The Amazonian flora contains literally tens of thousands of species.  How had the Indians learned to identify and combine in this sophisticated manner these morphologically dissimilar plants that possessed such unique and complementary chemical properties? The standard scientific explanation was trial and error – a reasonable term that may well account for certain innovations – but at another level, as Schultes came to realize on spending more time in the forest, it is a euphemism which disguises the fact that ethnobotanists have very little idea how Indians originally made their discoveries.

The problem with trial and error is that the elaboration of the preparations often involves procedures that are either exceedingly complex or yield products of little or no obvious value.  Yagé is an inedible, nondescript liana that seldom flowers.  True, its bark is bitter, often a clue to medicinal properties, but it is no more so than a hundred other forest vines.  An infusion of the bark causes vomiting and severe diarrhea, conditions that would discourage further experimentation.  Yet not only did the Indians persist but they became so deft at manipulating the various ingredients that individual shamans developed dozens of recipes, each yielding potions of various strengths and nuances to be used for specific ceremonial and ritual purposes.

In the case of curare, Schultes learned, the bark is rasped and placed in a funnel-shaped leaf suspended between two spears.  Cold water is percolated through, and the drippings collect in a ceramic pot.  The dark fluid is slowly heated and brought to a frothy boil, then cooled and later reheated until a thick viscous scum gradually forms on the surface.  This scum is removed and applied to the tips of darts or arrows, which are then carefully dried over the fire.  The procedure itself is mundane.  What is unusual is that one can drink the poison without being harmed.  To be effective it must enter the blood.  The realization on the part of the Indians that this orally inactive substance, derived from a small number of forest plants, could kill when administered into the muscle was profound and, like so many of their discoveries, difficult to explain by the concept of trial and error alone.

The Indians naturally had their own explanations, rich cosmological accounts that from their perspective were perfectly logical: sacred plants that had journeyed up the Milk River in the belly of anacondas, potions prepared by jaguars, the drifting souls of shamans dead from the beginning of time.  As a scientist Schultes did not take these myths literally, but they did suggest to him a certain delicate balance. “These were the ideas,” he would write half a century later, “of a people who did not distinguish the supernatural from the pragmatic.” The Indians, Schultes realized, believed in the power of plants, accepted the existence of magic, and acknowledged the potency of the spirit.  Their botanical knowledge could not be separated from their metaphysics.

From One River, by Wade Davis.