David YetmanDavid Yetman is Associate Research Social Scientist at The Southwest Center at the University of Arizona and author of Where the Desert Meets the Sea: A Trader in the Land of the Seri Indians (1988), Sonora: An Intimate Geography (1996), and Scattere Round Stones: A Mayo Village in Sonora, Mexico (1998). He is host of the PBS series "The Desert Speaks." Thomas R. Van Devender is Senior Research Scientist at the Arizona Sonora Desert Museum. He has published many articles on the ecology and evolution of the Sonoran desert and has done pioneering research to determine ancient climates and vegetation change through studies of packrat middens. Read More Read Less