Estrutura e variação temporal no conhecimento de plantas medicinais na caatinga no Nordeste do Brasil

Abstract

Local ecological knowledge about medicinal plants is perhaps one of the most extensive topics of study in the science of ethnobiology. Of a complex nature, this information makes up a cultural domain that was undoubtedly the pillar of the adaptive evolution of the human species. Studies in the area that discuss the population patterns found in the distribution of this medicinal information, show that despite being often extensive and diverse, people end up remembering only a few species of plants known to all, a phenomenon called “consensus within diversity”. Despite the methodological efforts to delimit or assign weights and indices to ecological resources used and known by people, such as tools cultural importance, use value, salience, cultural significance, etc., few studies seek to unravel which system factors may be guiding the formation of this structure itself. Using the structural core of medicinal plants as a theoretical model, the objective of this thesis was to analyze the adaptive biases in the formation of the "consensus within diversity" phenomenon through two ways, in the first, to discuss whether the factors of medical systems related to the effectiveness and availability of medicinal plants and the frequency of diseases were related to the consensus. These three variables were what we considered to be critical for behaving adaptively in socioecological systems. In the second, to investigate how this consensus structure evolves over time. We carried out the data collection of the thesis in two moments: in 2017, carrying out a free list of medicinal plants and therapeutic targets with 73 residents of PARNA Catimbau, Pernambuco, Brazil, and asking them to give a score from 0 to 10 on the effectiveness and general availability of plants and the frequency of occurrence of recalled diseases. The second time of collection was in 2019, and on that occasion, I interviewed again 49 of the same 73 residents in 2017, repeating a free list of medicinal plants. Also in 2019, I selected a community to also collect free lists of medicinal plants from children. Regarding the first objective, the data showed that only the perceived effectiveness was the factor related to the formation of the structural core, corroborating with several studies in the literature. We argue that although the effectiveness factor is influential, studies show that other system factors must play their roles in cultural salience, and thus, future studies must be carried out to deepen this issue. Regarding the second objective, our data showed that two years is enough to change the cultural consensus on medicinal plants and that children do not consider the same plants as adults important. I seek to discuss this issue by pointing out the lack of longitudinal studies in ethnobiology and that perhaps the structural core is oriented towards resolving contingency issues of diseases within socioecological systems. Availability or ease of obtaining the resource, types of disease, frequency of use, etc., all have the potential to modulate the structural core of medicinal plants.