Edward B. Lewis
Among more advanced organisms, life begins when a fertilized egg divides and forms new cells which, in turn, also divide. Initially these cells appear identical, but in time, they begin to change. Some cells go to make up the heart, others nerve paths, and still others strands of hair, for example. Genes regulate this process. Edward Lewis studied fruit flies and in the 1970s he discovered, among other things, that the positions of the flies' bodily organs matched the corresponding genes' positions on the chromosome.
developmental biology, embryology, genetics