The beginning of plant cultivation is one of the most important cultural transitions in human history 1 – 4 . Based on molecular markers showing the genetic similarities between domesticated plants and wild relatives, south-western Amazonia has been proposed as one of the early centres of plant domestication 4 – 6 . However, the nature of the early human occupation and the history of plant cultivation in south-western Amazonia are still little understood. Here, we document the cultivation of Cucurbita at ca. 10,250 cal yr BP, Manihot at ca. 10,350 cal yr BP and Zea mays at ca. 6,850 cal yr BP in the Llanos de Moxos. We show that, starting ca. 10,850 cal yr BP, pre-Columbians created an anthropic landscape made of approximately 4,700 artificial forest islands within a treeless seasonally flooded savannah. Our results confirm the Llanos de Moxos as a hotspot for early plant cultivation and demonstrate that ever since their arrival, humans have caused a profound alteration of Amazonian landscapes, with lasting repercussions for habitat heterogeneity and species conservation.

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Phytolith analysis is increasingly used in archaeological and paleoecological research, yet the methods used to extract phytoliths from some types of sediments are still not completely satisfactory. This paper reports on the effect of adding sonication to protocols frequently used for phytolith extraction. We compare two common methods of phytolith extraction, both with and without part of the process being carried out in an ultrasound bath. Results show that sonication permits the destruction of soil micro aggregates and, in doing so, improves the removal of both soil organic matter and clay. Adding sonication to commonly used protocols for phytolith extraction is inexpensive and reduces the processing time and the need to use dangerous products, even with the samples that are most difficult to treat. Sonication increases the purity of the extracted phytoliths as well as augmenting the quantity of recovered phytoliths.

This study provides new data on the evolution of the landscape in southwestern Amazonia during the Holocene and the impact of climate change and fluvial dynamics on the region's ecosystems. Southwestern Amazonia is covered by an extensive seasonally flooded savannah, known as the Llanos de Moxos. Severe drought during the southern hemisphere winter, followed by months of permanent waterlogging, means that forests only grow on the most elevated parts of the landscape, mostly river and paleoriver levees and crevasse splays. Paleoclimate reconstructions from surrounding areas show that a shift to wetter conditions at around 4 kyr BP caused an increase in forest cover. However, the impact that this change in climate had on the landscape of the Llanos de Moxos is unknown. Published lacustrine archives from the area only cover the last 2 kyr. Here we present new data from the analysis of paleosols located along a 300 km transect across the central Llanos. The analyses of stable carbon isotopes, from 36 paleosols, and biogenic silica, from 29 paleosols, show that the patchwork of forests and savannahs that we see today was established after the 4 kyr BP climate change. During the dry period between 8 and 4 kyr BP, most of the central Llanos de Moxos, nowadays covered with seasonally flooded savannah, were covered by Cerrado-like savannah in the west and by forest in the east. However, results also suggest that, at both regional and local scales, vegetation cover has been influenced by changes in topography resulting from the region's river dynamics.

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