Washington Soares Ferreira Júnior

Does plant species richness guarantee the resilience of local medical systems? A perspective from utilitarian redundancy.

Resilience is related to the ability of a system to adjust to disturbances. The Utilitarian Redundancy Model has emerged as a tool for investigating the resilience of local medical systems. The model determines the use of species richness for the same therapeutic function as a facilitator of the maintenance of these systems. However, predictions generated from this model have not yet been tested, and a lack of variables exists for deeper analyses of resilience. This study aims to address gaps in the Utilitarian Redundancy Model and to investigate the resilience of two medical systems in the Brazilian semi-arid zone. As a local illness is not always perceived in the same way that biomedicine recognizes, the term “therapeutic targets” is used for perceived illnesses. Semi-structured interviews with local experts were conducted using the free-listing technique to collect data on known medicinal plants, usage preferences, use of redundant species, characteristics of therapeutic targets, and the perceived severity for each target. Additionally, participatory workshops were conducted to determine the frequency of targets. The medical systems showed high species richness but low levels of species redundancy. However, if redundancy was present, it was the primary factor responsible for the maintenance of system functions. Species richness was positively associated with therapeutic target frequencies and negatively related to target severity. Moreover, information about redundant species seems to be largely idiosyncratic; this finding raises questions about the importance of redundancy for resilience. We stress the Utilitarian Redundancy Model as an interesting tool to be used in studies of resilience, but we emphasize that it must consider the distribution of redundancy in terms of the treatment of important illnesses and the sharing of information. This study has identified aspects of the higher and lower vulnerabilities of medical systems, adding variables that should be considered along with richness and redundancy.

Medicinal Plant Knowledge Richness and Sharing in Northeastern Brazil

Medicinal Plant Knowledge Richness and Sharing in Northeastern Brazil.Determining how knowledge of medicinal plants is distributed in a community has been a challenge in the field of ethnobotany in recent years. Comparing the richness of knowledge and levels of sharing of such information is required in order to understand the patterns of knowledge and use of medicinal plants in traditional communities. This study evaluates the richness and level of knowledge sharing of medicinal plants among the inhabitants of a rural community in the Caatinga region of Pernambuco, Brazil. Knowledge richness and sharing was measured by the knowledge richness index (KRI) and the knowledge sharing index (KSI), which are simple tools to assess the distribution of local knowledge. We found that the community sustains a pharmacopoeia rich in medicinal plants, but that this plant knowledge is not uniformly distributed among community members. Based on the calculated indices, a significant relationship between the richness of knowledge, gender, and age of informants was not discovered. However, occupation was an important factor in the knowledge of medicinal plants, as residents with jobs related to land use had a greater knowledge in this area. The study also indicated that the formation of experts in the community, based on either knowledge of a large number of plants or of exclusive knowledge of particular plants, did not have a direct relationship with age or gender.Compartilhamento e Riqueza de Conhecimento de Plantas Medicinais no Nordeste do Brasil.Compreender como está distribuído o conhecimento sobre plantas medicinais em uma comunidade é um dos novos desafios da etnobotânica nesses últimos anos. Aliado a isso, comparar riquezas e níveis de compartilhamento destas informações faz-se necessário para definir os padrões de conhecimento e uso de plantas medicinais em comunidades tradicionais. Este trabalho objetiva avaliar por meio de índices de valoração a riqueza de conhecimento sobre plantas medicinais e o nível de compartilhamento do conhecimento sobre plantas medicinais entre os habitantes de uma comunidade rural na Caatinga pernambucana, Nordeste do Brasil. A riqueza e compartilhamento do conhecimento foram medidos através do índice de riqueza do conhecimento (KRI) e do índice de compartilhamento do conhecimento (KSI), os quais são índices recentes em estudos etnobiológicos, representando ferramentas simples para avaliar a distribuição do conhecimento em um grupo humano. Apesar de a comunidade ter uma farmacopéia tradicional rica em plantas medicinais, o conhecimento não é distribuído uniformemente, uma vez que foi observado um baixo compartilhamento do. Não foram observadas relações estatisticamente significativas entre a riqueza de conhecimento, gênero e idade dos informantes, ocorrendo uma fraca relação entre a idade e o número de plantas mencionadas pelos informantes. Entretanto, a ocupação foi um fator importante no conhecimento de plantas medicinais, considerando que agricultores apresentaram um maior conhecimento.

Plant Stem Bark Extractivism in the Northeast Semiarid Region of Brazil: A New Aport to Utilitarian Redundancy Model

We use the model of utilitarian redundancy as a basis for research. This model provides predictions that have not been tested by other research. In this sense, we sought to investigate the stem bark extraction between preferred and less-preferred species by a rural community in Caatinga environment. In addition, we sought to explain local preferences to observe if preferred plants have a higher content of tannins than less-preferred species. For this, we selected seven preferred species and seven less-preferred species from information obtained from semistructured interviews applied to 49 informants. Three areas of vegetation around the community were also selected, in which individuals were tagged, and were measured the diameter at ground level (DGL) diameter at breast height (DBH), and measurements of available and extracted bark areas. Samples of bark of the species were also collected for the evaluation of tannin content, obtained by the method of radial diffusion. From the results, the preferred species showed a greater area of bark removed. However, the tannin content showed no significant differences between preferred and less-preferred plants. These results show there is a relationship between preference and use, but this preference is not related to the total tannins content.

