I swear, the spirits must read this blog. Just a day or so after I blogged about the importance of plant knowledge and the health costs of losing that knowledge, the Journal of Ethnobiology and Ethnomedicine published a comprehensive study of plant use in the culture area encompassed by northern Peru and southern Ecuador.

The study is by two distinguished scholars, ethnobotanist Rainer Bussmann and anthropologist Douglas Sharon, who had previously co-authored two significantly useful books — Plants of the Four Winds: The Magic and Medicinal Flora of Peru and Plants of Longevity: The Medicinal Flora of Vilcabamba. The present study was based on research earlier published here and here.

Rainer Bussmann

Northern Peru and southern Ecuador form a single culture area and share the same flora. Both are heirs of a regional plant healing tradition that goes back as far as the Cupisnique culture of the first millennium BC. But the two areas now show striking differences in plant knowledge and use.

The authors did a comprehensive survey — collecting, identifying, and recording vernacular names, traditional uses, and applications — of 510 plant species used for medicinal purposes in Peru and 215 plant species used for medicinal purposes in Ecuador. The number of species used as medicine indicates that the healers, market vendors, and members of the public whom the authors interviewed in Peru had considerable knowledge of plants in their surroundings, while in Ecuador much of this traditional plant knowledge appears to have been lost. Plants used as medicine in southern Ecuador comprise only forty percent of the species used in northern Peru.

How this difference came to be is particularly interesting.

Colonial chroniclers often included detailed descriptions of useful plants in their reports, and the authors reviewed both earlier and later compilations. In 1780, Martínez Compañon, Archbishop of Trujillo, had a complete inventory of the plants in his dioceses prepared, which covered much of the territory in the present study, and which contained 526 plant species. The work included detailed paintings of each plant, which the authors compared closely to the modern medicinal flora of the region, finding that the vernacular names of most plants had not changed since colonial times. In northern Peru, the number of medicinal plants did not seem to have changed significantly since the late 1700s — more than 500 species were found in both the Compañon survey and in modern Peruvian markets — while in southern Ecuador the number of plants used as medicine had declined significantly.

Douglas Sharon

A closer comparison, however, showed that only 41 percent of the plants described by Compañon were still sold in Peru; the remainder of the contemporary Peruvian pharmacopoeia had been added more recently. Even more, the plants used in Ecuador today remain most similar to those reported in the earlier rather than the later colonial herbals, as though plant knowledge there had become frozen at the time of colonization. This means that, from earliest colonial times, practitioners in both northern Peru and southern Ecuador stopped using a certain number of medicinal plants. But in Peru these plants were replaced by new ones, and in Ecuador the pharmacopoeia simply grew smaller.

So: why should this be? Bussmann and Sharon give a historical explanation. In Ecuador, the colonial Spaniards immediately began the persecution of traditional medical practitioners, while in Peru the colonial administration was much more tolerant. And this difference continued. In the 1980s, the Peruvian government established a National Institute for Traditional Medicine, while in Ecuador traditional medicine remained illegal until a constitutional amendment was passed in 1998. The persecution of traditional medical practitioners in Ecuador inhibited experimentation with new remedies, and the tradition withered.

The lesson here is worth emphasizing: the survival of a tradition of plant medicine lies not in its remaining static, but rather in its ability to experiment, innovate, and adapt. A static knowledge base inevitably shrinks. Persecution in Ecuador did not cause the loss of plant knowledge; it prevented the acquisition of new plant knowledge.

And a further implication is worth drawing as well. This finding runs directly counter to the common assumption that indigenous traditions today have survived through lack of change.