Publications
Publications
1.
Gerren, A., Coe, M. A., Yessoufou, K., Gaoue, O.G. (2026). Does plant form recapitulate its therapeutic function? A test for red sap plants. Journal of Ethnobiology and Ethnomedicine.
This paper provides a rare test of Doctrine of Signatures (DOS) theory in ethnobiology. DOS theory, which predicts that a plant's physical form (such as its color or structure) indicates its medicinal use, has often been dismissed as a primitive mnemonic aid rather than a primary driver of plant selection. This global study tested the signature that red sap plants treat blood disorders and found that such species are three times more likely to be used for conditions like hemorrhages and anemia than plants without the signature. Using Bayesian modeling and phylogenetic analysis, researchers demonstrated that this therapeutic application is specifically linked to the red color signature rather than the mere presence of resin, and that both the signature and therapeutic use are phylogenetically clustered, suggesting a non-random selection of plants based on shared evolutionary traits. This relationship is biologically grounded in the presence of red quinones and the alkaloid Taspine, secondary metabolites with established efficacy in wound healing and antihemorrhagic activity. Ultimately, research indicates that the DOS may have served as a source of inspiration for medicinal discovery in traditional ethnomedicine, where ancient observations of red sap resembling human blood led to experimental testing and the eventual confirmation of biological bioactivity.
2.
Coe, M. A., & Gaoue, O.G. (2025).Toward a road map for sustainable ayahuasca production using integral projection models. In McKenna, D. et al. (eds.) The Ethnopharmacological Search for Psychoactive Drugs: 55 Years of Research. Synergetic Press.
This paper examines the growing ecological threats to ayahuasca production caused by its global commercialization. The authors introduce Integral Projection Models (IPMs) as a vital tool to quantify how the source vine, Banisteriopsis caapi (Spruce ex. Griseb.) C.V. Morton, responds to increased harvest pressures in the Peruvian Amazon. Research reveals that while populations with low harvest rates can remain stable, over-exploitation of larger vines significantly drives population decline and reduces survival. The study highlighted also emphasizes that cloning and vegetative reproduction may fail to offset the loss of mature vines, potentially risking long-term genetic diversity. Ultimately, the researchers propose a multidisciplinary road map that integrates scientific data with Indigenous ecological knowledge to ensure the sustainable and respectful management of these sacred plants. This framework addresses the interconnected ecological, economic, and cultural dimensions essential for protecting the future of ayahuasca.
3.
Albuquerque, U. P., Cantalice, A. S., Magalhães, A. R., Coe, M. A., Gusmão, R. A. F., (2024). Embracing Methodological Issues in Ethnobiology and Overcoming Challenges. Acta Botanica Brasilica.
This article explores the methodological evolution of ethnobiology, advocating for a shift from purely descriptive studies toward a rigorous hypothetical-deductive approach. The authors highlight the necessity of integrating quantitative methods while cautioning against the risks of oversimplification and the inappropriate use of indices. They emphasize the critical importance of genuine replication and probabilistic sampling to avoid the pitfalls of pseudoreplication and ensure findings can be generalized. The article also highlights the need for precise spatial and temporal data to provide essential context for understanding how human societies interact with their environments. Furthermore, the researchers call for greater data transparency, urging peers to report effect sizes and sample characteristics rather than relying solely on p-values. Ultimately, the authors call for a shift in the discipline by helping to advance the scientific rigor while remaining respectful of its qualitative and cultural foundations.
4.
Coe, M. A., & Gaoue, O.G. (2023). Increased clonal growth in heavily harvested ecosystems failed to rescue ayahuasca lianas from decline in the Peruvian Amazon rainforest. Journal of Applied Ecology.
This research article investigates how commercial harvesting affects the population health of the ayahuasca liana (Banisteriopsis caapi Spruce ex. Griseb.) C.V. Morton in the Peruvian Amazon. The authors used integral projection models to compare plants under different levels of human pressure, discovering that heavy exploitation significantly reduces the survival of large, mature vines. While these plants attempted to compensate through increased clonal growth, this asexual reproduction was insufficient to stop overall population decline in the short and long term. The study highlights a shift from traditional Indigenous use to globalized demand, which threatens the species' resilience. Consequently, the researchers recommend conservation strategies that prioritize protecting larger lianas, vegetative reproductive individuals, and seedlings to help ensure the vine's survival. Thus, while liana populations show some biological flexibility, overexploitation may limit the vine’s ability to withstand the intensity of modern harvesting methods beyond sustainable levels.
5.
Coe, M. A., & Gaoue, O. G. (2021). Phylogeny explains why less therapeutically redundant species are not necessarily facing greater use-pressure. People and Nature.
This research article investigates how evolutionary history and cultural preference influence the harvest levels of medicinal plants in an Amazonian community. The authors test the utilitarian redundancy model, which predicts that species with unique medical functions tend to face the highest use pressure. By investigating medicinal plant species used by the Shipibo-Konibo, the study reveals that therapeutically redundant species experience heavy use unless specific community preferences shift that pressure toward therapeutically unique plants. Crucially, the researchers found that phylogenetic relatedness—the "family tree" or phylogeny of plants—is a vital predictor because closely related species often share the same chemical properties and therapeutic roles. The findings suggest that conservation strategies must account for these evolutionary links rather than solely looking at individual species' popularity. Ultimately, the study demonstrates that understanding the complex human-nature relationship requires integrating both traditional indigenous knowledge and modern ecological principles.
