Philosophy of Biology

74 Sahotra Sarkar

However, the critique of theoretical population genetics that became most influ-
ential in the 1960’s, and continues to be influential today, was due to Mayr. Mayr
had read Waddington’s critical remarks after they were republished inThe Strat-
egy of the Genesin 1957, and had agreed with them.^34 At the 1955 Cold Spring
Harbor symposium at which Dobzhansky had delivered his ringing endorsement of
theoretical population genetics, Mayr had distinguished between the approaches
of the mathematical population biologists and “field naturalists”. But, in sharp
contrast to Sheppard’s 1954 assessment, for Mayr, the field naturalists were not
simply providing data for the theorists. Rather, they were supposed to be have
a different and more sophisticated, though not entirely satisfactory, view of the
evolutionary process. Mayr elaborated on this point: what was wrong with the
mathematical population geneticists was that their analysis was limited to “sim-
ple Mendelian characters or simple frequencies of genes in natural populations”
whereas what was required was the consideration of “entire genetic complexes”
(p. 327). The field naturalists were also at fault for not sufficiently integrating
genetics into their work. However, according to Mayr, what was needed was phys-
iological genetics, rather than mathematical population genetics. Mayr did not
directly criticize Fisher, Haldane and Wright. Rather, he did not mention them
and, instead, endorsed the work of Dobzhansky, King, Thoday, Wallace and others
as being the most relevant to the creation of a “new population genetics” which
incorporated the “integration of genotypes” (p. 332). The result, he grandiosely
claimed, was “a theory of relativity in the field of population genetics” (p. 333).
Presumably, Mayr’s self-acknowledged inability to follow the mathematical work
of Fisher, Haldane and Wright’s models had prevented him from being more critical
in 1955. Waddington, however, was reputed to have the necessary mathematical
skills. In 1959 Mayr, emboldened by Waddington’s remarks, presented his crit-
icisms of the mathematical population geneticists more directly. That year, the
Cold Spring Harbor Symposium on Quantitative Biology was devoted to “Genet-
ics and Twentieth Century Darwinism” to mark the centenary of the publication
of Darwin’s Origin. Mayr, in a provocative address, “Where Are We?”, fully
challenged the orthodox view of the role of theoretical population genetics in evo-
lutionary theory.
Mayr distinguished three periods in the history of evolutionary genetics:

(i) a “Mendelian” period from 1900 to 1920 allegedly dominated by the view

that evolution took place through mutations;

(ii) a period of “classical population genetics”, from 1920 to the late 1930’s,

during which the

emphasis... was on the frequency of the genes and on the control

of this frequency by mutation, selection, and random events. Each

gene was essentially treated as an independent unit favored or

discriminated against by various causal factors. In order to permit

(^34) Ernst Mayr (personal communication).