Genetics was established on a strict particulate conception of heredity. Genetic linkage, the deviation from independent segregation of Mendelian factors, was conceived as a function of the material allocation of the factors to the chromosomes, rather than to the multiple effects (pleiotropy) of discrete factors. Although linkage maps were abstractions they provided strong support for the chromosomal theory of inheritance. Direct Cytogenetic evidence was scarce until X-ray induced major chromosomal rearrangements allowed direct correlation of genetic and cytological rearrangements. Only with (...) the discovery of the polytenic giant chromosomes in Drosophila larvae in the 1930s were the virtual maps backed up by physical maps of the genetic loci. Genetic linkage became a pivotal experimental tool for the examination of the integration of genetic functions in development and in evolution. Genetic mapping has remained a hallmark of genetic analysis. The location of genes in DNA is a modern extension of the notion of genetic linkage. (shrink)

This article discusses the work of George Udny Yule in relation to the evolutionary synthesis and the biometric-Mendelian debate. It has generally been claimed that (i.) in 1902, Yule put forth the first account showing that the competing biometric and Mendelian programs could be synthesized. Furthermore, (ii.) the scientific figures who should have been most interested in this thesis (the biometricians W. F. Raphael Weldon and Karl Pearson, and the Mendelian William Bateson) were too blinded by personal animosity towards each (...) other to appreciate Yule's proposal. This essay provides a detailed account of (i.), maintaining that Yule's 1902 proposal is better understood as a reduction, not a synthesis of the two programs. The results of this analysis are then used to evaluate (ii.), where I will instead argue that Bateson and the biometricians had good reasons to avoid endorsing Yule's account. (shrink)

The historian Raphael Falk has described the gene as a ‘concept in tension’ (Falk 2000) – an idea pulled this way and that by the differing demands of different kinds of biological work. Several authors have suggested that in the light of contemporary molecular biology ‘gene’ is no more than a handy term which acquires a specific meaning only in a specific scientific context in which it occurs. Hence the best way to answer the question ‘what is a gene’, and (...) the only way to provide a truly philosophical answer to that question is to outline the diversity of conceptions of the gene and the reasons for this diversity. In this essay we draw on the extensive literature in the history of biology to explain how the concept has changed over time in response to the changing demands of the biosciences . Finally, we outline some of the conceptions of the gene current today. The seeds of change are implicit in many of those current conceptions and the future of the gene concept looks set to be at as turbulent as the past. (shrink)

In 1941/42 Konrad Lorenz suggested that Kant's transcendental categories ofa priori knowledge could be given an empirical interpretation in Darwinian material evolutionary terms: a priori propositional knowledge was an organ subject to natural selection for adaptation to its specific environments. D. Campbell extended the conception, and termed evolution a process of knowledge. The philosophical problem of what knowledge is became a descriptive one of how knowledge developed, the normative semantic questions have been sidestepped, as if the descriptive insights would automatically (...) resolve them. This came at a time when the traditional concept of knowledge as universally true, justified beliefs had been challenged by subjectivist, intercommunicative coherence frameworks. Much of the literature on evolutionary epistemology claimed that knowledge in general, and science as its epitome in particular, evolved along lines analogous to organic biological evolution. I refer here only to the view of knowledge as an extension of material biological evolution. These theories of evolutionary epistemology, contrary to the relativist notions of naturalized epistemology, adopted strict realist positions.Although there is no contention with the claim that biological evolution provided the raw material and the constraints for human knowledge, cognition is not knowledge and knowledge is not constrained by it beyond some trivial truisms. The view that sees evolution as a knowledge/cognition process is coercing a loosely defined term into the status of a phenotypic trait on which selection could act. This disregards the intricate many-to-many relationship between correlates of knowledge and biological capacities. But even if we grant the correlates of knowledge the status of selectable traits, the heritability of alternative phenotypes would be low and unpredictable due to the high, open-ended environmental malleability of such complex characters in the course of development. Such concepts are therefore biologically inconsequential. (shrink)

This paper discusses the individuation of characters for the use asunits by geneticists at the beginning of the 20th century. Thediscussion involves the Presence and Absence Hypothesis as a case study. It issuggested that the gap between conceptual consideration and etiological factorsof individuating of characters is being handled by way of mutual adjustment.Confrontation of a suggested morphological unit character with experimentresults molded the final boundaries of it.