284 Raphael Falk
Falk [2001b]; Schwartz [1998].)
As indicated, a crucial conceptual development was Johannsen’s distinction be-
tween genotype and phenotype [Johannsen, 1909]. At least in theory, it disjoined
the discussion of traits from the discussion of the inherited factors, or as put by
Johannsen it distinguished between the vernacular “transmission conception” and
the “genotypic conception”. The unit-character was demoted from its role of a
unit of inheritance. This worked two ways: on the one hand this segregation
allowed the handling of phenotypic variation more flexibly, rather than the Galto-
nian dichotomy of “natureversusnurture”, because the phenotype included both
a genetic and a non-genetic component. Even for traits that (phenotypically) vary
continuously, the genetic factors may vary discontinuously. This notion had been
applied when e.g., East and Nilsson-Ehle extended the Mendelian rules of inde-
pendent segregation of discrete genes to the continuous variation of “quantitative
traits” (see section 2). It was also applied to settle the dispute between Pearson’s
claim for continuous inheritance based on biometric arguments of phenotypic vari-
ation and Bateson’s on discontinuous Mendelian genotypic variation (see section
7). On the other hand, by providing non-genotypic “excuses” to the observed
phenotypic deviations, it encouraged genetic determinism. Significantly, since the
only indicator for the genotype was the phenotypic “marker”, the concept of “the
gene for” became entrenched as a major determinist notion (see, e.g., Gannett
[1999]).
Unfortunately, Johannsen’s typologist conception of the genotype, as the basic
taxonomic entity [Roll-Hansen, 1978] underpinned his deterministic view of the
genotype. When, at the same year that Johannsen published his book, Woltereck
tried to emphasize the significance of the environment and its interaction with the
genotype in regulating the patterns of individuals’ variations [Woltereck, 1909] it
was rejected. Woltereck showed that different pure-lines of Daphnia responded dif-
ferently to the same environmental effects, and that theReaktionsnorm—normof
reaction (NoR) — was specific to the specific line as well as to the specific environ-
mental factor. Conceptually, such specificReaktionsnormcurves of genotypes and
environmental conditions would make it impossible to predict the NoR from one set
of genotypes and environments to another, or put differently, genotype-phenotype
interactions were significant components of the phenotypes. Woltereck’s conclu-
sion of genotype-environmental interactions, if accepted, would have countered the
central praxis of genetics that uses phenotypic “markers” as indicators, predicting
the genotype, which was a basic tool of genetic analysis (as pointed out by Kohler
[1994] this was not a major problem with “laboratory-trained” organisms, like
Drosophila, which were cultivated under standard “environmental” conditions).
Even worse, it suggested the participation of both the genotype and the environ-
ment in determining the fitness of the individual in the process of evolution — an
explicit Lamarckian notion (Woltereck nursed Lamarckian notions, see Harwood
[1996]. As conceived by Hogben already in 1933 this “interdependence” of na-
ture and nurture argued against genetic reductionism [Hogben, 1933]. But genetic
analysis was not ripe for such claims at the time, and the genocentric position