amazon, lasers reveal ancient urban sprawl hidden in the amazon

A massive urban landscape that contained interconnected campsites, villages, towns and monumental centers thrived in the Amazon rainforest more than 600 years ago.

In what is now Bolivia, members of the Casarabe culture built an urban system that included straight, raised causeways running for several kilometers, canals and reservoirs, researchers report May 25 in Nature.

Such low-density urban sprawl from pre-Columbian times was previously unknown in the Amazon or anywhere else in South America, say archaeologist Heiko Prümers of the German Archaeological Institute in Bonn and colleagues. Rather than constructing huge cities densely packed with people, a substantial Casarabe population spread out in a network of small to medium-sized settlements that incorporated plenty of open space for farming, the scientists conclude.

Airborne lasers peered through dense trees and ground cover to identify structures from that low-density urban network that have long eluded land-based archaeologists.

Earlier excavations indicated that Casarabe maize farmers, fishers and hunters inhabited an area of 4,500 square kilometers. For about a century, researchers have known that Casarabe people fashioned elaborate pottery and constructed large earthen mounds, causeways and ponds. But these finds were located at isolated forest sites that are difficult to excavate, leaving the reasons for mound building and the nature of Casarabe society, which existed from about the year 500 to 1400, a mystery.

Prümers’ team opted to look through the Amazon’s lush cover from above, aiming to find relics of human activity that typically remain hidden even after careful ground surveys. The scientists used a helicopter carrying special equipment to fire laser pulses at the Amazon forest as well as stretches of grassland. Those laser pulses reflect data from the Earth’s surface. This technique, called light detection and ranging, or lidar for short, enables researchers to map the contours of now-obscured structures.

Looking at the new lidar images, “it is obvious that the mounds are platforms and pyramids standing on artificial terraces at the center of well-planned settlements,” Prümers says.

Prümers’ team conducted lidar surveys over six parts of ancient Casarabe territory. The lidar data revealed 26 sites, 11 of them previously unknown.

Two sites, Cotoca and Landívar, are much larger than the rest. Both settlements feature rectangular and U-shaped platform mounds and cone-shaped earthen pyramids atop artificial terraces. Curved moats and defensive walls border each site. Causeways radiate out from Cotoca and Landívar in all directions, connecting those primary sites to smaller sites with fewer platform mounds that then link up to what were probably small campsites or areas for specialized activities, such as butchering prey.

The Casarabe society’s network of settlements joins other ancient and present-day examples of low-density urban sprawl around the world, says archaeologist Roland Fletcher of the University of Sydney. These sites raise questions about whether only places with centralized governments that ruled over people who were packed into neighborhoods on narrow streets, such as 6,000-year-old Mesopotamian metropolises, can be defined as cities.

Some past urban settlements organized around crop growing spanned up to 1,000 square kilometers or more in tropical regions. These include locales such as Southeast Asia’s Greater Angkor roughly 700 to 800 years ago and interconnected Maya sites in Central America dating to at least 2,300 years ago (SN: 4/29/16; SN: 9/27/18). Today, extended areas outside large cities, especially in Southeast Asia, mix industrial and agricultural activities over tens of thousands of kilometers.

Clusters of interconnected Casarabe settlements ranged in area from 100 square kilometers to more than 500 square kilometers. Spread-out settlements of comparable area include 6,000-year-old sites from Eastern Europe’s Trypillia culture (SN: 2/19/20).

Tropical forests that have gone largely unexplored, such as Central Africa’s Congo Basin, probably hosted other early forms of low-density urban development, Fletcher predicts.

Only further excavations guided by lidar evidence can begin to untangle the size of the Casarabe population, Prümers says. Whether primary Casarabe sites represented seats of power in states with upper and lower classes also remains unknown, he adds.

Casarabe culture’s urban sprawl must have encompassed a considerable number of people in the centuries before the Spanish arrived and Indigenous population numbers plummeted, largely due to diseases, forced labor and slavery, says archaeologist John Walker of the University of Central Florida in Orlando.

Whatever Casarabe honchos had in mind as their tropical settlement network spread, he says, “we may have to set aside some of our strongly held ideas about what the Amazon is, and what a city is, to better understand what happened.”

