Haldane and the Emergence of Modern Evolutionary Theory 75mathematical treatment, numerous simplifying assumptions had
to be made, such as that of an absolute selective value of a given
gene. The great contribution of this period was that it restored the
prestige of natural selection... and that it prepared the ground for
a treatment of quantitative characters. Yet, this period was one
of gross oversimplification. Evolutionary change was essentially
presented as an input or output of genes, as the adding of certain
beans to a beanbag and the withdrawing of others. (p. 2)“Beanbag genetics”, according to him, had outlived its utility and had to be
replaced by(iii) the “newer population genetics”, starting in the late 1930’s, and “character-
ized by an increasing emphasis on the interaction of genes” (p. 2), leading
to the “theory of relativity” that he had pompously announced in 1955.The period of beanbag genetics, according to Mayr, had been dominated by the
“mathematical analyses and models” of Fisher, Haldane and Wright. Mayr put his
challenge to them bluntly: “These authors, although sometimes disagreeing with
each other in detail or emphasis, have worked out an impressive mathematical
theory of genetical variation and evolutionary change. But what, precisely, has
been the contribution of this school to evolutionary theory, if I may be permitted
to ask such a provocative question?” (p. 2). Explicitly endorsing Waddington’s
[1957] criticisms, Mayr attempted to provide his answer:
It seems to me that the main importance of the mathematical the-
ory was that it gave mathematical rigor to qualitative statements long
previously made. It was important to realize and to demonstrate math-
ematically how slight a selective advantage could lead to the spread of
a gene in a population. Perhaps the main service of the mathemati-
cal theory was that in a subtle way it changed the mode of thinking
about genetic factors and genetic events in evolution without necessar-
ily making any startlingly novel contributions. (p. 2)Mayr concluded: “I should perhaps leave it to Fisher, Wright, and Haldane to
point out themselves what they consider to be their major contributions” (p. 2).
Fisher, who died in 1962, never responded to Mayr’s remarks. However, Wright’s
response was immediate. Wright was present at Cold Spring Harbor for the 1959
symposium though he did not present a paper. However, when asked to review
the proceedings for theAmerican Journal of Human Genetics, Wright only listed
the other papers in the volume while devoting the entire review to an analysis of
Mayr’s contentions.^35 He challenged Mayr’s interpretation of the history of ge-
netics. Between 1900 and 1920, he pointed out, that many geneticists had been
(^35) For more detail, see Provine [1986, 481–484].