Working in the southern Peruvian Andes about 4,500 meters above sea level, researchers have uncovered the oldest, extreme altitude human settlements in the Americas. The two hunter-gatherer sites—a base camp and a workshop—are the highest Ice Age human habitats known in the world. The findings, published in Science this week, suggests that humans adapted to high-elevation environments a millennium earlier than we thought.
How humans settled in potentially hazardous areas with low oxygen, high solar radiation, and freezing temperatures is poorly understood. Some say glaciers had to recede to create an opening for humans to migrate through. Others say it took many thousands of years for humans to become genetically capable: high metabolic rates, large lung capacities, and higher hemoglobin concentrations would certainly help. But now, researchers have found a few hundred Pleistocene stone artifacts 900 meters above the highest-known archaeological site so far—which just goes to show, “people were more capable than we thought they were,” Kurt Rademaker from the University of Maine tells Science.
The Cuncaicha site (4,480 meters above sea level) features a robust rock shelter and dates back to between 11,500 and 12,400 years. Boasting views of wetland and grassland habitats, sooted ceilings, and rock art, the site was likely a base camp. Here, the team found roots for eating, butchered animal bones belonging to vicuñas (a llama relative), guanaco camelids, and taruca deer, as well as stone tools made from locally available obsidian, andesite, and jasper.
The second site at Pucuncho Basin (4,355 meters above sea level) was a stone tool workshop that specialized in hunting vicuña, and later, herding alpacas and llamas. The team found 260 tools including fishtail projectile points dated between 11,500 and 12,800 years. The tools and debris included nonlocal, fine-grained, and even stream-polished rocks, which would have required plateau residents to visit high-energy rivers at lower elevations. Here are some vicuñas in the treeless Pucuncho Basin:
"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, then leaving," University of Calgary’s Sonia Zarrillo says in a news release. Hunters simply passing through will typically leave the carcass in the field, but remains representing whole animals at the site suggests that they live 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 adds. The range of activities suggests that families might have been living at these sites. However, wet-season storms, hypothermia, and the need to maintain social networks and edible plants likely encouraged regular descents, the authors say in a statement.
The findings suggest humans colonized the region within just 2,000 years of our first entry into South America. That means a lengthy period of adaptation wasn’t required for acclimation. Furthermore, because glaciers in the region never actually reached Pucuncho Basin, they never receded and created an opening. But humans migrated and moved upwards anyway, suggesting genetic and environmental changes weren’t required for successful colonization.
Images: Kurt Rademaker
