“Most of the Amazon is still unexplored archaeologically,” says Jonas De Souza of the University of Exeter, UK. “The more we survey, the more we realise that different parts of the basin were more settled than we thought.”

The first Europeans to travel to the Amazon reported seeing widespread settlements, including cities and roads. But their reports were later dismissed as fantasies. For centuries, the prevailing view of the Amazon was that it was largely a pristine wilderness before Columbus and other Europeans arrived. Supposedly, only around a million people lived in the entire Amazon basin.

In recent decades, deforestation has helped reveal evidence of extensive ancient settlements, such as large earthworks. It now appears the whole river basin was home to perhaps ten million people before Europeans arrived. Disease and genocide later wiped most of them out, and the rainforest hid the evidence. “We have changed our idea about the Amazon,” says De Souza.

However, so far almost all the evidence of past habitation has been found on the fertile floodplains besides major rivers. Only scattered sites have been found higher up in the basin in the areas that do not flood regularly, known as terra firme.

José Iriarte

So De Souza and colleagues decided to take a look at an area of terra firme in the Tapajós river basin in Mato Grosso state in Brazil, nearly 2000 kilometres upstream from the mouth of the Amazon. There are archaeological sites to the east and west of this area, but none were known in the area.

By scouring satellite images, the team identified 81 Pre-Columbian sites, ranging from single hamlets to large fortified villages and roads. The largest site extended over an area of 20 hectares. The team visited 24 of the sites to confirm they were indeed Pre-Columbian. They are excavating one site, which dates to between 1410 and 1460.

The findings suggest that there were settlements right across a broad swathe of the southern Amazon. There was a shared tradition of building earthworks, but there are lots of local differences, says De Souza, so they were probably built by many different cultures. In one place, the local people appear to be descendants of those who built nearby Pre-Columbian earthworks, but most indigenous peoples have been displaced.

The findings add to the evidence that the Amazon was far more densely peopled than long thought. “We cannot say the whole Amazon was densely settled, but some areas were,” says De Souza.

The Pre-Columbian communities farmed in a less destructive way than modern farmers. They did clear some areas by slashing-and-burning to grow crops, but also planted lots of fruit and nut trees. In 2017 it was reported that these trees are still abundant around archaeological sites today.

“The southern and southeastern borders of Amazonia are the areas where I found the highest richness of domesticated species in the forests,” says Carolina Levis of the National Institute of Amazonian Research (INPA) in Manaus, Brazil. “Our maps match pretty well.”

Source: New Scientist