The discovery of the mounds is the latest evidence to show the extensive impact people had on the area. From their arrival 10,000 years ago they transformed the landscape when they began cultivating manioc and squash.
This led to the creation of 4,700 of the forest islands in what is now Llanos de Moxos in northern Bolivia, the team has found. This savannah area floods from December to March and is extremely dry from July to October, but the mounds remain above the water level during the rainy season allowing trees to grow on them. The mounds promoted landscape diversity, and show that small-scale communities began to shape the Amazon 8,000 years earlier than previously thought.
The research confirms this part of the Amazon is one of the earliest centres of plant domestication in the world. Using microscopic plant silica bodies, called phytoliths, found well preserved in tropical forests, experts have documented the earliest evidence found in the Amazon of manioc -10,350 years ago, squash -- 10,250 years ago, and maize -- 6,850 years ago. The plants grown on the forest islands were chosen because they were carbohydrate-rich and easy to cook, and they probably provided a considerable part of the calories consumed by the first inhabitants of the region, supplemented by fish and some meat.
The study, in the journal Nature, was conducted by Umberto Lombardo and Heinz Veit from the University of Bern, Jose Iriarte and Lautaro Hilbert from the University of Exeter, Javier Ruiz-Pérez from Pompeu Fabra University and José Capriles from Pennsylvania State University.
Umberto Lombardo, José Iriarte, Lautaro Hilbert, Javier Ruiz-Pérez, José M. Capriles, Heinz Veit. Early Holocene crop cultivation and landscape modification in Amazonia. Nature, 2020; DOI: 10.1038/s41586-020-2162-7
The onset of plant cultivation is one of the most important cultural transitions in human history. Southwestern Amazonia has previously been proposed as an early centre of plant domestication, on the basis of molecular markers that show genetic similarities between domesticated plants and wild relatives. However, the nature of the early human occupation of southwestern Amazonia, and the history of plant cultivation in this region, are poorly understood. Here we document the cultivation of squash (Cucurbita sp.) at about 10,250 calibrated years before present (cal. yr BP), manioc (Manihot sp.) at about 10,350 cal. yr BPand maize (Zea mays) at about 6,850 cal. yr BP, in the Llanos de Moxos (Bolivia). We show that, starting at around 10,850 cal. yr BP, inhabitants of this region began to create a landscape that ultimately comprised approximately 4,700 artificial forest islands within a treeless, seasonally flooded savannah. Our results confirm that the Llanos de Moxos is a hotspot for early plant cultivation and demonstrate that—ever since their arrival in Amazonia—humans have markedly altered the landscape, with lasting repercussions for habitat heterogeneity and species conservation.
