The Origins of Human Diet and Medicine: Chemical Ecology (Arizona Studies in Human Ecology)

People have always been attracted to foods rich in calories, fat, and protein; yet the biblical admonition that meat be eaten “with bitter herbs” suggests that unpalatable plants play an important role in our diet. So-called primitive peoples show a surprisingly sophisticated understanding of how their bodies interact with plant chemicals, which may allow us to rediscover the origins of diet by retracing the paths of biology and culture. The domestication of the potato serves as the focus of Timothy Johns’s interdisciplinary study, which forges a bold synthesis of ethnobotany and chemical ecology. The Aymara of highland Bolivia have long used varieties of potato containing potentially toxic levels of glycoalkaloids, and Johns proposes that such plants can be eaten without harm owing to human genetic modification and cultural manipulation. Drawing on additional fieldwork in Africa, he considers the evolution of the human use of plants, the ways in which humans obtain foods from among the myriad poisonous and unpalatable plants in the environment, and the consequences of this history for understanding the basis of the human diet. A natural corollary to his investigation is the origin of medicine, since the properties of plants that make them unpalatable and toxic are the same properties that make them useful pharmacologically. As our species has adapted to the use of plants, plants have become an essential part of our internal ecology. Recovering the ancient wisdom regarding our interaction with the environment preserves a fundamental part of our human heritage. __Originally published in hardcover as__ With Bitter Herbs They Shall Eat It: Chemical Ecology and the Origins of Human Diet and Medicine ## Review “A major contribution to our knowledge regarding the evolution of human diet.”— __Choice__ “The perspective is fresh and insightful. . . . Johns has turned over new ground and, in doing so, he has challenged us to think more longitudinally and creatively about the dietary choices we have made (and continue to make) as a species and their biological and sociocultural consequences.”— __American Anthropologist__ “Advances the state of ethnobiological thinking on the role of biochemistry in human-plant interactions. . . . A landmark book, and one that should encourage us all to look more carefully at nutritional chemistry and more broadly and deeply at the human condition.”— __Journal of Ethnobiology__ “It is a pleasure to read an interdisciplinary work that is solidly scientific yet flexible enough to brave new ground.”— __New Scientist__ ## From the Inside Flap People have always been attracted to foods rich in calories, fat, and protein; yet the biblical admonition that meat be eaten "with bitter herbs" suggests that unpalatable plants play an important role in our diet. So-called primitive peoples show a surprisingly sophisticated understanding of how their bodies interact with plant chemicals, which may allow us to rediscover the origins of diet by retracing the paths of biology and culture. The domestication of the potato serves as the focus of Timothy Johns's interdisciplinary study, which forges a bold synthesis of ethnobotany and chemical ecology. The Aymara of highland Bolivia have long used varieties of potato containing potentially toxic levels of glycoalkaloids, and Johns proposes that such plants can be eaten without harm owing to human genetic modification and cultural manipulation. Drawing on additional fieldwork in Africa, he considers the evolution of the human use of plants, the ways in which humans obtain foods from among the myriad poisonous and unpalatable plants in the environment, and the consequences of this history for understanding the basis of the human diet. A natural corollary to his investigation is the origin of medicine, since the properties of plants that make them unpalatable and toxic are the same properties that make them useful pharmacologically. As our species has adapted to the