Evolutionary aspects that guide the cultural transmission pathways in a local medical system in Northeast Brazil

Most of the studies with a focus on pathways and biases of cultural transmission in different domains show that vertical transmission predominates over horizontal and oblique transmission, especially in traits linked to traditions and survival skills, such as local medicine. However, overestimation of the importance of vertical transmission has been an object of methodological criticism. Therefore, a statistical analysis with diachronic perspective may obtain more accurate results. The present study uses an eight-year time frame, as well as synchronous analysis, to study evolutionary aspects that guide the transmission pathways of a local medical system in northeast Brazil. We find that even with vertical transmission being predominant in the learning of information in this cultural domain, the evolutionary implications of this predominance may not be the same as that expected by the theory of cultural evolution. There is a substantial updating of knowledge through horizontal and oblique routes, guided primarily by a model-based bias on prestige and success, which is quite adaptive. Moreover, even when the information is passed vertically, the transmission is much more diffusive than conservative. Indeed, there is a small set of information that remains over time, known as a "structural core," but new information is aggregated continuously, preparing the system to adapt to new events. By analyzing the transmission routes of knowledge about medicinal plants, this study presents a new perspective on the evolutionary implications of cultural transmission.