In February of 2000, HHMI investigator S. Lawrence Zipursky was trying to sort out what he had originally expected would be a relatively simple problem. He and his colleagues at the University of California, Los Angeles (UCLA), had discovered a fruit fly gene that encoded a protein on the surface of nerve cells that helped them migrate and connect to the correct cells. The team was analyzing the makeup of that protein, which they called Dscam—for Down syndrome cell adhesion molecule—because of its similarity to a human protein of the same name. They were surprised to find a segment of the protein that did not match the human version and suspected the fruit fly gene might produce a few subtly different proteins.

Illustration: Tetrarchs 4:04 and 4:16 PM November 2001 From Guest. A Blind Spot book published by Powerhouse Books. Courtesy Blind Spot Artist representation. New York / www.blindspot.com