Utilitarian redundancy in local medical systems - theoretical and methodological contributions

The influence of exotic and native plants on illnesses with physical and spiritual causes in the semiarid region of Piauí, Northeast of Brazil

BACKGROUND

Local medical systems (LMS) include native and exotic plants used for the treatment of diseases of physical and spiritual nature. The incorporation of exotic plants into these systems has been the subject of many studies. In this context, an analysis was conducted on the influence of the origin of plants on diseases of physical and spiritual nature in order to evaluate the therapeutic versatility of native and exotic species in these therapeutic targets, to investigate whether exotic plants mainly fill gaps not met by native plants (diversification hypothesis), and identify which species are prioritized in the redundant targets in these two therapeutic groups in the rural community of Morrinhos, Monsenhor Hipólito, Piauí.

METHODS

Data collection took place in 2 stages. First, free lists and semi-structured interviews with local residents (n = 134) were conducted to survey plants used for therapeutic purposes and the associated illnesses. Then, another phase of interviews was carried out to evaluate the prioritization between native and exotic plants in redundant therapeutic targets. To test the diversification hypothesis (DH) in each group of illnesses, data were analyzed using generalized linear models (Poisson and Binomial GLMs); versatility was measured by the number of therapeutic indications and compared between resources using the Mann-Whitney test, and prioritization in each group was verified by comparing the proportions of native and exotic plants with the χ2 test.

RESULTS

One hundred and thirty-two species of plants were surveyed, being 71 exotic and 61 native, with indications for physical and spiritual illnesses. The results revealed that the diversification hypothesis did not explain the inclusion of exotic plants in the local medical system to treat physical or spiritual illnesses and that the therapeutic versatility of exotic and native resources in the two groups was also similar (p > 0.05). However, exotic plants were prioritized in illnesses with physical causes and native plants in illnesses with spiritual causes.

CONCLUSIONS

The local medical system presents similar and distinct patterns in the therapeutic targets, depending on the perspective evaluated. Therefore, it is necessary to investigate the patterns of use of medicinal plants in different sociocultural contexts in order to broaden the debate about the role of plant origin in the selection of treatments for illnesses with different causes.

Plant parentage influences the type of timber use by traditional peoples of the Brazilian Caatinga

Local populations select different plants to meet their demands, so that morphologically similar species can be more used for a given use. Herein, we seek to understand whether plant species that are phylogenetically closer together are used more similarly than distant species in the phylogeny. Ethnobotanical data were collected in five rural communities in a semi-arid region of Brazil. A total of 120 local experts were selected and interviewed using semi-structured questionnaires. The people's knowledge of plants was organized into usage subcategories. We estimated the redundancy values for the mentioned species, and we compiled data from the literature on the wood density values of the cited species. We constructed our phylogenetic hypothesis of useful plants and used comparative phylogenetic methods to estimate the signal. Our results showed a strong phylogenetic grouping for both tool handle and craft uses. We observed a moderate phylogenetic grouping in which related cited plants exhibit similar redundancy and a weak grouping in which cited plants present similar wood density values. Our results revealed the importance of using phylogeny for useful plants. We conclude the phylogenetic proximity of useful plants and the lower redundancy for some species in our study may suggest greater use pressure, given that few species fulfill the same function.

Local Knowledge and Use of Medicinal Plants in a Rural Community in the Agreste of Paraíba, Northeast Brazil

The use of medicinal plants is an important source of therapeutic resources in rural communities and the wide versatility of some species may attract interest for prospecting studies. The aim of this study was to record and analyze local knowledge and the use of medicinal plants in the rural community of Malícia, municipality of Araçagi, Paraíba State, Northeastern Brazil, applying quantitative methods to calculate the Relative Importance (RI) and the Informant Consensus Factor (ICF). Semistructured interviews were conducted with 46 heads of households. The interviews addressed questions about the used parts of the plants, therapeutic indications, and form of use. Therapeutic indications were classified into categories of body systems. The Relative Importance Index (RI) was calculated to verify the species versatility, and the Informant Consensus Factor (ICF) was calculated to verify the consensus of use among informants regarding the body systems. A total of 111 plant species were recorded, inside 101 genera and 47 families. Fabaceae (16 spp.), Lamiaceae, and Myrtaceae (each one with 7 spp.) were the most representative families. Mentha arvensis, Aloe vera, and Myracrodruon urundeuva had the highest RI. A high consensus of use was observed among the informants for neoplasms, nervous system diseases, and infectious and parasitic diseases. Leaves were the part most cited for medicinal use. Regarding the method of preparation, the decoction and the oral administration route stood out. Neoplasms and respiratory system diseases had the highest ICF values. The results indicate a diversified knowledge of the local pharmacopeia and the need for in-depth studies to corroborate the effectiveness of medicinal plants and to understand the dynamics of local knowledge.