Jungle-penetrating lasers have peeked through the dense Amazonian rainforest to reveal the ruins of 11 previously unknown settlements decorated with vast pyramids and waterways.

As reported in the journal Nature today, scientists examined six areas within a 4,500 square kilometer (1,737 square mile) region of the Llanos de Mojos in the Bolivian Amazon using helicopter-mounted lidar imaging technology. In total, they discovered two new large settlement sites named Cotoca and Landívar, and 24 smaller sites – of which only 15 were previously known to exist. 

The settlements weren't merely a scattering of a few basic huts; it appears that some were once bustling communities with their own ceremonial architecture and complex water-management infrastructure composed of canals and reservoirs. Among these larger settlements of Cotoca and Landívar, the team even discovered vast platform mounds and cone-shaped pyramids measuring up to 22 meters (72 feet) tall. 

Their study indicates that the settlements date from approximately 500 CE to 1400 CE, when this portion of the Bolivian Amazon was home to the Casarabe culture.

It was once assumed that the Amazon rainforest was too wild and dense to support large-scale human settlements in pre-Columbian times. However, this idea has been widely challenged thanks to major discoveries in recent years revealing that the rainforest was once teeming with networks of complex settlements. 

“Our results put to rest arguments that western Amazonia was sparsely populated in pre-Hispanic times,” the study authors write.

Many of these discoveries have been made possible through lidar. First developed in the early 1970s for space exploration, this laser-based imaging technology has since proven an invaluable tool for archeologists scouring landscapes for long-lost settlements. Not only can it instantaneously scan huge areas, but it can also “see-through” thick vegetation and pick up on hints of human-made structures that have since been lost to time.  

“As with other tropical regions, the application of archaeological Lidar to the Amazon has launched a transformative process of discovery, documentation and reworking of assumptions held for decades regarding the nature of ancient societies,” Chris Fisher, an archaeologist and professor of anthropology at Colorado State University, who wasn’t directly involved with the study, wrote in an accompanying article. 

“[This] work is the opening salvo of an Amazonian new orthodoxy that challenges the current understanding of Amazonian prehistory and fundamentally enriches our knowledge of tropical civilizations.”

There is, no doubt, much left to rediscover in the Amazon – however, time is of the essence. Threatened by the climate crisis and rampant deforestation, the Amazon rainforest may not be so quick to give up its secrets in the future. 

“Unfortunately, given the rapid rate of ecological change that threatens not only ecosystems but also cultural resources, we are running out of time,” concluded Fisher. “If the Amazonian new orthodoxy is to be suitably documented before the archaeology vanishes forever, we must see many more large-scale lidar scans and studies like the one presented by Prümers and colleagues.”