Satellite images have revealed an ancient system of elaborate, funnel-shaped mega traps likely built by hunters and pastoralists to catch prey in the high altitudes of northern Chile.
New research on the Andean landscape and the people who lived there has identified 76 stone 'chacus', often stretching hundreds of metres in length, that would have been used to capture vicuña, a wild relative of the alpaca.
Similar structures have been found in other arid regions of the world, including the Middle East, but this is the first time such a concentration has been discovered in the area, and it raises the possibility that they pre-date those known to have been used by the Inkas.
An archaeologist at the University of Exeter has also found evidence of settlements and outposts in the area known as the Western Valleys, establishing a high probability that it was home to foragers many centuries after it was believed people had adopted more settled agricultural social systems.
The study, by Dr Adrián Oyaneder, of Exeter's Department of Archaeology and History, is published in the journal Antiquity, and is based on the research he conducted during his PhD.
"There has long been a discrepancy between what archaeological and ethnohistorical records have told us about life in the Western Valleys of northern Chile during the colonial period," says Dr Oyaneder. "On the one hand, archaeological research has pointed to a gradual decline in hunting and gathering from 2,000 B.C. onwards with the introduction of domesticated plants and animals. But, historical sources, such as Spanish tax records from the 16th to the 19th centuries, refer to 'Uru' or 'Uro', which was a generic term for foraging populations who were of little economic interest to the colonisers."
Using publicly available satellite data, Dr Oyaneder examined a 4,600 square-kilometre area of the Camarones River Basin, focusing on upland areas that had hitherto remained little studied. Over four months, he identified a huge number of new sites of archaeological interest.
Among them were 76 chacus, with the great majority being V-shaped traps formed by two 'antennae' built from dry-stone walls, around 1.5 metres in height and on average 150 metres in length. These funnelled down to an enclosure of around 95 square metres, which would have been dug or established to a depth of around two metres, sufficient to trap any animals driven into it by the hunters.
All the chacus were located on steep slopes, pointing downhill, with some employing natural topographical features to create one of the antennae. They were also at an altitude within the usual range of the vicuña.
"My reaction when I saw the first chacu was to double and even triple check it," said Dr Oyaneder. "Initially, I thought it was a bit of a unique occurrence, but as I progressed with my survey, I realised that they were everywhere in the highlands and in a quantity never previously recorded in the Andes.
"And then when I began to read papers and books around the subject, particularly by Thérèse Bouysse-Cassagne and Olivia Harris, there was reference to the choquela, specialised vicuña hunting groups, and words referring specifically to chacu hunting people and chacu hunters."
Dr Oyaneder identified almost 800 small-scale settlements, ranging from single buildings of no more than one square metre to groups of nine or more structures. These were plotted using GIS and grouped into likely clusters linked to nearby chacus and other settlements, all within a 5km distance.
"The picture that emerges is of a landscape occupied by a range of human groups from at least 6000 B.C. to the 18th century," adds Dr Oyaneder. "These groups moved strategically across the highlands, tethered primarily to hunting resources, particularly vicuña. The evidence indicates overlapping lifeways, combining hunting-gathering with agropastoral practices, and a network of short-term seasonal settlements and outposts to help people move across rugged and difficult terrain."
Dr Oyaneder is now conducting further research to date some of these sites and establish whether they represent the first examples of their kind in the Andean region.
