Evidence Shows Amazon Rainforest Was Home to Up to a Million People

Aerial photo of one of the structures at Jacó Sá site. (Image: University of Exeter)
Aerial photo of one of the structures at Jacó Sá site. (Image: University of Exeter)

Parts of the Amazon previously thought to have been almost uninhabited were really home to thriving populations of up to a million people, new research shows.

Archaeologists have uncovered evidence that there were hundreds of villages in the rainforest away from major rivers, and they were home to different communities speaking varied languages who had an impact on the environment around them.

Huge parts of the Amazon are still unexplored by archaeologists, particularly areas away from major rivers. People had assumed ancient communities had preferred to live near these waterways, but the new evidence shows this was not the case.

The discovery fills a major gap in the history of the Amazon, and provides further evidence that the rainforest — once thought to be untouched by human farming or occupation — has in fact been heavily influenced by those who lived in it.

Archaeologists from the University of Exeter found the remains of fortified villages and mysterious earthworks called geoglyphs — manmade ditches with strange square, circular, or hexagonal shapes. Experts still don’t know the purpose of these earthworks, as some show no evidence of being occupied. It is possible they were used as part of ceremonial rituals.

Geoglyphs and mounded ring villages. a LiDAR digital terrain model of the Jacó Sá site showing geometric ditched enclosures, walled enclosures and avenues. Scale bar = 100 m. b Aerial photo of one of the structures at Jacó Sá site. c Aerial photo of Fonte Boa site showing a mounded ring village with radiating roads (right) built next to an earlier geometric enclosure (left). Aerial photographs are part of the collection of CNPq research group Geoglyphs of Western Amazonia directed by Denise Schaan. Image: Nature Communications

Geoglyphs and mounded ring villages. a: LiDAR digital terrain model of the Jacó Sá site showing geometric ditched enclosures, walled enclosures, and avenues. Scale bar = 100 m. b: Aerial photo of one of the structures at Jacó Sá site. c: Aerial photo of Fonte Boa site showing a mounded ring village with radiating roads (right) built next to an earlier geometric enclosure (left). Aerial photographs are part of the collection of CNPq research group Geoglyphs of Western Amazonia directed by Denise Schaan. (Image: Nature Communications)

Archaeologists uncovered the remains in the current Brazilian state of Mato Grosso. By analysing charcoal remains and excavated pottery, they have found a 1,800 km stretch of southern Amazonia was continuously occupied from 1250 until 1500 by people living in fortified villages.

The experts estimate that there would have been between 1,000 and 1,500 enclosed villages, and two-thirds of these sites are yet to be found.

The new study shows there are an estimated 1,300 geoglyphs across 400,000 km2 of Southern Amazonia, with 81 found in the area surveyed as part of this research. Villages are often found nearby, or inside the geoglyphs.

Ditched enclosures of the UTB. a Typical position of ditched enclosures in the landscape, on plateaus overlooking rivers (site Mt-05); b Example of a small enclosure (site Z-Mt-29). Scale bar = 50 m; c Compound structure with a small enclosure in the interior of a larger one (site Z-Mt-05). Scale bar = 100 m; d Part of the site Z-Mt-04, showing the wavy pattern of ditch construction. Scale bar = 50 m; e Plan of a major regional centre, site Mt-07, with ditches outlined in black and mounds/walls outlined in white (Satellite image ©2018 Google, DigitalGlobe). Scale bar = 200 m; f Site Mt-04. Scale bar = 100 m. Image: Nature Communications

Ditched enclosures of the UTB. a: Typical position of ditched enclosures in the landscape, on plateaus overlooking rivers (site Mt-05); b: Example of a small enclosure (site Z-Mt-29). Scale bar = 50 m; c: Compound structure with a small enclosure in the interior of a larger one (site Z-Mt-05). Scale bar = 100 m; d: Part of the site Z-Mt-04, showing the wavy pattern of ditch construction. Scale bar = 50 m; e: Plan of a major regional centre, site Mt-07, with ditches outlined in black and mounds/walls outlined in white (Satellite image ©2018 Google, DigitalGlobe). Scale bar = 200 m; f Site Mt-04. Scale bar = 100 m. (Image: Nature Communications)

They are connected through a network of causeways and some have been elaborately constructed over many years. The earthworks were probably made during seasonal droughts, which allowed forests to be cleared.

Drier areas still had fertile soils, where farmers would have been able to grow crops and fruit trees like Brazil nuts. Dr Jonas Gregorio de Souza, from the University of Exeter’s Department of Archaeology, a member of the research team, said:

Professor José Iriarte, from the University of Exeter, another member of the research team, said:

Provided by: University of Exeter [Note: Materials may be edited for content and length.]

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