- By looking at satellite images of a previously unexplored part of the Amazon in the Brazilian state of Mato Grosso, a team of archaeologists has identified 81 pre-Columbian human settlements.
- The team also found that the settlements weren’t near major rivers, but closer to smaller streams and creeks, challenging a commonly held belief that pre-Columbian people tended to live close to fertile floodplains of large rivers, leaving the rest of the forest relatively untouched.
- The researchers’ computer model predicted that the southern rim of the Amazon likely supported up to 1 million people in pre-Columbian times, a population that’s much larger than previous estimates.
Archaeologists have over the past few decades uncovered a growing body of evidence suggesting the pre-Columbian Amazon was not the sparsely populated, pristine rainforest it was widely believed to have been.
Now, new research adds to this evidence.
By looking at satellite images of a previously unexplored part of the Amazon in the Brazilian state of Mato Grosso, a team of archaeologists have identified 81 human settlements that pre-date the arrival of the Europeans. At all these sites, the team could see the remains of fortified villages and geoglyphs, human-made earthworks in square, circular or hexagonal form, likely used for ceremonies.
The archaeologists also checked 24 of these sites on the ground, and confirmed that those were indeed real archaeological sites, “representative of the region as a whole.”
In fact, on investigating one site in detail, the team discovered fragments of ceramics, polished stone axes and soil rich in charcoal — indications of long-term human habitation. They dated these to between A.D. 1410 and 1460, the researchers report in the study published in Nature Communications.
The team also found that the settlements weren’t near major rivers, but closer to smaller streams and creeks. This challenges a commonly held belief that pre-Columbian people tended to live close to fertile floodplains of large rivers, leaving the rest of the forest relatively untouched.
“The idea was that in the areas that are located further away from the main rivers, populations maybe were actually smaller and they had a negligible impact on the environment,” lead author, Jonas Gregorio de Souza of the University of Exeter, U.K., told The Guardian. “We demonstrated that these regions may have had pretty large populations as well in the past.”
The researchers’ computer model predicted that similar settlements could have occurred over 400,000 square kilometers (154,000 square miles) of the southern rim of the Amazon in pre-Columbian times. This region alone, representing about 7 percent of the Amazon, could have supported a population of 500,000 to 1 million people, the researchers estimate, challenging previous low estimates of up to 2 million people for the entire Amazon basin.
This doesn’t mean that the entire Amazon was densely populated, though. Further exploration of the previously uncharted Amazonian regions is necessary to figure out how the pre-Columbian communities were distributed, the researchers say.
“Most of the Amazon hasn’t been excavated yet, but studies such as ours mean we are gradually piecing together more and more information about the history of the largest rainforest on the planet,” José Iriarte, also of the University of Exeter, said in a statement. “Our research shows we need to re-evaluate the history of the Amazon. It certainly wasn’t an area populated only near the banks of large rivers, and the people who lived there did change the landscape. The area we surveyed had a population of at least tens of thousands.”
- De Souza, J.G., et al (2018). Pre-Columbian earth-builders settled along the entire southern rim of the Amazon. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03510-7