use of plants, plants have become an essential part of our internal ecology. Recovering the ancient wisdom regarding our interaction with the environment preserves a fundamental part of our human heritage. ## From the Back Cover The domestication of the potato serves as the focus of this synthesis of ethnobotany and chemical ecology. Johns considers the evolution of the human use of plants, the ways in which humans obtain foods from among the myriad poisonous and unpalatable plants in the environment, and the consequences of this history for understanding the basis of the human diet. ## About the Author Timothy Johns was appointed assistant professor of human nutrition at McGill University in 1987. He received his PhD from the University of Michigan, with his doctoral dissertation receiving the Distinguished Dissertation Award of 1985 from the Council of Graduate Studies in the United States/University Microfilms International. Cover Table of Contents Illustrations and Tables FIGURES TABLES Preface 1 A Model of Human Chemical Ecology INTRODUCTION CHEMICAL ECOLOGY ANIMAL AND PLANT FOODS IN CHEMICAL ECOLOGY EVOLUTION OF HUMAN DIETARY BEHAVIOR ORIGINS OF MEDICINE INTERACTIONS BETWEEN HUMANS AND PLANT CHEMICALS ETHNOBOTANY APPROACHES TO THE PROBLEM A MODEL OF HUMAN CHEMICAL ECOLOGY COMPONENTS OF THE MODEL 1. Humans seek to maintain physiological homeostasis through maximizing the beneficial effects of ingested components and minimizing the effects of potential toxins. 2. Natural selection has produced the interrelated physiological and behavioral mechanisms that allow humans to deal with environmental chemicals. Phylogenetic Considerations. Mechanisms for Dealing with Environmental Chemicals. Sensory perception. Physiological mechanisms 3. Humans have unique cultural traits that play a role in their interactions with plant (and animal) chemical constituents. Language and technological innovations, including plant domestication, are particularly powerful forces. Memory, Communication, and Culture. Communication. Technological innovation. 4. The nature of human interactions with plant (and animal) chemicals occurs within, and is influenced by, a broader ecological framework. TESTING THE MODEL POTATO DOMESTICATION AS A MODEL OF CHEMICAL SELECTION AYMARA INDIANS AND THE ALTIPLANO ENVIRONMENT EVOLUTION IN HUMAN AFFAIRS 2 Biological Adaptations for Dealing with Plant Toxins TASTE AND SMELL PERCEPTION OF PLANT ALLELOCHEMICALS NEOPHOBIA SENSORY-SPECIFIC SATIETY CONDITIONED RESPONSES DYNAMICS OF BIOLOGICALLY ACTIVE COMPOUNDS INGESTED BY ANIMALS BIOCHEMICAL BASIS OF DETOXICATION BACTERIAL TRANSFORMATIONS NATURAL SUBSTRATES OF DETOXICATION ENZYMES INTERACTION OF BEHAVIOR AND DETOXICATION SYSTEMS NATURALLY OCCURING TOXINS CYANOGENIC GLYCOSIDES GLUCOSINOLATES ALKALOIDS GLYCOSIDES OF TRITERPENES Saponins. Cardiac Glycosides. Glycoalkaloids. CUCURBITACINS METHYLAZOXYMETHANOL GLYCOSIDES PHYTOHAEMAGGLUTININS (LECTINS) INHIBITORS OF DIGESTIVE ENZYMES TANNINS AND OTHER PHENOLICS OXALATES AND PHYTATES BACTERIAL AND FUNGAL CONTAMINANTS OF FOOD MECHANISMS OF DETOXIFICATION VOMITING GEOPHAGY POTATO TOXICITY 3 Technological Methods of Detoxification TECHNICAL METHODS OF DETOXIFICATION HEATING SOLUTION FERMENTATION ADSORPTION DRYING PHYSICAL PROCESSING pH CHANGE PATTERNS OF DETOXIFICATION TECHNIQUES OF POTATO DETOXIFICATION DETOXIFICATION OF PLANTS BY CLAY Mineralogical and Chemical Characteristics of Clays. GEOPHAGY AND POTATO DOMESTICATION SOURCES OF CLAY SAMPLES CHARACTERIZATION AND ADSORPTIVE CAPACITIES OF POTATO CLAYS DETOXIFICATION UNDER PHYSIOLOGICAL CONDITIONS THE EVOLUTIONARY SIGNIFICANCE OF GEOPHAGY BY HUMANS 4 Domestication as a Solution for Dealing with Plant Toxins CHARACTERISTICS OF DOMESTICATED PLANTS 1. Gigantism. 2. Wide range of morphological variability. 3. Wide range of physiological adaptation. 4. Suppression of protective mechanisms. 