New laser scanning finds massive geometric earthworks, suggesting populous pre-colonial society that \u2018resembled ancient Greece\u2019<\/p>\n
Archaeologists have uncovered hundreds of vast earthworks in the Amazon rainforest, which they say are evidence of a \u201clost civilisation\u201d that flourished nearly 2,000 years ago, said New Scientist.<\/p>\n
Researchers believe the geometrically patterned structures, known as geoglyphs, were built by an advanced pre-colonial society, known as the Aquiry, between 600BC and AD850 \u2013 without metal tools or animals. But they are almost impossible to detect under the dense tree canopy of the deep rainforest.<\/p>\n
The scientists used cutting-edge airborne laser scanning technology and found hundreds of previously unknown earthworks. They combined the light detection and ranging (LiDAR) data with previous findings to estimate that there might be up to 30,000 structures across the Aquiry territory. The results \u201cstrongly suggest\u201d that at its peak, the civilisation may have numbered 1.25 to 3 million, they wrote in a study published in Nature.<\/p>\n
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Indigenous people have known about some of the earthworks for generations, \u201cregarding some as sacred\u201d, said The Times. Archaeologists first identified several in the western Brazilian state of Acre in 1977, when deforestation began to clear parts of the forest. In 2003, archaeo-anthropologist Martti P\u00e4rssinen, from the University of Helsinki, and his team flew overhead and observed ancient straight roadways connecting the sites, in a region that had long been regarded as \u201cvirtually untouched\u201d.<\/p>\n
\u201cIt was a common idea that the Amazonian forest was a virgin wilderness, occupied only by small groups of hunter-gatherers,\u201d said P\u00e4rssinen, the study co-author. \u201cThese earthworks totally change our understanding of the supposedly pristine Amazon.\u201d<\/p>\n
P\u00e4rssinen theorised that the earthworks had been built by a complex, pre-Columbian civilisation. In 2021, he \u201cofficially introduced the name Aquiry\u201d, said LiveScience, after the Indigenous name for the Acre River, which flows from Peru and Bolivia into Brazil.<\/p>\n
In 2024, his team used aerial photographs and satellite imagery to count nearly 1,300 structures across southwestern Amazonia. But \u201cthe full scale remained lost beneath the trees\u201d, said ScienceAlert. LiDAR technology \u201cchanged everything\u201d.<\/p>\n
The team flew over around 1,700 square miles, firing rapid laser pulses at the ground. Some pulses penetrate gaps in the forest canopy and bounce off the ground, reflecting back to the sensors. Computers can use that to create \u201ca three-dimensional map of the ground under most vegetation\u201d, said New Scientist.<\/p>\n
The survey revealed 432 geoglyphs \u2013 \u201cnearly 400 of which were completely new to science\u201d. The largest covered an area of nearly 50 hectares. \u201cThe scale and precision of these constructions is simply astonishing,\u201d said P\u00e4rssinen. An average-sized geoglyph would have required about 300 people to build and maintain it.<\/p>\n
P\u00e4rssinen\u2019s estimate of a population of up to 3 million people is bold, said Michael Heckenberger, from the University of Florida, but \u201cplausible and extremely important, even mind-blowing\u201d.<\/p>\n
Over the past two decades, LiDAR has become \u201cone of archaeology\u2019s most exciting modern tools\u201d, said National Geographic. It has been credited with driving an \u201carchaeology revolution\u201d. In the early 2010s, archaeologists were \u201castonished\u201d when it revealed a lost Maya city.<\/p>\n