Early human settlements in Amazonia predate the first complex societies

The discovery of human skeletons excavated from archeological sites in northern Bolivia suggests that humans settled in southwestern Amazonia thousands of years before the formation of complex societies.

Archeologists from Pennsylvania State University, along with an international team of researchers, unearthed the fossilized remains while surveying three forest islands, Isla del Tesoro, La Chacra and San Pablo, in northern Bolivia.

“These islands are elevated above the surrounding savanna, so they do not flood during the rainy season,” said Jose Capriles, an Assistant Professor of Anthropology. “We believe people were using these sites recurrently as seasonal camps, particularly during the long rainy seasons when most of the Llanos de Moxos become flooded.”

The first complex societies in the region formed around 2,500 years ago but researchers know very little about the people that passed through the area in the early Holocene thousands of years prior.

In this new study, the researchers theorize that humans settled and even attempted early agriculture in southwestern Amazonia up to 10,000 years ago, much earlier than previously thought.

“These groups of people were hunter-gatherers; however, our data show that they were beginning to deplete their local resources and establish territorial behaviors, perhaps driving them to begin domesticating plants such as sweet potatoes, cassava, peanuts, and chili peppers as a way to acquire food,” said Capriles.

When the skeletons were first discovered, the way the remains were placed in the ground pointed to an intentional burial which would have been out of character for typical hunter-gathers in the region.

Instead, the intentional burial is evidence of a more permanent early human settlement.

“If these were highly mobile hunter-gatherers you would not expect for them to bury their dead in specific places; instead, they would leave their dead wherever they died,” said Capriles.

It is rare to find human or archeological remains from the early Holocene in this region, according to the researchers, making the find all the more noteworthy.

An earlier study detailing the discovery in 2013 was very limited in its findings because there was very little to go off that could help date the remains or shed light on what sort of people inhabited the area at the time.

“Because of the lack of direct evidence many archaeologists were skeptical about our findings,” said Umberto Lombardo, an author of the 2013 study. “They did not really believe that those forest islands were early Holocene archaeological sites. The current study provides strong and definitive evidence of the anthropocentric origin of these sites, because the archaeological excavations uncovered early Holocene human burials. These are the definitive proof of the antiquity and origin of these sites.”

The researchers carbon-dated charcoal and shells that were buried along with remains to provide a more accurate time period for when the area was first inhabited and settled.

The results of the carbon dating indicate that people were living, foraging, and burning fires on the islands between 10,000 and 4,000 years ago.

“This paper represents the first step in the effort to learn more about the people who inhabited southwestern Amazonia for thousands of years, but we know nothing about,” said Lombardo.

The new study was published in the journal Science Advances.

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By Kay Vandette, Earth.com Staff Writer