Kenneth A. Mason received his undergraduate degree in Molecular Biology from the University of Washington, worked at UC Berkeley, then pursued his PhD in Genetics at UC Davis. He has taught Gentics, Microbial Genetics, Microbiology, Advanced Molecular Genetics, Introductory Biology, and a Genetics Laboratory that he designed. George B. Johnson, Ph.D., is a professor of biology at Washington University in St. Louis and a professor of genetics at the university's School of Medicine. He is a prolific author of life science texts and curriculum products in a variety of media. New to his list of works are the Explorations of Human Biology CD-ROM and the textbook Human Biology, both offered by Wm. C. Brown Publishers. Johnson is acknowledged as an authority on population genetics and evolution variability, and he has published more than 50 research papers dealing with these and related topics. Visitors to the St. Louis Zoo can appreciate Johnson's work in the Living World, the educational center of which he is the founding director.