The Influence of the Environment on Natural Resource Use: Evidence of Apparency

This chapter evaluates the mechanisms by which certain characteristics of a specific natural resource (particularly a plant), such as its environmental availability or chemical composition, can affect its local use. An evaluation of the factors that influence people’s decision to select and try a natural resource and, possibly, incorporate it in their social-ecological systems is the main guiding issue for this chapter. To address this issue, we explore the assumptions of the ecological apparency hypothesis (EAH), the optimal foraging theory (OFT) and the resource availability hypothesis (RAH). EAH, OFT and RAH were first introduced in classic ecological research but were subsequently adapted to the fields of human ecology and ethnobiology. We also discuss how these ideas can complement one another to explain people’s choices for plant resource use and management. Finally, we bring some evidence from the available literature in favor or against these assumptions, especially to what concerns the EAH.

Utilitarian Redundancy: Conceptualization and Potential Applications in Ethnobiological Research

The utilitarian redundancy model (URM) enables a simple and objective evaluation of the functionality of knowledge systems based on species known to perform similar functions. It emerges from the redundancy model in ecology that analyzes, from a functional perspective, the use of natural resources by human populations. The model includes three basic assumptions. The first is that several species exist with the same function (redundancy), which leads to a shared use pressure among these similar species. Second, locally preferred species experience higher use pressure even if their function is redundant, and third, functional redundancy provides flexibility to cope with disturbances caused by local species loss and positively contributes to the resilience of social-ecological systems. The applicability of this model is explained in this chapter, primarily through examples of local medical systems, and its applicability to studies focusing on the resilience of traditional ecological knowledge systems is detailed.

Why do people use exotic plants in their local medical systems? A systematic review based on Brazilian local communities

Efforts have been made to understand the processes that lead to the introduction of exotic species into local pharmacopoeias. Among those efforts, the diversification hypothesis predicts that exotic plants are introduced in local medical systems to amplify the repertoire of knowledge related to the treatment of diseases, filling blanks that were not occupied by native species. Based on such hypothesis, this study aimed to contribute to this discussion using the context of local Brazilian populations. We performed a systematic review of Brazilian studies up to 2011 involving medicinal plants, excluding those studies that presented a high risk of bias (because of sampling or plant identification problems). An analysis of similarities (ANOSIM) was conducted in different scales to test for differences in the repertoire of therapeutic indications treated using native and exotic species. We have found that although there is some overlap between native and exotic plants regarding their therapeutic indications and the body systems (BSs) that they treat, there are clear gaps present, that is, there are therapeutic indications and BSs treated that are exclusive to exotic species. This scenario enables the postulation of two alternative unfoldings of the diversification hypothesis, namely, (1) exotic species are initially introduced to fill gaps and undergo subsequent expansion of their use for medical purposes already addressed using native species and (2) exotic species are initially introduced to address problems already addressed using native species to diversify the repertoire of medicinal plants and to increase the resilience of medical systems. The reasons why exotic species may have a competitive advantage over the native ones, the implications of the introduction of exotic species for the resilience of medical systems, and the contexts in which autochthonous plants can gain strength to remain in pharmacopoeias are also discussed.

What Do We Study in Evolutionary Ethnobiology? Defining the Theoretical Basis for a Research Program

Many scientific fields investigate the relationship between humans and nature from different perspectives and with a wide range of questions. These fields include, for example, human ecology, human behavioral ecology, and evolutionary psychology, and they are linked through the fact that they all adopt ecological and/or evolutionary hypotheses to understand this phenomenon. In this paper, we define for the first time the field of evolutionary ethnobiology, which seeks to understand these relationships in a broad perspective, considering an interdisciplinary program that integrates the advances, tools, and insights from different scientific fields. This theoretical and methodological integration is necessary for the formation of theoretical bases in ethnobiology and in other areas that investigate the relationship between humans and nature.

Urbanization, Modernization, and Nature Knowledge

The process of urbanization and modernization has led to a growing approximation between local populations and urban environments. An important question in ethnobiology is to understand the effects that this process can exert on the knowledge of human groups regarding environmental resources. In this chapter, we discuss the effects of urbanization and modernization in local ecological knowledge, and we take the use of medicinal plants in local medical systems as an example to discuss the issue. Here, as well, we show evidence from studies demonstrating that urbanization processes negatively affect the knowledge of medicinal plants as well as the evidence to suggest that a negative effect on knowledge does not necessarily occur. In addition, we note certain mechanisms that are associated with the influence of urbanization on the knowledge of medicinal plants.

Niche Construction Theory and Ethnobiology

The focus of ethnobiological research is to understand the interactions between people and biota. Here we suggest that niche construction theory can provide an important “theoretical framework” for understanding these interactions from different perspectives. Niche construction is a process by which living beings, including humans, modify their own niches or those of other organisms through their activities and decisions. By altering their niches, organisms can also alter the natural selective pressures. In this chapter, we sought to explore the niche construction theory and its key concepts. We also sought to show how niche construction theory can illustrate the biological and cultural impacts of human populations on the environment and on its own species and how ethnobiology can benefit from this theory. Niche construction theory can serve as an integrating concept for different ethnobiological approaches.

Biological and Cultural Bases of the Use of Medicinal and Food Plants

The evidence of an overlap between food and medicinal uses of some plants may reflect a food–medicine continuum. In this chapter, we discuss the role that this continuum may have played in the evolution of our interactions with plants and the origin of medical traditions. Biological and cultural evidence suggest the means by which humans realized and accessed this continuum in the past, providing an important step in the origin of human medical systems. Finally, we argue that the study of the food–medicine continuum can provide an interesting theoretical scenario for ethnobiology investigations.