Expanding the frontiers of Amazonian archaeology into the forest

Growing interest in long-term human history of Amazonia reflects the recognition that pre-colonial Indigenous societies shaped food-rich and persistent landscapes - an understanding that holds crucial implications for the region's socio-environmental conservation and sustainability. We integrated archaeological, archaeobotanical, paleoecological, and ecological approaches to investigate how and when the cultural landscapes of the Ponta da Castanha archaeological site, located within a highly heterogeneous forest mosaic in the Tefé National Forest (middle Solimões River basin, Amazonas, Brazil), were constructed. Going beyond settlement-centered perspectives, we approached living plant communities as cultural artifacts. We combined ceramic-based cultural chronologies and analyses of charred plant remains with phytolith, soil, and floristic analyses across five cultural landscapes recognized by local inhabitants: two Brazil nut ( Bertholletia excelsa ) stands, one Amazonian oil palm ( Elaeis oleifera ) stand, a transitional forest, and a mature forest. These five landscapes underwent highly dynamic and localized landscape transformations during at least five pre-colonial occupations that lasted over 3200 years. Phytolith signatures, archaeobotanical records, floristic compositions, and soil profiles indicate the introduction, promotion, and cultivation of crops, such as maize and squash, along with fire-based management and landscape clearing over time. These practices are evident from the earliest phase of occupation (Flona occupation, ca. 3200 - 2000 cal yr BP), despite low ceramic densities. The use of Brazil nut is documented since the beginning of human occupation, but the current dense Brazil nut stands seem to be a post-colonial phenomenon. Evidence of Amazonian oil palm use dates from the Late Tefé occupation (ca. 700–350 cal yr BP). Palm enrichment in the mature forest occurs throughout human occupation, intensifies during the Late Tefé occupation, and declines in the post-colonial period. By using a multi-proxy approach and integrating local perspectives, rooted in the inextricability of nature and culture, our study offers a practical framework for environmental archaeological research in tropical regions that expands and refines archaeological sampling and reveals the long-term, diverse, and place-specific landscape transformations that shaped today's heterogeneous forests in Amazonia.