomorphy, and he did not
>> provide a method for determining relationships in terms of evolution by
>> common descent.  He did not break similarity into three different kinds
>> (monophyly, paraphyly and polyphyly) as Hennig did, and he certainly did
not
>> take on the typologists as Hennig (with Zimmerman) did in the late 1930s.
>> Croizat tried to make Rosa into some great hero to suit his own "Futurist"
>> ends.  Croizat neither understood Phylogenetic Systematics nor what Hennig
>> really stood for.  As with all great ideas that emerge from some milieu of
>> the time someone who clarified the position will inevitably be given the
>> credit.

I can only add that, according to the 1923 summary, there are two points in
Rosa's ideas superficially resembling aspects of Hennig's method:
1) Rosa stated that there is a 'law of ramification' that causes species
obligatorily to split into two daughter species. Hennigian cladograms are
normally designed dichotomous. However, Hennig explicitely discussed the
mode of speciation without starting from dichotomous splitting. On the
contrary, in his 1966 book he states explicitely that "if phylogenetic
systematics starts out from a dichotomous differentiation of the
phylogenetic tree, this is primarily no more than a methodological
principle" (p. 210).
2) Rosa was of the opinion that of the two descendant lineages always one
will cange evolutionarily at a higher rate than the other. He called the
faster changing line "linea precoce" (precocious), the slower changing one
"linea tardiva" (tardy). The precocious line should on one hand evolve at a
higher rate, but on the other hand keep an inferior organization than the
tardy line. I could not find a theoretically convincing substantiation for
this statement. My impression is that Rosa stated these relations
axiomaticly. It is certainly important that Rosa did not provide any
empirical criterion as to how to distinguish between the precocious and the
tardy line, nor did he even intimate that his "theory" would offer a
practical tool for systematics. Here, one could see a parallel to Hennig's
conceptions of apomorph and plesiomorph. However, Hennig referred not at
all to a 'law of different evolutionary speed'. From p. 88 in his 1966 book
it becomes clear that he regarded character transformation as a
prerequisite for systematists in order to distinguish different species: if
we can recognize two (or more) species where before was only one, then at
least one character must have changed in each additional lineage. And this
is all, there is no idea of an obligatorily faster evolving lineage
whatsoever.

Since Willi Hennig from his 1950 book on conscientiously cited other
sources that contributed to his method (e.g. Adolf Naef's papers), it is
pure speculation to insinuate that he had knowledge of Rosa's 'theory' but
dismissed it.

>and if incorporated (which is evidently the case if a historical connection
>is established) cladists will owe as much historical debt to Rosa as to
>Hennig. Perhaps the society will have to be renamed the Willi Hennig and
>Daniele Rosa society!
>

Ceterum censeo provocationem esse ignorandam.

                                        Greetings
                                    Michael Schmitt



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