WASHINGTON – In a bleak, treeless landscape high in the southern Peruvian Andes, bands of intrepid Ice Age people hunkered down in rudimentary dwellings and withstood frigid weather, thin air and other hardships.
Scientists on Thursday described the world’s highest known Ice Age settlements, two archaeological sites about 2.8 miles (4.5 km) above sea level and about 12,000 years old packed with artifacts including a rock shelter, stone tools, animal bones, food remnants and primitive artwork.
“What this tells us is that hunter-gatherers were capable of colonizing a very extreme environment, the high Andes, despite the challenges at the end of the Ice Age,” said archaeologist Kurt Rademaker of Germany’s University of Tuebingen, who led the study published in the journal Science.
“And they did so quite successfully. It pushes back the date of initial entry of humans to this kind of elevation.”
The sites in an Andean locale called the Pucuncho Basin were occupied by small numbers of people, probably only in the dozens.
“Bands of hunter-gatherers are small and not many could fit into the rock shelter, perhaps just a few families,” said University of Maine archaeologist Dan Sandweiss, another of the researchers.
The researchers said the sites show high-altitude human habitation was occurring nearly a millennium earlier than previously known.
“We look at the challenges and we say, ‘Why would you do that when you could just live somewhere else?’ ” Rademaker said. “Whatever reason they initially went up there, there were reasons to stay despite the challenges.”
At that altitude, temperatures averaged 37 degrees Fahrenheit (3 degrees Celsius), solar radiation was high and oxygen was low. But there also were animals like vicuna and guanaco — llama relatives — and taruca deer to hunt, the rock shelter, water in streams, bogs and wetlands, and stone like obsidian to make tools.
The tools included spear points, scrapers for working animal hides and implements for cutting and butchering. “A lot of the stone tools seem to be all about hunting and processing of animals,” Rademaker said.
The ceilings of the natural rock shelters were blackened with soot from fires. The researchers found an abundance of animal bones as well as potatolike starchy tubers that apparently were gathered from lower elevations.
There also was art on the walls of the rock shelters including red ochre pictographs of animals, with some entire wall sections painted red.
“We don’t know whether they date back to the earliest occupation of the site,” Rademaker said.
An open-air site called Pucuncho 14,300 feet (4,355 meters) above sea level yielded hundreds of tools. The Cuncaicha rock shelter featured two alcoves and likely served as a base camp at 14,700 feet (4,480 meters).
Some experts think people need to acquire genetic adaptations over many thousands of years to withstand such altitudes. But the fact that people colonized these sites only about 2,000 years after humans first entered South America may suggest otherwise.
“We have to re-examine that idea,” Rademaker said.