The Gene Concept

Gene
First published Tue Oct 26, 2004; substantive revision Tue Mar 10, 2009

“There can be little doubt,” philosopher and biochemist Lenny Moss claimed in 2003, “that the idea of ‘the gene’ has been the central organizing theme of twentieth century biology” (Moss 2003, xiii; cf. Keller 2000, 9). And yet it is clear that the science of genetics never provided one generally accepted definitionof the gene. More than a hundred years of genetic research have rather resulted in the proliferation of a variety of gene concepts, which sometimes complement, sometimes contradict each other. Some philosophers and scientists have tried to remedy this situation by reducing this variety of gene concepts, either “vertically” to a fundamental unit, or “horizontally” by subsuming them under ageneral term (for a recent example, see Gerstein et al. 2007). Others have opted for more pluralist stances. As a consequence, “the gene” has become a hot topic in philosophy of science around which questions of reduction, emergence, or supervenience of concepts and theories (along with the epistemic entities they refer to) are lively debated. So far, however, all attempts to reach a consensusregarding these questions have been unsuccessful. Today, along with the completion of the human genome sequence and the beginning of what is being called the era of postgenomics, genetics is again experiencing a time of conceptual change, voices even being raised to abandon the concept of the gene altogether in favor of new terminologies (Keller and Harel 2007). The concept of the gene, emerging out of acentury of genetic research, has been and continues to be, as Raphael Falk has reminded us not so long ago, a “concept in tension” (Falk 2000). The layout of the following article will therefore be largely historical. There exist several accounts of the historical development and diversification of the gene concept, written from the perspective of a history of ideas (Dunn 1965; Stubbe 1965;Carlson 1966, 2004; Schwartz 2008). While we will largely follow the conventional time line of events established by this literature, we will take a slightly different perspective by looking at genes as epistemic objects, i.e., as objects subjected to on-going research. This means that we will not simply relate established concepts of “the” gene, but rather analyze how changing experimental practicesand experimental systems determined and modified such concepts. After having thus established a rich historical “panorama” of the gene as a “concept in flux”, to pick up a suggestive term introduced by Yehuda Elkana (1970; cf. Falk 1986), some more general philosophical themes will be briefly addressed, for which the gene has served as a convenient “handle” in discussion. These revolve aroundthe topic of reduction, but also involve questions about causality in living systems (for fuller accounts see entries on molecular biology and molecular genetics).
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1. Prehistory of the Gene

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2. The Gene in Classical Genetics 3. The Gene in Molecular Genetics 4. The Gene in Development and Evolution 5. The Question of Reduction Bibliography Other Internet Resources RelatedEntries

1. Prehistory of the Gene
Before dealing with the historical stages of the gene concept's tangled development, we will have to see how it came into being. It was only in the nineteenth century that heredity became a major problem to be dealt with in biology (López Beltrán 2004; Müller-Wille and Rheinberger 2007). With the rise of heredity as a biological research area the question ofits material basis and of its mechanism took shape. In the second half of the nineteenth century, two alternative frameworks were proposed to deal with this question. The first one conceived of heredity as a force whose strength was accumulated over the generations, and which, as a measurable magnitude, could be subjected to statistical analysis. This concept was particularly widespread among...