Diverse mathematical knowledge among indigenous Amazonians.

We investigate number and arithmetic learning among a Bolivian indigenous people, the Tsimane', for whom formal schooling is comparatively recent in history and variable in both extent and consistency. We first present a large-scale meta-analysis on child number development involving over 800 Tsimane' children. The results emphasize the impact of formal schooling: Children are only found to be full counters when they have attended school, suggesting the importance of cultural support for early mathematics. We then test especially remote Tsimane' communities and document the development of specialized arithmetical knowledge in the absence of direct formal education. Specifically, we describe individuals who succeed on arithmetic problems involving the number five-which has a distinct role in the local economy-even though they do not succeed on some lower numbers. Some of these participants can perform multiplication with fives at greater accuracy than addition by one. These results highlight the importance of cultural factors in early mathematics and suggest that psychological theories of number where quantities are derived from lower numbers via repeated addition (e.g., a successor function) are unlikely to explain the diversity of human mathematical ability.

Teacher plants - Indigenous Peruvian-Amazonian dietary practices as a method for using psychoactives.

ETHNOPHARMACOLOGICAL RELEVANCE: Indigenous groups of the Amazon have developed intricate methods for the application of psychoactives, among which particularly the dieta or diet method of Peruvian-Amazonian traditional medicine stands out. It is a retreat-like intervention involving lengthy periods of social, behavioural, and alimentary restrictions, while ingesting specially prepared plant substances. The interplay of the dietary conditions and plants ingested sensitizes the dieter to receive healing, strength, guidance, and knowledge. From a clinical scientific point of view, the method has remained largely underexplored, but seems more pertinent than ever given the increasing interest in Amazonian psychoactive preparations including ayahuasca (Banisteriopsis caapi) and the burgeoning field of psychedelic-assisted therapies in general. AIM OF THE STUDY: This study offers a descriptive account and emic interpretation of the Peruvian-Amazonian dieta. More specifically we document in detail the procedure, its context and purpose of application, effects, modes of action, adverse effects, and risks, from the perspectives of a sample of Peruvian traditional healers. The Peruvian-Amazonian dieta is a multi-purpose method for making use of medicinal plants, many of which (but not all), are psychoactive; the current work especially focuses on its therapeutic applications in conjunction with psychoactives. METHODS: We interviewed 16 healers working in the Ucayali, San Martín, and Loreto provinces of Peru using a semi-structured interview approach. Interviews were audio-recorded and transcribed verbatim. The extensive data derived from these interviews were analysed by means of computer-assisted manifest qualitative content analysis using a theory-advancing approach. Over 500 coded text segments were categorized, resulting in 7 main theme clusters and corresponding sub-themes. RESULTS: The interviewed healers described a complex intervention with multifaceted applications (treatment, prevention, training) and effects in various domains (body, mind, spirit, energy). The process was portrayed as transformative, with benefits attributed to the effects of the so-called teacher plants in conjunction with the diet's conditions, along with the skill of the healer guiding the intervention. Further, a detailed risk assessment revealed sophisticated safety measures and tools designed to address adverse responses. The importance of adequate training of the healer that administers the diet was particularly highlighted in this context. CONCLUSIONS: The dieta is a central therapeutic concept and tool in Peruvian-Amazonian traditional medicine and a unique method for using psychoactive plants. Multidisciplinary health research that includes traditional treatment methods from Indigenous cultures, Amazonian and other, should not be neglected in the current global interest in psychedelic therapies; such research may in the long-term contribute to a more inclusive psychedelic research paradigm as well as healthcare practice in countries where rich traditional healing systems exist, and perhaps beyond. It may also contribute to the recognition of the Indigenous healers as not only historical forerunners, but also current leading experts in psychedelic medicine.