viernes, 24 de octubre de 2014

High altitude Pleistocene sites identified in the Peruvian Andes (Peru)

Research conducted at the highest-altitude Pleistocene archaeological sites yet identified in the world sheds new light on the capacity of humans to survive in extreme environments.
The findings, published in the journal Science were taken from sites in the Pucuncho Basin, located in the Southern Peruvian Andes. This discovery dates high-altitude human habitation to nearly a millennium earlier than previously documented, and was led by Kurt Rademaker, a University of Maine visiting assistant professor in anthropology.

Stone tools

The primary site, Cuncaicha is a rock shelter at 4,480 metres above sea level, with a stone-tool workshop below it. The rockshelter, with views of wetland and grassland habitats, features sooted ceilings and rock art, and the researchers think this was likely a base camp. It consists of two alcoves and contains a “robust, well-preserved and well-dated occupation sequence” up to 12,400 years old. 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. In addition to plant remains, bones at the site indicate hunting of vicuña and guanaco camelids and the taruca deer. There is also a Pucuncho workshop site where stone tools including 260 formal tools, such as projectile points, non-diagnostic bifaces and unifacial scrapers were made at 4,355 metres above sea level.
Pucuncho Basin was a high-altitude oasis for specialised hunting, particularly of vicuña, and later, herding of domesticated alpacas and llamas. While the Pucuncho Basin could have sustained year-round residence, wet-season storms and the dangers of hypothermia, as well as the need to maintain extended social networks and collection of edible plants, may have encouraged regular descents, according to the research team.
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 University of Calgary archaeologist Sonia Zarrillo and one of the co-authors of the study. “There were possibly even families living at these sites, because we’ve found evidence of a whole range of activities.”

Signs of habitation

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.”

High altitude living

A popular scientific theory about high altitude colonisation 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.
“Was this adaptation present 12,400 years ago? We don’t know for certain,” says Zarrillo. “What we’re demonstrating is that these people either already developed that adaptation, or, it was possible for them to live in these altitudes for extended periods of time regardless. Finding this out is one of the goals of our future research.” Zarrillo believes that other sites in the region have the potential for further ground breaking revelations, in part because they’re incredibly well preserved.
“Research really hasn’t been done here up until now, because it’s so remote,” she says. “Our team hiked up to three or four hours to get to these sites. That was a climb, carrying all of our gear, camp equipment and food. And it freezes every night. Sometimes it snows. These are incredibly hard sites to access.”

Source: Past Horizons:

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