The Bithorax Complex: The First Fifty Years

Genetics is a discipline that has successfully used abstractions to attack many of the most important problems of biology, including the study of evolution and how animals and plants develop. The power of genetics to benefit mankind was first recognized by the award of the Nobel Prize in physiology or medicine in 1933 to T. H. Morgan. In the 23 years that had intervened between the time Morgan introduced Drosophila as a new organism for the study of genetics and the award of the Prize, he and his students, especially, A. H. Sturtevant, C. B. Bridges, and H. J. Muller, had vastly extended the laws of Mendel as the result of a host of discoveries, to mention only a few: that the genes (Mendel’s factors) are arranged in a linear order and can be placed on genetic maps, that they mutate in forward and reverse directions, that they can exist in many forms, or alleles, and that their functioning can depend upon their position. Purely on the basis of breeding experiments, these early workers were able to deduce the existence of inversions and duplications, for example, before it became possible to demonstrate them cytologically. The list of their achievements is a long one and one that has been put into historical perspective by Sturtevant in A History of Genetics [1].