Through analysis of phytoliths (microscopic plant silica bodies), PhD student Lautaro Hilbert found that 4,000 years ago rice became more common in the shell mound.

Newly discovered geometric earthworks in the Amazon forest were a puzzle for archaeologists


Amazonian rice domesticated 4,000 years ago

Southwestern Amazonia was long thought to be the cradle of domestication of several important cultivated plants in lowland South America, such as manioc, peanut and chilli pepper. Recently, researchers from the University of Exeter have discovered that rice (Oryza sp.) had also been domesticated by Pre-Columbian peoples in the Amazon.

The discovery took place during analyses of microscopic plant remains from the Monte Castelo shell mound, located in the wetlands of the Guaporé River – an area where wild rice grows nowadays. Through analysis of phytoliths (microscopic plant silica bodies), PhD student Lautaro Hilbert found that, starting 4,000 years before present, rice became more common in the shell mound. Moreover, rice phytoliths became increasingly larger, suggesting the dwellers of the site were progressively selecting for larger varieties of the plant, leading to its eventual domestication. With the abandonment of the region following the arrival of Europeans, the domesticated variety of rice was lost.

Read the full article in Nature Ecology and Evolution

A missing link in Amazonian archaeology

Recently, the southern Amazonian forests have revealed many archaeological surprises. In the upland areas away from the major rivers, monumental earthworks have been discovered in the Brazilian state of Acre, in Bolivia, and in the Upper Xingu River. These new findings contradict the idea that the largest rivers were the only environments where high population densities could settle in the Amazon forest. Separated by as much as 900 km, the newly discovered geometric earthworks were a puzzle for archaeologists: despite their similarity, there was no proof of connection between them.

An international team led by Prof. José Iriarte of the University of Exeter has now set out to Brazil in order to find the missing link between the Amazonian monumental enclosures. Combining predictive modelling of archaeological sites, systematic analysis of satellite imagery, LiDAR technology and ground survey, the team will explore a new region in the Brazilian state of Mato Grosso in search of pre-Columbian earthworks. The project is funded by the National Geographic Society.