Human Burials Reveal Settlements in Bolivia 10,000 Years Ago

La Chacra forest island, Llanos de Moxos
La Chacra forest island in the Bolivian Llanos de Moxos. One of the sites where archaeological excavations revealed the existence of Early and Middle Holocene human occupations including burials. José Capriles, PSU

Humans settled in the South American region of southwestern Amazonia, and even experimented with agriculture there, far earlier than previously thought, according to an international team of researchers.

Around 2,500 years ago—long before the European conquest of the continent—complex societies practicing hunting, gathering, fishing and intensive agriculture began to emerge in the Amazonian tropics.

We know that these societies had a significant impact on their local environment through such practices, as well as through the construction of ceremonial structures and roads. However, our understanding of the people who came before them—the communities that initiated the process of plant domestication—is limited, in part because the tropical landscape did not always preserve their traces.

Now, researchers have cast new light on this period in a study published in the journal Science Advances. The researchers found evidence to suggest that hunter-gatherers in Llanos de Moxos—an ecoregion in northern Bolivia, southwestern Amazonia—were living in persistent settlements that transformed the landscape as early as 10,000 years ago, long before the emergence of later agriculture intensive societies.

For their study, the researchers—led by Pennsylvania State University anthropologist José Capriles—investigated several sites containing ancient trash deposits and human burials, providing new insights into an important social and environmental transition in the region.

"Because the region is devoid of stone, we did not have much information about the nature of human occupation before ceramic-producing agricultural societies," Capriles told Newsweek. "The finding of these sites extends by several millennia the history of human occupation of southwestern Amazonia."

"This is important because, according to genetic and botanical research, this region has been identified as the probable place of domestication for plants such as cassava, sweet potatoes, peanuts and species of chili peppers," he said.

The team's analysis indicated that the sites in Llanos de Moxos were at the center of stable, persistent communities with intensive resource use and increasingly defined territories between around 10,600 and 4,000 years ago.

"These sites are circular forest islands surrounded by grassland savanna in the seasonally flooded Llanos de Moxos," Capriles said. "They are relatively small, less than a hectare in surface and are slightly higher than the surrounding savanna. They were made by overlapping layers of human activities, including abundant remains of trash consisting of burned earth, freshwater apple snails, charcoal and animal bones. Within these layers, we found human burials."

According to the study, these archaeological sites represent the earliest evidence of communities in the Amazonian tropical lowlands beginning the transition toward full-scale intensive agriculture.

"The presence of these sites and the composition suggest that these societies were engaged in hunting, fishing, and gathering consistent with disturbance and resource depression that might have generated the incentives for experimenting with agriculture," Capriles said.

The researchers say that we are only just beginning to understand the basic aspects of the economic, social and political organization of these societies.

"However, similar to many modern ethnographically documented Amazonian societies, they seemed to have been intrinsically connected with their resources and likely manufactured most of their material culture from organic materials," Capriles said.

"These were likely egalitarian hunter-gatherers who were seasonally tethered to these sites most likely because of the seasonal flooding," he said. "In this sense they practiced adaptive strategies similar to those documented by groups such as the Sirionó, who were still practicing residential mobility in this region less than a century ago."

Despite the intriguing new findings, Capriles said that a significant gap still exists in our knowledge between the people who lived on the forest islands between 10,000 and 4,000 years ago, and the rise of complex societies about 2,500 years ago.

"Are the people we found direct predecessors of those later, more complex societies? There are still questions to be answered and we hope to do so in future research," he said in a statement.

This article was updated to include additional comments from José Capriles.