Ornithology, Evolution, and Philosophy 123

A Modern Unified Theory of Evolution 199
15 years and that I had read voluminously. Even though I did not maintain a ‘Notebook
on Transmutation of Species,’ as Darwin did, I nevertheless had kept massive
excerpts from the literature always with comments of my own. Unfortunately all
this has now disappeared; I probably threw it out when I moved from New York to
Cambridge.
What is also evident to a careful student is that in various major issues I tended
to diverge from both Simpson and Dobzhansky, as much as all three of us stood on
the common ground of the Evolutionary Synthesis. My emphasis on populations
and horizontal evolution is altogether absent in Simpson. My emphasis on the
essential completion of the building-up of isolating mechanisms during geographical
isolation is not shared by Dobzhansky. And there are various other differences.
Even though I still express one or two reservations concerning the power of natural
selection, I nevertheless was a far more consistent selectionist than Dobzhansky,
who had been strongly influenced in his thinking by Sewall Wright.”
The New Systematics
E. Stresemann and B. Rensch, Mayr’s mentors at the Museum of Natural History
of Berlin, pursued their work as biologists rather than as species cataloguers. Systematics
had become in their hands truly a branch of evolutionary biology. Other
scientific staff members in Berlin were also excellent. Three of the entomologists
more or less acknowledged and practiced new systematics: W. A. Ramme, worked
on orthopterans and introduced Mayr to the concept of sibling species; E. M. Hering,
with butterflies and mining insects, and H. Bischoff, who prepared a major
book on the biology of hymenoptera. None of them was just an alpha taxonomist.
When Mayr came to the United States, he was appalled at the typological spirit
dominating taxonomy. Each species was thought to have an essential nature, and
species were defined by their degree of difference from one another (Mayr 1999k:
XIX). He therefore decided to include in his book (1942e) a complete presentation
of the European approach, one whose spirit Julian Huxley (1940) had captured in
the phrase “new systematics” (although that book itself contained very little of this
new approach). Mayr’s book (1942e) consists of two parts, (1) an introduction to
the new systematics and (2) an analysis of species and speciation. Providing the first
comprehensive treatment, after Rensch (1929, 1934), of modern systematics at the
species level in English, Systematics and the Origin of Species became highly popular
among taxonomists. Whereas the English-American literature made not much
of a contribution to the evolutionary synthesis, central European and also Scandinavian
systematics contributed massively to the synthesis by stress on population
thinking, the biological nature of species, the study of geographical variation, and
the clear understanding of geographical speciation in a wide variety of animals
(besides birds also in mammals, reptiles, amphibians, fish as well as invertebrates).
One of Mayr’s major achievements was to summarize and synthesize this scattered
European literature which, for linguistic reasons, had remained unknown internationally.
Among a total of 450 references, the bibliography includes 174 European,