Questions or comments on this article? E-mail us at feedback@sciencenews.org

Citations

H. Prümers et al. Lidar reveals pre-Hispanic low-density urbanism in the Bolivian Amazon. Nature. Published May 25, 2022. doi: 10.1038/s41586-022-04780-4.

amazon, lasers reveal ancient urban sprawl hidden in the amazon

About Bruce Bower

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

Keyword: Lasers reveal ancient urban sprawl hidden in the Amazon

TECH'S NEWS RELATED

Daily Crunch: Google will use private subsea cable to launch its first full-scale cloud region in Africa

The TechCrunch Top 3 Startups and VC Dear Sophie: Any tips for negotiating visa and green card sponsorship? Big Tech Inc. To get a roundup of TechCrunch’s biggest and most important stories delivered to your inbox every day at 3 p.m. PDT, subscribe here. Happy Wednesday! Haje is enjoying ...

View more: Daily Crunch: Google will use private subsea cable to launch its first full-scale cloud region in Africa

Apple Watch battery blowout sends man to emergency room

Apple Watch Series 7 AppleInsider is supported by its audience and may earn commission as an Amazon Associate and affiliate partner on qualifying purchases. These affiliate partnerships do not influence our editorial content. Over the course of an evening and night, a man’s Apple Watch battery expanded, overheated — and ...

View more: Apple Watch battery blowout sends man to emergency room

Newegg's FantasTech Sale Arrives Just In Time For Prime Day

Expect to see huge price cuts on GPUs, monitors, keyboards, and more.

View more: Newegg's FantasTech Sale Arrives Just In Time For Prime Day

The Best Xbox Series S Deal Yet Goes Live At Target Tomorrow

The impressive discount is offered as part of Target's Deal Days, and it will only stick around until October 8.

View more: The Best Xbox Series S Deal Yet Goes Live At Target Tomorrow

How to Sign Up for Amazon Prime Before Prime Day Begins

A second Amazon Prime Day is coming up next week, and a Prime membership could come in handy.

View more: How to Sign Up for Amazon Prime Before Prime Day Begins

Compared: Parallels Desktop 18 vs VMWare Fusion

Parallels Desktop for Mac VMware Fusion But what about Boot Camp? Parallels Desktop 18 for Mac VMWare Fusion Not a close race Where to buy You can get Windows onto an Apple Silicon MacBook Air. AppleInsider is supported by its audience and may earn commission as an Amazon Associate ...

View more: Compared: Parallels Desktop 18 vs VMWare Fusion

Empathizing with the opposition may make you more politically persuasive

Credit: Unsplash/CC0 Public Domain Trying to understand people we disagree with can feel like an effort hardly worth making, particularly in contentious political environments in which offering even the smallest olive branch to the opposition can be perceived as betraying our own side. Research in Psychological Science, however, suggests ...

View more: Empathizing with the opposition may make you more politically persuasive

Blast away upcoming winter grime with a 2,250 PSI $167 electric pressure washer in New Green Deals

Sun Joe’s powerful electric pressure washer hits new low ecobee thermostats learn your routine to save on heating costs from $90 refurb Jackery Explorer 2000 Pro power station and solar panel bundle hits $2,098 low (Save $700) New Tesla deals New e-bike deals + electric scooter discounts Additional New ...

View more: Blast away upcoming winter grime with a 2,250 PSI $167 electric pressure washer in New Green Deals

Usual suspects complain about App Store price hikes outside US

How to pair AirPods with Android, Windows, Nintendo Switch

Google Chrome is the most vulnerable browser in 2022

10 Best Free Image Recognition Apps for iPhone

Apple releases watchOS 9.1 developer beta 4

Get Ready for Matter With a New Smart Home Display, Speaker, or Router

Daily Deal: Save 33% on the Samsung Galaxy Buds Live

Founded by Google’s former head of ads, Neeva brings its ad-free search engine to Europe

Graphic designer’s Mac Studio rocks but ultra-wide display struggles [Setups]

Losing amphibians may be tied to spikes in human malaria cases

11:11 Systems to Acquire Recovery Business of Sungard Availability Services

Best Steam Deck SD card in 2022

OTHER TECH NEWS

;