Daniel Hunt Janzen (born January 18, 1939, in Milwaukee, Wisconsin) is an American evolutionary ecologist, and conservationist. He divides his time between his professorship in biology at the University of Pennsylvania, where he is the DiMaura Professor of Conservation Biology, and his research and field work in Costa Rica. Janzen and his wife Winifred Hallwachs have catalogued the biodiversity of Costa Rica. Through a DNA barcoding initiative, Janzen and geneticist Paul Hebert have registered over 500,000 specimens representing more than 45,000 species, which has led to the identification of cryptic species of near-identical appearance that differ in terms of genetics and ecological niche. They helped to establish the Area de Conservación Guanacaste World Heritage Site, one of the oldest, largest and most successful habitat restoration projects in the world. Early life and education Daniel Hunt Janzen was born January 18, 1939, in Milwaukee, Wisconsin. His father, Daniel Hugo Janzen, grew up in a Mennonite farming community and served as Director of the United States Fish and Wildlife Service. His father and mother, Miss Floyd Clark Foster of Greenville, South Carolina, were married on April 29, 1937. Janzen obtained his B.Sc. degree in biology from the University of Minnesota in 1961, and his Ph.D. from the University of California, Berkeley in 1965. Career In 1963, Janzen attended a two-month course in tropical biology taught in several field sites throughout Costa Rica. This Advanced Science Seminar in Tropical Biology was the precursor to a Fundamentals in Tropical Biology course, which Janzen designed for the Organization for Tropical Studies (OTS), a consortium of several North American and Costa Rican universities. Janzen went back in 1965 as an instructor and has lectured in at least one of the three yearly courses every year since. Janzen taught at the University of Kansas (1965–1968), the University of Chicago (1969–1972), and the University of Michigan (1972–1976) before joining the faculty at the University of Pennsylvania. There he is the DiMaura Professor of Conservation Biology, and his research and field work in Costa Rica. Janzen has also held teaching positions in Venezuela (Universidad de Oriente, Cumaná in 1965–66; Universidad de los Los Andes, Mérida in 1973), and in Puerto Rico (Universidad de Puerto Rico, Río Piedras, 1969). Research Janzen's early work focused on the careful and meticulous documentation of species in Costa Rica, and in particular on ecological processes and the dynamics and evolution of animal-plant interactions. In