6.
Gaoue, O. G., Moutouama, J. K., Coe, M. A., Bond, M. O., et al. (2021). Methodological advances for hypothesis-driven ethnobotany. Biological Reviews.
This paper calls for a paradigm shift in ethnobiology toward theory-inspired and hypothesis-driven research. The authors highlight that while the field has traditionally focused on qualitative descriptions, it must now adopt advanced statistical modeling to better understand the mechanisms of human-nature interactions and to allow for global inferences. Key methodologies discussed include mixed-effects models to handle the complex hierarchical structure of ethnobiological data, structural equation modeling for identifying causation, phylogenetic analysis to account for species’ evolutionary relationships, and social network analysis to track knowledge transmission among human societies. By integrating these quantitative tools with traditional contextual data, the discipline can improve its scientific rigor and interdisciplinary relevance. The paper provides practical frameworks and R scripts to help researchers transition to these modern analytical techniques. Such methodological evolution is framed as essential for addressing conservation crises, enhancing the professional competitiveness of future ethnobiologists, and facilitating interdisciplinary collaborations.
7.
Coe, M. A., & Gaoue, O. G. (2020). Cultural keystone species revisited: Are we asking the right questions? Journal of Ethnobiology and Ethnomedicine.
This paper examines the cultural keystone species theory (CKS) in ethnobiology, which seeks to identify organisms that are fundamental to the identity and stability of human societies. Through a systematic literature review, the authors reveal that while the CKS concept has gained popularity over several decades, most research to date relies on subjective assessments rather than objective and replicable measurements. The findings indicate that fewer than 5% of studies use reproducible methods to identify these species, and none have directly and rigorously tested the theory's core predictions. Consequently, the authors argue for a paradigm shift toward standardized, quantitative approaches to minimize researcher bias. By developing robust testing frameworks, researchers can better understand the links between biological and cultural diversity to improve conservation efforts. Such a rigorous methodology will help identify the cultural and biodiversity consequences of the extinction or loss of specific species to a community's cultural integrity.
8.
Coe, M. A., & Gaoue, O. G. (2020). Most cultural importance indices do not predict species cultural keystone status. Human Ecology.
This study evaluates the predictive power of ethnobiological quantitative indices to accurately identify cultural keystone species within a Shipibo-Konibo community in the Peruvian Amazon. By analyzing twelve regularly used indices to predict species’ cultural importance, the researchers discovered that most indices are redundant and highly correlated, yet they generally fail to predict a species' true cultural value and cultural keystone criteria. The authors introduced a more comprehensive keystone status score that explicitly incorporates variables for cultural keystone species criteria including species’ irreplaceability, ethnotaxonomic diversity, and psycho-socio-cultural function to offer a more precise assessment. Their findings suggest that accounting for species’ evolutionary relatedness through phylogenetic controls significantly improves the accuracy of these predictive models. Ultimately, the study advocates for a cautious and critical approach to using simplified indices to represent the complex, multidimensional values of medicinal plants. This research highlights the necessity for objective, multi-method strategies to better inform community-driven conservation efforts and protect biocultural integrity.
9.
Gaoue, O. G., Coe, M. A., Bond, M., Hart, G., Seyler, B., & McMillen, H. (2017). Theories and Major Hypotheses in Ethnobotany. Economic Botany.
The paper provides a comprehensive review of the major theories and testable hypotheses that guide research in ethnobotany. It outlines the transition of ethnobotany from a descriptive-based field to a hypothesis-driven interdisciplinary science that explores the complex relationships between people and nature. Researchers emphasize the importance of using theoretical frameworks, often adapted from ecology and anthropology, to understand why specific plants are selected for medicinal or dietary purposes. The authors synthesize 17 major theories, such as the availability hypothesis and optimal defense theory, which link plant selection to factors like local abundance and chemical properties. Additionally, the authors examine how social dynamics, including age, gender, and urbanization, influence the retention or loss of traditional ecological knowledge. The authors also highlight how cultural mechanisms like taboos and the concept of keystone species impact both conservation efforts and community identity. Ultimately, this synthesis serves as a guide for future scholars to conduct more rigorous, theory-inspired research that moves beyond classical studies solely focused on data collection.
10.
Coe, M. A., & McKenna, D. J. (2017). Therapeutic potential of Ayahuasca. In Evidence-based Herbal and Nutritional Treatments for Anxiety Disorders. Springer.
This paper examines the therapeutic potential of ayahuasca, a psychoactive botanical brew traditionally used by indigenous Amazonian groups for spiritual and medicinal purposes. Researchers analyze how the drink’s unique pharmacological synergy—combining DMT with MAO-inhibiting alkaloids—allows it to influence brain chemistry by upregulating serotonin transporters. Current scientific evidence suggests that ritualistic and therapeutic use may effectively alleviate symptoms of depression, anxiety, and substance addiction without causing any long-term toxicity. The authors also address the legal and cultural complexities surrounding the brew, noting that international scheduling of DMT often hinders rigorous clinical studies. Despite these hurdles, the authors highlight successful outcomes from syncretic religious groups and specialized treatment centers that integrate traditional knowledge with modern psychotherapy. Finally, the paper highlights critical safety warnings, specifically regarding the dangerous risk of "serotonin syndrome" when ayahuasca is mixed with standard pharmaceutical antidepressants.