5. Reduction in cross-pollination. CHANGES IN CHEMICAL DEFENSES CHEMICAL SELECTION AS A WORLDWIDE PHENOMENON CHEMICAL SELECTION IN NEW WORLD DOMESTICATES PLANT SYSTEMATICS AND HUMAN BIOLOGY BREEDING SYSTEMS INHERITANCE AND BIOSYNTHESIS OF SECONDARY CHEMICALS HYBRIDIZATION HUMAN SELECTION BIOSYSTEMATIC INVESTIGATIONS CHEMOTAXONOMY AND CHEMICAL ECOLOGY TWO CASE STUDIES CASE I. AÑU AND MACA: INTERACTION OF BIOLOGICAL AND CULTURAL ASPECTS OF CHEMICAL SELECTION CASE 2. CHEMICAL SELECTION AND POTATO EVOLUTION The Solanum x ajanhuiri Complex. Numerical Studies of Potato Affinities. Relationships of wild and cultivated diploids. Relationships of S. acaule and the S. x ajanhuiri complex. Chemotaxonomic Data. Chemotaxonomic evidence from wild species of Solanum series Megistacrolobum. The Relationships of S. x ajanhuiri. Solanum X ajanhuiri and Heteroploidal Hybridization. Implications of the Biosystematic Data. Dynamics of Domestication. Field studies of the evolution of Andean potatoes. Insects as pollination vectors. Human activities and potato evolution. Variability among populations of S. x ajanhuiri. Genetic recombination and seed dispersal in Solanum ajanhuiri. Introduction of new genotypes into cultivation. Deliberate production of new varieties. Natural disaster and the procurement of new tuber seed. The evolution of chemical change in potatoes. 5 Human Perception, Cognition, and Behavior in Relation to Plant Chemicals FOLK BIOLOGICAL CLASSIFICATION: UTILITARIAN ASPECTS CROSS-CULTURAL PERSPECTIVES ON TASTE PERCEPTION CLASSIFICATION TASTE AND THE AYMARA CLASSIFICATION AND SELECTION OF POTATOES GLYCOALKALOIDS AND POTATO TASTE QUALITY TASTE PANEL TESTS OF POTATO QUALITY TASTE PERCEPTION PTC TASTE SENSITIVITY TASTE PERCEPTION OF TOMATINE AND SOLANINE-CHACONINE TASTE TAXONOMY DIETARY SURVEY DETERMINANTS OF AYMARA TASTE PREFERENCE AND CLASSIFICATION SENSORY CHARACTERISTICS OF TRADITIONAL DIETS SEEKING AN ECOLOGICAL EXPLANATION METHODOLOGY GLYCOALKALOID CONTENT AND POTATO TASTE QUALITY CHEMICAL SELECTION OF POTATO VARIETIES 6 Reconsidering the Model of Human Chemical Ecology CHEMICAL SELECTION AND STEPS IN THE DOMESTICATION OF THE POTATO TESTING THE MODEL OF HUMAN-PHYTOCHEMICAL INTERACTION APPROACHES IN HUMAN CHEMICAL ECOLOGY 7 Plant Chemical Defenses as Determinants of the Human Diet EVOLUTION OF THE HUMAN DIET LINES OF INVESTIGATION ARCHAEOLOGICAL EVIDENCE AND APPROACHES STUDIES RELATING TO PRIMATE FEEDING BEHAVIOR Taste Perception. Gut Morphology and Digestive Physiology. COMPARATIVE STUDIES AMONG MODERN HUMANS Omnivorous Behavior. Comparative Physiology and Biochemistry. Nutritional Requirements. Human Physiology and Behavior in Relation to Dietary Toxins. Sensory perception. Detoxication enzymes. Gastrointestinal malaise. Conditioned responses. Flavor variety in the diet. PLANTS AND PLANT CHEMICALS IN THE HUMAN DIET THROUGH HISTORY DIET, HUMAN CULTURE, AND THE CHEMICAL-ECOLOGICAL BALANCE IN THE LATE TWENTIETH CENTURY PLANT ALLELOCHEMICALS VERSUS PESTICIDES NUTRITION AND MODERN FOOD SELECTION FOOD PROCESSING AND NUTRITION 8 The Dietary Basis for the Origin of Human Medicine CHEMICAL-ECOLOGICAL BASIS OF MEDICINE PRIMATE STUDIES HUMAN MEDICINE BIOLOGICAL AND CULTURAL BASIS THE ARCHAEOLOGICAL AND HISTORICAL RECORD OF MEDICINE MEDICINE AMONG GATHERER/HUNTERS MEDICINE IN PREINDUSTRIAL SOCIETIES MEDICINE IN LITERATE SOCIETIES TRADITIONAL KNOWLEDGE OF PLANT CHEMISTRY AND PHARMACOLOGY IN RELATION TO DISEASE Knowledge of Poison. Traditional Concepts of Disease. Legends on the Origin of Medicine. ACQUISITION OF EMPIRICAL MEDICAL KNOWLEDGE BIOLOGICAL FOUNDATIONS LEARNING THROUGH CONSCIOUS ASSOCIATIONS MOTIVATION FOR MEDICINE INTERRELATIONSHIP OF MEDICINE AND FOOD THE ROLE OF LEAVES IN HUMAN EVOLUTION A LOOK TO THE FUTURE Appendix 1 - Classification of Traditional Plant Processing Techniques 1. No special detoxification techniques applied 2. Special detoxification techniques applied 2.1. Detoxification by heat. 2.2. Detoxification by solution 2.3. Detoxification by fermentation 2.4. Detoxification by adsorption 2.5. Detoxification by drying 2.6. Detoxification by physical processing 2.7. Detoxification by pH change Appendix 2 - Traditional Methods of Plant Detoxification Bibliography Index ABOUT THE AUTHOR