For nearly 1,500 years, the Aquiry civilization shaped southwestern Amazonia, and new research reveals it was far more populous than previously thought. Aerial laser scanning uncovered hundreds of ceremonial centers and the road systems. The civilization's impact is still visible in the Amazon's vegetation today.
conducted using airborne laser scanning reveals that a multicultural civilization flourishing in southwestern Amazonia between 600 BCE and 850 CE was home to millions of people. Spanning roughly 183,000 square kilometers, the Aquiry civilization built large centers for political and ritual purposes.
By surveying a representative section of the area, researchers identified the remains of more than 400 well-preserved sites of monumental ceremonial architecture, along with some later settlement sites.
Extrapolating their findings to the civilization's full territory, the researchers arrived at a cautious estimate of more than 20,000 ancient earthwork ceremonial centers. The largest known site covers 50 hectares.
Comprehensive surveys and radiocarbon dating showed that the Aquiry territory - which makes up less than 3 percent of Greater Amazonia - was already home to 1.25-3 million people at the start of the first millennium. This finding challenges earlier, more conservative estimates of the population across the wider Amazon region, which have ranged between 1 and 10 million. The Amazon's total population may have numbered in the tens of millions.
"Our findings overturn our understanding of the Amazon region's past," says , emeritus professor at the University of Helsinki who led the study.
Plants shaped by human hands
The Aquiry left their mark on the Amazonian landscape. They burned bamboo-dominated forest to clear land for fields of maize, squash, and manioc, for monumental ceremonial centers, and for the wide roads leading to them.
The Aquiry also practiced horticulture and managed valuable tree species.
"The research shows that the human impact on the Amazon's environment has been far greater than previously believed," Pärssinen notes.
Several protein-rich tree species in the region-including the Brazil nut tree, peach palm, also valued for its edible palm heart, and various other fruit-bearing trees-have been shown to result from long-term human interaction.
The Aquiry also promoted the spread of culturally significant trees at the expense of other species.
"This has direct implications for our understanding of the region's biocultural history. The civilization also affected ancient Amazonia's carbon production and carbon balance, which should be better accounted for in future climate models," Pärssinen adds.
Article continues after the picture.
Laser scanning reveals traces of land modification
The research was conducted using airborne laser scanning, or LiDAR. This technology maps land forms beneath vegetation and revealed thousands of traces of the ancient civilization in previously unstudied parts of the rainforest. The laser scanning covered an area of about 4,500 square kilometers, more than half of which was used for systematic assessment of the civilization's earthworks.
"We flew long, roughly 450-kilometer straight transects, mapping a strip about one kilometer wide every ten kilometers. This allowed us to cover as large a continuous area as possible," says Professor Juha Hyyppä of the Finnish Geospatial Research Institute (National Land Survey of Finland), who was responsible for the study's technical execution.
The detected features include large geometric shapes and straight roads.
"Their varying dimensions, shapes, construction methods, and locations reflect the distinct geographical and cultural characteristics of the region", notes Risto Kalliola, emeritus professor at the University of Turku.
According to native oral traditions, these centers were built to foster relations among communities and with significant other beings, while also serving as venues for gatherings, political decision-making, and displays of chiefly generosity. Ceremonies included ritual dance, music, feasting, athletic contests, and ball games.
A civilization without stone ruins
Relatively little is still known about the Aquiry civilization. Its territory was roughly equivalent in size to modern day Syria. Because the region lacks stone, no stone ruins remain, but the monumental geometric earthworks - known as Amazonian geoglyphs - nonetheless reveal the scale of the civilization.
The name Aquiry comes from the name Indigenous peoples used for the Acre River. "This was not a single realm but a network of many different communities", notes , professor of Indigenous studies at the University of Helsinki.
It is not known what languages were spoken across these communities, nor what they called themselves.
Nor is it known what caused the civilization's apparently rapid collapse around 850 CE. Around the same time, the classic Maya civilization in Central America also collapsed relatively abruptly.
The research was carried out by the University of Helsinki, the National Land Survey of Finland, the University of Turku, University of Aarhus and local partners. The project was coordinated by the Instituto Iberoamericano de Finlandia, together with the Factum Foundation (Madrid), with funding from a US-based donor.
The Article was published in Nature.
