Hundreds of mysterious structures built on Earth more than two thousand years ago have been discovered in the Amazon rainforest.
These are mysterious giant circular grounds - also known as geoglyph - hidden under forest canopy for thousands of years and only revealed by deforestation.
Scientists have discovered more than 450 geoglyph scattered in the Amazon forests in the territory of Acre, western Brazil.
Giant mysterious circle - also known as geoglyph.
Although no precise answer has been given about the origin and purpose of these circles, scientists have hypothesized that they are used infrequently as religious rituals.
The giant circular ground above is reminiscent of the famous Stonehenge stone circle in Wiltshire, England, with a total area of up to 13,000 km 2 .
According to researchers from Britain and Brazil, these findings have changed our previous thinking about the untouched forests of the Amazon rainforest.
"The fact that buildings are hidden for centuries under these tropical canopy has challenged the perception of Amazon forests as" primitive ecosystems " , Dr. Jennifer Watling at Archaeological Museum and People Ethnicity, Sao Paulo University said.
"We immediately want to know if this area is actually planted when the construction geoglyphs and the extent of human influence on the landscape when building these grounds."
These circles can be used infrequently as religious rituals.
Researchers have reproduced the 6,000-year history of vegetation and fires around two geoglyph points, to study the great changes of ancient humans.
According to the researchers, ancient humans changed bamboo forests for a thousand years and created small, temporary vacant lands to build mysterious structures.
The team collected soil samples from the inner and outer pits of the geoglyphs.
They then analyzed "phytoliths " - a microscopic plant fossil made from silica (SiO 2 ). This allowed them to reconstruct ancient vegetation and charcoal, assessing the number of stable isotope and carbon isotopes, and determining how to 'open' the vegetation of the ancient people.
Stonehenge stone circle.
The survey showed that the ancient Aborigines did not create large-scale forest fires, whether built geoglyph or made agricultural.
Instead, they focus on economically valuable plants, such as palm trees, transforming their environment in the process to create a "prehistoric supermarket".
And, according to the researchers, the biodiversity of some of the remaining forests in Acre may be derived from ancient agro-forestry activities.
These findings will be published in the Proceedings of the Russian Academy of Sciences.