amazon forest
What was the function of these geometrical geoglyphs is still unclear. Credit: Jenny Watling

Archaeologists Have Discovered More Than 450 Large Geometrical Geoglyphs in the Amazonian Rainforest

Ancient people built hundreds of huge, mysterious earthworks in the Amazonian rainforest more than two thousand years ago, transforming the forests in the process.

UK and Brazilian experts have found new evidence in Acre state in the western Brazilian Amazon that sheds some light on how indigenous people lived in the Amazon long before Europeans arrived in the region. Trees concealed the abandoned enclosures for centuries, but modern deforestation has resulted in the uncovering of more than 450 of these large geometrical geoglyphs.

The purpose of these enigmatic sites is still not understood. As very few artifacts were recovered during excavation, they are unlikely to have been villages. The layout also does not suggest that they had been built for defensive purposes. The current thinking among archaeologists is that they were used only infrequently, perhaps as ritual gathering places.

The structures are abandoned enclosures that occupy approximately 13,000 square kilometers. The common belief that the rainforest ecosystem has been untouched by humans is challenged by this discovery.

Jennifer Watling, a post-doctoral researcher at the Museum of Archaeology and Ethnography, University of São Paulo, carried out this research while she was studying for a PhD at the University of Exeter. Dr Watling noted that the idea that Amazonian forests are ‘pristine ecosystems` is strongly challenged by the fact that these sites had been concealed beneath the mature rainforest for centuries.

Geoglyph photo. Credit: Jenny Watling

Watling and her team immediately had two questions when the structures were discovered:

  1. To what extent was the landscape impacted when these earthworks were built?
  2. Was the region already forested when the geoglyphs were built?

The team members used state of the art methods and managed to reconstruct 6000 years of fire and vegetation history around two of the geoglyph sites. They found that the clearings that were made to build the geoglyphs were small and temporary, and that bamboo forests were heavily changed by humans for millennia.

The people of that time did not burning large swathes of forest, either for agricultural practices or for geoglyph construction, but rather transformed their environment by concentrating on economically valuable tree species such as palms, and then creating a type of market of useful forest products.

The team found enticing evidence that suggests that the biodiversity of some of the remaining forests in Acre may have been influenced to a large degree by these ancient ‘agroforestry’ practices. Dr. Watling did however note that it is certain that Acre’s forests were never cleared for as long, or as extensively, as they have been in recent times, in spite of the large density and number of geoglyph sites in the region,

Watling also strongly cautioned that the evidence that indigenous peoples have managed the Amazonian forests long before European Contact should not be used to justify the destructive and unsustainable land use practiced nowadays. It should rather serve to emphasize the importance of native knowledge for finding more ecologically sustainable land use alternatives and the ingenuity of past subsistence establishments that did not lead to wiping out forests.

The team dug up soil samples from a series of pits outside of, and within the geoglyphs, to conduct the study. From these samples, a type of microscopic plant fossil made of silica called ‘phytoliths’ was analyzed.

This enabled the team to reconstruct the following:

  • Carbon stable isotopes were used to determine how overgrown the vegetation was in the past.
  • Charcoal quantities were used to evaluate the amount of ancient forest burning.
  • Ancient vegetation.



  • Luke Peters

    There are a number of grammatical errors in this article. Combined with the sponsored ads, smells like clickbait.

    • Horsey Ebooks

      in search of… with lots of commercials will be right back

    • rabid_god

      I noticed that too. I am disappoint.

  • rabid_god

    This is a science news journal site. There is an expectation that articles should be written in a professional style and manner with proper grammar, spelling, and punctuation. I haven’t read many of the other articles on this site to determine whether or not the issue is pervasive, but can someone please correct this article instead of just deleting reader comments about the quality of the article? Thanks.

    • Clint Chapman

      How about you get the stick out of your ass and quit complaining,Dr. Professor…

      • TheFellClutch

        sit your old ass down and shut the fuck up. he is 100% correct about this. This is a professed science news journal and articles should be correctly written. it’s not being a stick in the mud, it’s basic common fucking sense.

      • rabid_god

        Haha. ^^^ This guy. Science News Journal’s target audience for poor writing.

    • Nathan Fitzer

      a lot of these types of articles are written by bots this one is probably just new and needs bugs worked out

      • rabid_god

        While it’s possible that a bot could have written this and other articles, there are also a lot of sites with poor and/or inexperienced content writers and editors. At the very least I would hope there would be a human editor who reviews and proofreads the content for quality and accuracy before publication. Otherwise, how could they be certain that the content even pertains to the topic?

  • Lael

    Those were not found in the Amazon rainforest. They were found in a deforested area that used to be the Amazon rainforest.

    • doktoroktober

      You just can’t see the forest for the lack of trees.

  • disqus_rYEoSWMZUy

    “The people of that time did not burning large swathes of forest”… thanks for deleting my earlier comment about the grammatical mistakes that you still haven’t fixed. Get it together, “sciencenewsjournal”.

  • Aurora

    Why geoglyphs ? Why look for ‘enigmatic’ solutions ?! If we found such structures in Europe, we’d recognise these as defensive circular embankments around a settlement. Perhaps the banks even kept floodwater out during the wet seasons ? Why don’t we consider the easy answer first ?