At two sites high in the southern Peruvian Andes, scientists have discovered remains that suggest human settlement about 12,000 years ago. More than 4,000 meters above sea level, they are now the highest sites for continuous human occupation ever recorded, predating the earliest known settlements by almost 900 years.
     Led by Kurt Rademaker, a University of Maine (USA) visiting assistant professor in anthropology, the team investigated one site that yielded 260 stone tools such as projectile points, bifaces and scrapers, as much as 12,800 years old. The other site, the Cuncaicha rock shelter, contained stone tools made from locally available obsidian, andesite and jasper, as well as plant remains, bones of llama-like vicunya and guanaco, and the taruca deer, and featured sooted ceilings and rock art, indicating it was likely a base camp.
     The Cuncaicha cave shelter was big enough to fit 20 or 30 people and had been occupied multiple times over thousands of years. The site is more than 2,000 metres higher than the famous Inca archeological site Machu Picchu, and just 880 metres lower than the Mount Everest base camp in the Himalayas.
     "We don't know if people were living there year round, but we strongly suspect they were not just going there to hunt for a few days," says archaeologist and research team member Sonia Zarrillo of the University of Calgary. "There were possibly even families living at these sites, because we've found evidence of a whole range of activities. In Cuncaicha we found remains representing whole animals, indicating they were living close to where the animals were killed. And the types of stone tools we've found are not only hunting tools but also scraping tools used for processing hides to make things like clothing, bags or blankets."
     Zarrillo specialises in identifying edible plants at archeological sites. There are no edible plants growing in the area surrounding the cave, yet Zarrillo found bits of edible roots and tubers from lower elevations, suggesting the cave dwellers were either trading with other groups, or at times moving to lower elevations.
     Rademaker stumbled upon the cave a few years ago while trying to locate the source of obsidian found at archeological sites on the Peruvian coast, and "instantly recognised that it was an archeological site."
     The cave is located in a cold and dry area of the Andes that Zarrillo describes as "a moonscape," but the nearby Pucuncho Basin appears to have been a rich hunting ground 12,000 years ago, when the climate was just a little bit cooler and wetter. Today, the area is used by local Andean herders to graze thousands of llamas and alpacas. The locals have genetic adaptations that allow them to live comfortably at high altitude, such as unusually large lung capacities, high metabolic rates and the ability to carry more oxygen in their blood. Those adaptations were thought to have taken thousands of years to evolve.
     The fact that humans were living at these altitudes for long periods of time just 2,000 years after entering South America raises scientific questions. In addition, Zarrillo said, it's possible that there are even older settlements in deeper layers of the cave floor or other sites in the area.

Edited from Popular Archaeology, CBC News (23 October 2014)