Lovely place for a stopover (Image: R Mcleod/Robert Harding/Rex)

The heart of the Atacama desert is the driest place on Earth. But that didn’t prevent the first settlers of South America from setting up home there more than 12,000 years ago.

Aside from Antarctica, South America was the last continent that modern humans colonised, says Claudio Latorre of the Pontifical Catholic University of Chile in Santiago. The first settlers arrived from North America at least 14,000 years ago, but their route south is a mystery. Most researchers assume they travelled through fertile corridors, perhaps down the west coast where seafood was plentiful, at least until you hit the desert.

“Extreme environments, such as the Atacama, were naturally assumed to be barriers,” says Latorre. “This was not the case.”


Atacama life

Latorre and colleagues excavated a site called Quebrada Maní, which lies 85 kilometres inland and only receives rain a few times a century.

Digging on a low hill surrounded by arid valleys, they found stone tools, animal bones, sea shells and the remains of a fireplace.

How did these people survive in the Atacama? Most of the desert’s core was just as harsh then as it is today. But the team found the remains of plants at the site, suggesting that the valleys had seasonal marshes that acted as oases, and which have since dried up. Nowadays, only a few hardy microbes live there, often underground.

Oasis hopping

If people did enter South America along its west coast, Quebrada Maní could have been an important pit stop for heading inland, says team member Calogero Santoro of the University of Tarapacá in Arica, Chile. “Certain features of the site seem to correspond to a base camp,” he says.

“We need to think in terms of oasis hopping,” agrees Silvia Gonzalez of Liverpool John Moores University in the UK. She has found similar archaeological sites in Mexican deserts where there were once oases. “These barren sites were not barren then.”

If the settlers really were journeying between widely separated oases, they must have been skilled navigators. Gonzalez thinks their society was probably already quite sophisticated. “Even at this early stage, there was probably trade,” she says, with distant settlements exchanging items like sea shells and volcanic glass.

Journal reference: Quaternary Science Reviews, DOI: 10.1016/j.quascirev.2013.06.008