Thousands of treasures may await discovery in the Amazon

New laser scans are revealing that the world’s biggest rainforest may be hiding traces of far more human history than was previously believed.

The dense and humid Amazon rainforest is considered one of the most pristine regions on Earth, covering an area equivalent to around 70% of Australia’s land mass, and home of many thousands of unique species.

But there are new indications that this humid wilderness and the thin layer of soil that nourishes it may have seen far more human intervention than scientists used to think.

A large team of researchers from the National Institute for Space Research in Brazil searched 5315km2 of the dense jungle using LIDAR – Light Detecting And Ranging – a technology in which an airplane or drone flies over the area emitting laser light. By analysing the reflected light, researchers can reveal ground elevation differences and make a 3D map of the jungle.

LIDAR technology has enjoyed repeated successes in revealing ancient settlements from the Mayan in South America to the vast cities of the Khmer

Empire in what is now Cambodia. But this time researchers were surprised by the sheer extent of unexpected discoveries made in dense Amazon jungle during a single sweep of the 5315km2 area. A total of 24 previously unknown structures emerged from the LIDAR mapping.

The findings in the soil layers are believed to be the remains of civilisations that existed in the area 1500 to 500 years ago, including an ancient fortified village in the southern Amazon and a series of ceremonial areas in the northern Amazon, where large stone structures were found to be arranged in circles.

The survey covered only 0.08% of the total 6.7 million km2 of rainforest. So the researchers also created a computer model to predict how many archaeological treasures might potentially be buried under the jungle.

For the model they took into account 937 structures that have already been discovered in previous surveys, and the concentration of ancient settlements in the new study. They also took other factors into account, such as distance from rivers, temperatures and rainfall, to determine where evidence of the lost civilisations is most likely to be hidden.

The researchers’ calculations show that there may be between 10,272 and 23,648 undiscovered settlements still hiding under the world’s largest jungle. If correct that would mean that 90% of human history in the Amazon is still waiting to be uncovered. As in Australia, Indigenous communities have called the region home for millennia, 12,000+ years in the case of the Amazon, so that construction of settlements and taming of landscapes will have had a long-lasting impact on the composition of the forest.

Ever more discoveries suggest that the communities were much larger than previously believed, but it is still unclear why the settlements and their inhabitants disappeared centuries ago.