Ecology, Cognition, and Cultural Transmission of Tzeltal
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ECOLOGY, COGNITION, AND CULTURAL TRANSMISSION OF TZELTAL MAYA MEDICINAL PLANT KNOWLEDGE by DAVID GREGORY CASAGRANDE (Under the direction of Brent Berlin) ABSTRACT The goal of this dissertation is to explain patterns in the distribution of medicinal plant knowledge among the Tzeltal; in particular, why some plants are more likely to be known for their medicinal use than other plants. Methods included botanical collection, structured ethnobotanical surveys, landscape vegetation surveys, discourse analysis and participant observation. The explanatory approach was synthetic, drawing on notions from cultural anthropology, ethnopharmacology, ecology, cognitive science, linguistics, and studies of cultural transmission. Explanatory notions were tested by comparing Tzeltal Maya who have lived in the temperate Chiapas Highlands for many generations with other Tzeltal who have migrated from the Highlands to the lowland tropical rainforest within the last 30 years. Both study populations show patterns in which a few plants are known by every- one, but distribution of knowledge decreases as the diversity of plants increases, and most knowledge is idiosyncratic. The effects of typicality in categorization and discourse account for the few widely known plants. Humoral (hot/cold) classification is highly variable, does not facilitate recall of medicinal uses of plants, and has no significant effect on the distribution of knowledge. Cultural interpretations of plant taste and mor- phology are very important in individual cognitive models, but lose importance at the scale of shared discursive models where social and pragmatic themes also influence the dissemination of knowledge. While humoral classification and cultural interpretations of taste and morphology may be important for expert curers, they do not significantly affect the dissemination of knowledge among novices. Species that are more accessible tend to be used more often, and frequency of use is weakly correlated with knowledge distribu- tion. Emic perception of efficacy is the variable that most accounts for the distribution of knowledge. But social organization, individual cognition, and random processes in cul- tural transmission shape and bias the flow of information, and knowledge about many species that fit emic conceptions of efficacy is not distributed throughout the populations. INDEX WORDS: Chiapas, cognitive anthropology, cultural transmission, cultural models, goal-derived categories, prototypicality, distributed cognition, discourse, efficacy, ecological anthropology, ecology, ethnoecology, ethnopharmacology, ethnopharmacognosy, human ecosystems, humoral classification, indigenous knowledge, information, Maya, medical an- thropology, medical ethnobotany, medicinal plants, Mexico, organoleptics, phytosociology, social networks, Tseltal, Tzeltal, variation, migration ECOLOGY, COGNITION, AND CULTURAL TRANSMISSION OF TZELTAL MAYA MEDICINAL PLANT KNOWLEDGE by DAVID GREGORY CASAGRANDE B.S., Southern Connecticut State University, 1984 M.F.S., Yale School of Forestry and Environmental Studies, 1996 A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2002 © 2001 David Gregory Casagrande All Rights Reserved ECOLOGY, COGNITION, AND CULTURAL TRANSMISSION OF TZELTAL MAYA MEDICINAL PLANT KNOWLEDGE by DAVID GREGORY CASAGRANDE Approved: Major Professor: Brent Berlin Committee: Elois Ann Berlin Ben Blount Steve Kowalewski David Giannasi Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia December 2002 Dedication To Donna, whose patience and courage made this dissertation possible. And to my parents, Guido and Dorothy, for their enduring belief in my ability to do whatever I choose. iv Acknowledgments I am deeply grateful to Elois Ann and Brent Berlin for their advice and insights regarding research and life in general, and for providing access to the PROCOMITH data- base. Their generosity, patience, and steadfast commitment to their students, regardless of whatever difficult times may be at hand, serve as a model for all of us. I am also deeply grateful to my other doctoral committee members, Ben Blount, Steve Kowalewski and David Giannasi. All of their advice and comments over the years, however subtle, have contributed to this work. I am also forever indebted to the people of Nabil, Ch’ixaltontik, Tenejapa center, Maravilla Tenejapa, Salto de Agua, and Nueva Matsab for their hospitality, curiosity, will- ingness to share ideas and adventures, and all-around goodwill. Because of political ten- sions that continue to plague the Maya communities, I have decided not to list names. But I especially appreciate the efforts of my host family