The largest and most endangered species in the Amazon rainforest is not the jaguar or harpy eagle, says Mark Plotkin, "but isolated tribes." In an overwhelming and sobering talk, the ethnobotanist takes us to the world of the indigenous tribes of the jungle and the amazing medicinal plants that shamans use to heal. It also points out the challenges and dangers that threaten these shamans and their wisdom, and alerts us that this irreplaceable repository of knowledge must be protected.