Ornithology, Evolution, and Philosophy 123

12 Summary: Appreciation of Ernst Mayr’s Science 377
Massachusetts. During the following years he discussed the role of species in
nature, sibling species, isolating mechanisms, the process of speciation, the interaction
of genes and their varying selective values, the unity of the genotype, the
two-step nature of natural selection (accident and design) thus establishing evolutionary
biology as a separate field of enquiry in the United States. As spokesman of
systematics and evolutionary biology Mayr emphasized the division of biology into
functional biology analyzing proximate causations and organismic-evolutionary
biology studying ultimate causations. A balanced biology advances both fronts,
that of molecular biology and physiology as well as that of organismic-systematicevolutionary
biology. In his books on Animal Species and Evolution (1963b) and
Populations, Species and Evolution (1970e) Mayr united systematics, population genetics
and evolutionary biology, but he never discussed in any detail or conducted
functional-physiological studies himself.
From the late 1950s, and especially after his “retirement” as Professor of Zoology
in 1975, Mayr turned increasingly to studies of the history and philosophy of
biology publishing numerous works, particularly on Charles Darwin and his five
theses of evolution (instead of one), and a large book on the conceptual history
of biology (1982d). Already in 1949 he had written to Erwin Stresemann: “It is
important to emphasize the evolutionary angle as a counterbalance against the assertions
of the physicists and chemists who see nothing in this branch of research”
(25 January 1949). Mayr discussed the many peculiarities of life such as historical
contingency, genetic programs, diversity, individuality, classification, and others
which necessitate a modern philosophy of biology excluding essentialism, physicalist
reductionism, finalism, and determinism. He emphasized the distinctness
(autonomy) of biology as a science from physics and forged a third synthesis connecting
systematic biology, evolutionary biology, and the history and philosophy
of biology in his recent books Toward a New Philosophy of Biology (1988e), One
Long Argument. Charles Darwin and the Genesis of Modern Evolutionary Thought
(1991g), This is Biology (1997b), and What Makes Biology Unique? (2004a).
We look back: In ornithology and the new systematics, Mayr was a student of
Erwin Stresemann whose insights (and those of B. Rensch) he extended over the
entire field of zoology and appreciably enlarged through the inclusion of population
genetics. As a lifelong naturalist, Ernst Mayr was always interested in the diversity
of the living world, its origin and biological meaning as well as in the clarification
of evolutionary concepts and processes. Although he was not the originator of the
biological species concept, he formulated its familiar definition which was widely
adopted and he placed the biospecies concept at the center of the synthetic theory
of evolution. As a torch bearer of Darwinism he decisively influenced the field of
evolutionary biology as well as those of the history and philosophy of biology.
He always read very widely and was interested not only in facts but also in the
underlying theories and principles. He was a very hard worker, as shown when he
finished his PhD dissertation and the necessary courses in 16 months and when,
as director of the MCZ, he often got up at 4:30 a.m. to work on his manuscripts.
His excellent memory was a great help in recalling information whenever needed.
The breadth of his biological knowledge and interests enabled him to forge several