in Nabil, who opened their home and hearts to my colleagues and me. I am also grateful to those who assisted me with field research, transcription, and translation. I would like to thank the administration, staff and faculty of El Colegio de la Frontera Sur in San Cristóbal for agreeing to sponsor me as a visiting researcher and for their gener- ous help over the years. In particular, Dr. Mario González-Espinosa, the library staff, and Dr. Mario Ishiki and the staff of the herbarium have all been very helpful. One of the great advantages of choosing Highland Chiapas as a field site was the ability to share resources, ideas, and advice about research with other students and researchers while in the field. I am especially grateful to have had the opportunity to work in the field with Aaron Lampman, Cameron Adams, Anna Waldstein, George Luber, Scott Taylor, Rick Stepp, Tania Cruz Salazar, Stephanie Paladino, and Becky Zarger. v I am also grateful to have inherited the ability to build on a long tradition of research of Tzeltal medicine beginning with the work of Duane Metzger and Gerald Williams, and continuing with the work of Elois Ann and Brent Berlin and that of their students: John Brett, who studied the role of organoleptics; Luisa Maffi, who documented Tzeltal illness classification; George Luber, for his work on explanatory models; and Rick Stepp, who studied the effects of vegetation disturbance and habitats. Without the cumulative results of their meticulous work and thoughtful insights I simply would not have had the opportunity to ask the questions that I did in this dissertation I would also like to thank John Brett, Dan Moerman, and Glenn Shepard for sharing their insights about my research during the 2000 AAA meetings. Thanks also to George Luber and Rick Stepp for sharing their archival data and obscure literary sources with me. Some of the ideas in this dissertation, especially the themes of synthesis, the new ecology, and information, can be attributed to my participation in the Human Ecosystems Group at the University of Georgia. I would especially like to acknowledge the inspiration and advice provided by Dr. Charles Peters, who always admonished the need to “take the next step,” and Becky Zarger for her help and advice regarding cultural transmission. Other group members that I have not already thanked above include Eric Jones, Mitch Pavao- Zuckerman, Felice Wyndham, Suzanne Joseph, and Warren Roberts. This dissertation research was funded primarily by a National Science Foundation Doctoral Dissertation Improvement Award (BCS-0079499). Additional funding was pro- vided by the National Science Foundation Ethnographic Research Training Program ad- ministered through the University of Georgia, the UGA Maya International Collaborative Biodiversity Group, and a UGA Center for Latin American and Caribbean Studies Disserta- tion Travel Award. vi Table of Contents Acknowledgments.............................................................................................................. v Introduction......................................................................................................................... 1 Chapter 1 Ethnographic and Ecological Context..............................................................10 Chapter 2 Basic Methods and Fundamental Patterns of Knowledge Distribution...........41 Chapter 3 Epidemiological Context and Tzeltal Illness Classification............................59 Chapter 4 Knowledge Distribution and Emic Perceptions of Efficacy ............................81 Chapter 5 Salient Plant Characteristics and Medicinal Plant Knowledge........ ................99 Chapter 6 Humoral Classification, Mnemonics, and Knowledge Distribution.............122 Chapter 7 Effects of Medicinal Plant Abundance and Frequency of Use on Knowledge Distribution......................................................................................137 Chapter 8 The Influence of Individual and Distributed Cognitive Processes on Patterns of Agreement about Medicinal Plants...................................................152 Chapter 9 Structured Bias and Stochasticity in Cultural Transmission as the Primary Constraints of Knowledge Distribution.................................................207 Chapter 10 Conclusion: Major Findings and Significance for Ethnopharmacology and Ecological Anthropology...............................................................................247 References Cited..............................................................................................................261 Appendix A. Questions Asked During Structured Ethnobotanical Interviews................279 Appendix B. Plants Reported as Medicinal by two or more Interviewees