Work

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. Eric Wieschaus and Christiane Nüsslein-Volhard studied the development of fruit flies and, around 1980, succeeded in identifying and classifying the 15 genes that direct the cells to form a new fly.