Excavations show hunter-gatherers lived in the Amazon more than 10,000 years ago

Hunter-gatherers occupied the southwestern Amazon rainforest by around 10,600 years ago — at least several thousand years earlier than previously thought.

Excavated food remains and human burials at several locations in Bolivia support a scenario in which hunter-gatherers regularly occupied those spots for large parts of the year. The unearthed evidence also indicates that the hunter-gatherers were living in the southwestern Amazon until around 4,000 years ago, anthropological archaeologist José Capriles of Penn State University and colleagues report online April 24 in Science Advances.

If hunter-gatherers developed a preference for living in one place for months at a time, that may have led to the rise of farming societies in the southwestern Amazon around 2,500 years ago, the scientists speculate.

Capriles’ team focused on three small, forested mounds of earth located in dry grasslands that flood during rainy months. The researchers uncovered deposits of burned clay and wood bits likely produced by fireplaces of some kind, snail shells and bones of fish and small mammals. Skeletons of five people buried at the three sites were also found. Radiocarbon dating places the ages of these graves at around 6,250 years old or more.

As a drier climate took hold between roughly 8,000 and 5,500 years ago, hunter-gatherers in the southwestern Amazon may have intensified their occupations of campsites near patchy, seasonal wetlands for part of the year. By interring some of their dead at those sites, foraging communities may have claimed that valuable property and nearby wetland resources as theirs, the team suspects.