J. Brett Hill is a visiting assistant professor in the Sociology/Anthropology department at Hendrix College in Conway, Arkansas. He has conducted numerous studies using Geographic Information Systems (GIS) to evaluate how environment structured the economic and social opportunities available to ancient farmers and herders, and how people degraded their environment. Gary M. Feinman is the curator of Mesoamerican anthropology at the Field Museum and is the author or editor of more than a dozen books, most recently Images of the Past, 5th edition, coauthored with T. Douglas Price.