Jenny WatlingThe Amazonian rainforest was transformed over two thousand years ago by ancient people who built hundreds of large, mysterious earthworks. The ditched enclosures, in Acre state in the western Brazilian Amazon, were concealed for centuries by trees. Modern deforestation has allowed the discovery of more than 450 of these large geometrical geoglyphs.
The function of these mysterious sites is still little understood - they are unlikely to be villages, since archaeologists recover very few artefacts during excavation. The layout doesn't suggest they were built for defensive reasons. It is thought they were used only sporadically, perhaps as ritual gathering places.
The structures are ditched enclosures that occupy roughly 13,000 km2. Their discovery challenges assumptions that the rainforest ecosystem has been untouched by humans.
Dr Watling said: "The fact that these sites lay hidden for centuries beneath mature rainforest really challenges the idea that Amazonian forests are 'pristine ecosystems`.
The full article will be released in the Proceedings of the National Academy of Sciences of the USA and involved researchers from the universities of Exeter, Reading and Swansea (UK), São Paulo, Belém and Acre (Brazil). The research was funded by the Arts and Humanities Research Council, National Geographic, and the Natural Environment Research Council Radiocarbon Facility.