The tribes of the Amazon present numerous riddles that are surely related to the difference between a qualitative and ana lytic understanding. There is a plant called yag whose bark contains the beta-carbolines, harmine and harmaline. By combining yag with various other plants, the shamans of the northwest Amazon long ago learned to concoct potent psychoactive drinks. Investigating two of the auxiliary plants employed in these concoctions, Schultes noted that they contained tryptamines, "powerful psychoactive compounds [writes Davis] that when smoked or snuffed induce a very rapid, intense intoxication of short duration marked by astonishing visual imagery." (Neither Schultes nor Davis was loath to verify such effects for himself.)
The problem is that, taken orally (the Indians drank these potions), the tryptamines have no effect; they are denatured by an enzyme in the human gut. But, as it turns out, the betacarbolines in yag inhibit exactly this enzyme. So when yag is combined with one of the admixture plants, the combination produces dramatic hallucinogenic effects.
What astonished Schultes was less the raw effect of the drugs by this time, after all, he was becoming accustomed to having his consciousness awash in color than the underlying intellectual question that the elaboration of these complex preparations posed. 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time in the forest, it is a euphemism which disguises the fact that ethnobotanists have very little idea how Indians originally made their discoveries.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. Yag 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 adept at manipulating the various ingredients that individual shamans developed dozens of recipes, each yielding potions of various strengths and nuances to be used for special ceremonial and ritual purposes.
Another example was the preparation of dart poison, known as "curare":
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.
Perhaps the trial-and-error hypothesis simply reflects a long habit of ignoring the knowledge potentials of an attention to the qualities of our environment. Such attention on the Indians' part could be quite remarkable. They recognized many different kinds of yag plants, all of which, so far as Schultes could tell, were referable to a single species. The distinguishing criteria made no sense botanically, and yet "the Indians could readily differentiate their varieties on sight, even from a considerable distance in the forest. What's more, individuals from different tribes, separated by large expanses of forest, identified these same varieties with amazing consistency."
Much the same was true of yoco, a caffeine-containing stimulant. Schultes collected fourteen different types by the Indians' reckoning, "not one of which could be determined based on the rules of his own science." Schultes, as Davis reports it, was learning that
in unveiling the indigenous knowledge, his task was not merely to identify new sources of wealth but rather to understand a new vision of life itself, a profoundly different way of living in a forest.