ABSTRACT

The conceptual history of the gene, beginning as an inference from the observation of Mendelian regularities in inheritance at the turn of the last century and reaching an apex with the unraveling of its biochemical structure by Watson and Crick in 1953, figured for a long time as a standard example of successful reduction in the life sciences. This has variously led to highly reductionistic interpretations of Darwinian evolution. But ever since its internal makeup was known, the gene has also become an increasingly problematic entity. Indeed, a conceptual crisis has arisen during the last twenty years as a result of the discovery of overlapping genes, alternative splicing, and so on. What once looked like a particulate gene now turns out to be scattered across parts of the genome with no hard-and-fast boundaries. Genes seem to depend on the genome's regulatory activities which, in turn, may depend on how the molecular biologist wishes to manipulate the genome in experiment. This has led to the widespread opinion that the gene is devoid of any special reality, or, is just a word. I contest this view and continue to argue for a unified gene concept. I do so by defining the gene as the genetic underpinning of the smallest possible difference in adaptation that may be detected by natural selection. Differences in adaptation among individuals, by directing natural selection toward the genetic underpinning of such differences, may be instrumental in the formation of genes.