This riveting account of medical detective work traces the story of kuru, a fatal brain disease, and the pioneering scientists who spent decades searching for its cause. When whites first encountered the Fore people in the isolated highlands of colonial New Guinea during the 1940s and 1950s, they found a people in the grip of a bizarre epidemic. Women and children succumbed to muscle weakness, uncontrollable tremors, and lack of coordination, until death inevitably supervened. Facing extinction, the Fore attributed their unique and terrifying affliction to a particularly malign form of sorcery. The Collectors of Lost Souls tells the story of the resilience of the Fore through this devastating plague, their transformation into modern people, and their compelling attraction for a throng of eccentric and adventurous scientists and anthropologists. Battling competing scientists and the colonial authorities, the brilliant and troubled American doctor D. Carleton Gajdusek determined that the cause of kuru was a new and mysterious agent of infection, which he called a slow virus (now called prions). Anthropologists and epidemiologists soon realized that the Fore practice of eating their loved ones after death had spread the slow virus. Though the Fore were never convinced, Gajdusek received the Nobel Prize for his discovery. The study of kuru opened up a completely new field of medical investigation, challenging our understanding of the causes of disease. But The Collectors of Lost Souls is far more than a tantalizing case study of scientific research in the twentieth century. It is a story of how a previously isolated people made contact with the world by engaging with its science, rendering the boundary between primitive and modern completely permeable. It tells us about the complex and often baffling interactions of researchers and their erstwhile subjects on the colonial frontier, tracing their ambivalent exchanges, passionate engagements, confused estimates of value, and moral ambiguities. Above all, it reveals the "primitive" foundations of modern science. This astonishing story links first-contact encounters in New Guinea with laboratory experiments in Bethesda, Maryland; sorcery with science; cannibalism with compassion; and slow viruses with infectious proteins, reshaping our understanding of what it means to do science.