Return to the RNAi world: rethinking gene expression and evolution (Nobel Lecture).

length and yet capable of producing 300 progeny in three days by self-fertilization. One of the most beautiful things about C. elegans, immediately apparent upon viewing it under the microscope, is its transparency. Sydney Brenner recognized the importance of this attribute when deciding what organism to work on. As animals go, C. elegans is relatively simple, having only about a thousand cells in the adult organism. Indeed, the origin and fate of every cell, both in the embryo and adult, has been determined—an amazing accomplishment. At any stage of development, you can look at a cell and know where that cell came from, tracing its origin back in time to the first division of the embryo. It s a beautiful system. In fact, the researchers who work with C. elegans have their own lineage. Almost all of us can trace ourselves back to Sydney Brenner, who pioneered the modern genetic analysis of this organism. My particular ancestors, if you will, in the lineage of researchers are shown in Figure 2. I owe a tremendous amount of thanks to Dan Stinchcomb, for teaching me molecular biology and really being a fantastic mentor during my initial years in graduate school; Victor Ambros who, along with Dan, provided a wonderful joint laboratory at Harvard University where I did graduate work; and then Jim Priess, who taught me genetics, and was a tremendous mentor and a great friend out in Seattle where I conducted my postdoctoral research at the Fred Hutchinson Cancer Research Center. I owe a tremendous amount to these individuals. I ll show you more pictures of people I will need to thank as I go along. I want to get down to the theme of my talk today, which really is, in part, about how we continually underestimate the complexity of life. It s the correction of these underestima-