Scientists document highest altitude ice age human occupation

Scientists have documented the highest altitude ice age human occupation anywhere in the world — nearly 4,500 meters above sea level in the southern Peruvian Andes. 
The discovery by researchers at the University of Maine date high-altitude human habitation nearly a millennium earlier than previously documented.
Despite cold temperatures, high solar radiation and low oxygen conditions at that altitude, hunter-gatherers colonized the remote, treeless landscapes about 12,000 years ago during the terminal Pleistocene — within 2,000 years after humans arrived in South America. 

The findings from the sites in the Pucuncho Basin have been co-authored by a team of researchers including University of Calgary archaeologist Sonia Zarrillo. 

The primary site Cuncaicha is a rock shelter with a stone-tool workshop below it. 

The researchers said "Climatic conditions in both sites are harsh, with factors including low-oxygen, extreme cold and high levels of solar radiation making life in the region a challenge for any humans. And yet, the findings indicate that people were living in these high altitude zones for extended periods of time. Cuncaicha was occupied about 12.4 to 11.5 thousand years ago while the Pucuncho workshop site dates to around 12.8 to 11.5 thousand years ago." 

"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," says Zarrillo. "There were possibly even families living at these sites, because we've found evidence of a whole range of activities." 

Archaeological evidence found at Cuncaicha includes signs of habitation such as human skull fragments, animal remains and stone tools. 

"Hunters passing through an area will take the meat back to campsites and leave the carcass in the field," says Zarrillo. "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." 

The Pucuncho archaeological site included 260 formal tools, such as projectile points, nondiagnostic bifaces and unifacial scrapers up to 12,800 years old. 

Cuncaicha rockshelter, featuring two alcoves contained a "robust, well-preserved and well-dated occupation sequence" up to 12,400 years old. The rockshelter, with views of wetland and grassland habitats, features sooted ceilings and rock art, and was likely a base camp. 

Most of the lithic tools at Cuncaicha were made from locally available obsidian, andesite and jasper, and are indicative of hunting and butchering consistent with limited subsistence options on the plateau, according to the researchers. In addition to plant remains, bones at the site indicate hunting of vicuna and guanaco camelids and the taruca deer. 

It is unclear whether the high-altitude human settlement required genetic or environmental adaptations. But with evidence of high-altitude human habitation almost 900 years earlier than previously documented, the implication is that there may have been more moderate late-glacial Andean environments and greater physiological capabilities for Pleistocene humans. 

A popular scientific theory about high altitude colonization suggests that people cannot live in high altitudes until genetic adaptation occurs, like the sort we find in Andean people today. Andeans have genetically adapted to their high altitude environment, Zarrillo notes. 

Key differences in the Andean people include a higher metabolic rate, larger lung capacity and higher haemoglobin concentrations then the average person, all of which allow them to overcome a lack of oxygen.

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