For decades, researchers have puzzled over the mystery of the origin of Ayahuasca, especially the question of how the synergy was discovered between the the two components of the brew: the vine (Banisteriopsis caapi) with a monoamine oxidase inhibiting (MAOI) action and the leaf (Psychotria viridis or Diplopterys cabrerana), which requires that MAOI action to make their dimethyltryptamine (DMT) orally active. Drawing from two years of fieldwork among Napo Runa Indian shamans, cross-dialect studies of Quechua, and the record of anthropological data, I contend that the botanical origin of B. caapi was on the Napo River; that the original form of Ayahuasca shamanism employed the vine Banisteriopsis caapi alone; that the shamanic use of Banisteriopsis caapi alone spread and diffused before the DMT-containing admixtures were discovered; that the synergy between B. caapi and Psychotria viridis was discovered in the region of present-day Iquitos, the synergy between B. caapi and Diplopterys cabrerana was discovered around the upper Putumayo River, and that each combination diffused from there; and that the discoveries of these synergies came about because of the traditional practice of mixing other medicinal plants with Ayahuasca brew. Among the Napo Runa, the Ayahuasca vine is considered “the mother of all plants” and a mediator and translator between the human and plant worlds, helping humans and plants to communicate with each other.