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A Modern Unified Theory of Evolution 185
does not. The gene is never isolated and can never be selected by itself, as Mayr (e.g.,
1959f) argued in his attack on “beanbag” genetics showing that it is individuals
that really count. In general, there are 2 or 3 possible targets of selection. One is the
gametes which are directly selected. The next one is the individual and the third
one are certain types of social groups, those consisting of cooperating individuals
(e.g., in early humans).
In general, a unification of biology “was not an objective in the minds of any
of the architects of the synthesis during the 1930–1940 period. They were busy
enough straightening out their own differences and refuting the anti-Darwinians
to have time for such a far-reaching objective. It wasn’t until the 1950s that most of
the previous difficulties had been resolved that one could begin to think seriously
about the role of evolutionary biology in the whole of biology and about the
capacity of evolutionary biology to achieve a unification of the previously badly
splintered biology” (Mayr 1993a: 33; see also Smocovitis 1997: 202).
Collaboration with Th. Dobzhansky
Early in the 1930s, Mayr had given up his Lamarckian in favor of Darwinian selectionist
views (as had independently E. Stresemann and B. Rensch in Berlin)
convinced by the publications of geneticists and long conversations with James
Chapin, explorer of the Congo rainforest and his colleague at the AMNH (p. 120).
ThefirstvolumeofChapin’sBirds of the Belgian Congo (1932) was the best work on
the ecology, behavior, and biogeography of tropical birds of that time. F.M. Chapman,
the chairman of the Bird Department, still believed in direct environmental
influences and in saltation, as did Mayr’s colleagues R. C. Murphy, J. T. Zimmer,
G. K. Noble, and others. After Chapman’s retirement in 1942, Ernst Mayr became
the dominant force within the Department of Ornithology showing new theoretical
and conceptual ways to explain the development of species and other evolutionary
processes (Lanyon 1995).
Mayr’s taxonomic studies of the 1930s were written for taxonomists and did not
reveal the fact that their author was collecting data for a comprehensive evolutionary
analysis of geographic variation and speciation in birds (and other animals).
What he intended is mentioned in his second letter to Theodosius Dobzhansky
(Pasadena, California) dated 25 November 1935:
Dear Dr. Dobzhansky,
ManythanksforyourkindletterofNovember12thandforyourreprint.Iwill
send you in the next days a few of my taxonomic papers, although I doubt if
they mean much to you. I have restricted myself in the past to purely descriptive
species and genus revisions and am waiting for the completion of these
detailed taxonomic studies before I want to draw any conclusions. I am mainly
working with insular birds, which do not lend themselves as easily to the study
of gradual differences of populations as do continental birds. In fact, the majority
of the subspecific characters of these island birds are those of the type, but
could have easily originated as conspicuous gene mutations. These birds have,