The Amazonian rainforest is still full of surprises. There are still new species of animal and insect being discovered there on a regular basis, and much of it remains unexplored by science. Researchers have recently uncovered an Amazonian treasure that stands above the rest in terms of size, historical significance and sheer mystery. Over four-hundred and fifty huge "geoglyphs" - large earthen designs made of soil or rock - have been revealed and nobody know what they were for.
The glyps are found over about five hundred square miles of rainforest in western Brazil, in the state of Acre. They managed to stay hidden under dense rainforest canopy for hundreds of years. They were discovered thanks to deforestation. A silver lining, perhaps.
The geometrical trenches and ridges are a puzzle. Almost no artifacts have been found near them, meaning that they probably weren't villages at any point. And they're not laid out in such a way that they could have served effectively as defense fortifications. And there is also evidence that they were rarely visited, meaning they may have played some kind of ceremonial role for the indigenous people that built them.
The glyphs are at least two thousand years old, according to the international team of archaeologists who are investigating them. And despite not knowing their original function, the scientists are hopeful that the geoglyphs will give them a better understanding of how native populations changed the rainforest.
James Q. Jacobs
"The fact that these sites lay hidden for centuries beneath mature rainforest really challenges the idea that Amazonian forests are 'pristine ecosystems,'" says Jennifer Watling, a lead member of the research team. "We immediately wanted to know whether the region was already forested when the geoglyphs were built, and to what extent people impacted the landscape to build these earthworks."
When they put together a picture of the area's fire and vegetation history over six thousand years, they concluded that the area's human population had a radical impact on bamboo forests and were themselves engaged in deforestation. They cleared large areas of rainforest to make room for the geoglyphs.
But their rendition of deforestation was very different than the modern slash-and-burn approach. They mostly only cut down valuable trees like palms.
According to Dr. Watling, "Despite the huge number and density of geoglyph sites in the region, we can be certain that Acre's forests were never cleared as extensively, or for as long, as they have been in recent years."
“Our evidence that Amazonian forests have been managed by indigenous peoples long before European Contact should not be cited as justification for the destructive, unsustainable land-use practiced today. It should instead serve to highlight the ingenuity of past subsistence regimes that did not lead to forest degradation, and the importance of indigenous knowledge for finding more sustainable land-use alternatives”.
It's a fascinating discovery, and one that will hopefully continue to yield new insights into the region's history.