Colossal rock engravings may be ancient borders, study suggests

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Ancient rock engravings in what’s now South America — believed to be among the largest in the world — were meant to mark the boundaries of the territories inhabited by their makers, according to a new study.

Birds, Amazonian centipedes, human figures and geometric shapes are among the designs, found across 14 sites — most already known, but some newly discovered — along a 60-mile (97-kilometer) stretch of the Orinoco River, in present-day Venezuela and Colombia.

However, the most represented motif is gigantic snakes, and one in particular — in a site called Cerro Pintado in Venezuela — at about 138 feet (42 meters) in length is likely the single largest rock engraving recorded anywhere in the world, the researchers suggested.

“There are two sides to these being territorial markers,” said Dr. Philip Riris, lead author of the study published Monday in the journal Antiquity. “One could be a warning sign — you’re in our backyard, you better behave yourself. The other could be a marker of identity — you’re in our backyard, you’re among friends. But I don’t think they had a single purpose, so they could easily be both.”

Snake mythology

The study focuses on the meaning and the role played by the snakes in the mythology of the indigenous people of the area, said Riris, a senior lecturer in archaeological environmental modeling at Bournemouth University in the United Kingdom. He believes local inhabitants likely carved the rocks between 1,000 and 2,000 years ago, based on pottery and motifs from that time frame found in the same area.

“Snakes are really interesting, because they’re both creators and protectors. According to local mythology, they shaped the rivers as they traveled, however they’re also predators, full of dangerous energies that you need to respect in order not to fall afoul of their wrath,” Riris said, explaining why they could also have a dual meaning as rock carvings.

All of the snake designs share a visual consistency, and Riris believes they could represent boa constrictors or anacondas, although the artists weren’t necessarily interested in accurately representing certain species: “Indigenous people don’t always distinguish species in the same way that we do in scientific taxonomy — they could just be large, predatory snakes that kill by constricting,” he said.

Human figures are often depicted alongside the snakes, as are giant Amazonian centipedes, which are predatory toward snakes in the Orinoco. The geometric designs include concentric circles, spirals and rectangles, but their meaning isn’t quite clear, according to Riris.

The use of such ancient monumental markings as territorial markers has been observed before, but the Orinoco engravings stand out, Riris noted.

“What makes the Orinoco special is just how large they are, the sheer quantity and density, and what lengths their creators had to go to make them,” he said. Some of the rock formations on which they are carved are “perilous,” Riris added, noting that the artists may have had to use ropes or ladders to reach them.

Monumental rock art of a snake tail in Colombia dwarfs the humans in this image. - Philip Riris et al.
Monumental rock art of a snake tail in Colombia dwarfs the humans in this image. - Philip Riris et al.

Indigenous custodians

The study is the result of data collected during 10 years of field work by Riris and his colleagues — coauthors Dr. José Oliver and Natalia Lozada Mendieta — although some of the research was used for other studies. Oliver is a reader in Latin American archaeology at the University College London and Lozada Mendieta is an assistant professor of art history at Universidad de Los Andes in Colombia.

The markings are located in a section of the river called the Atures Rapids, known to have been an important trade and travel route in prehistoric times. The team used special software to recreate the viewpoint of ancient dwellers and visualize how the markings would have appeared to them.

Today, with tourism fast rising, the sites could be at risk of vandalism, and the researchers registered them with Colombian and Venezuelan national heritage bodies.

“Luckily, to our knowledge none of them have been damaged, but with more people around they’re more exposed,” Riris said, adding that both authorities and indigenous people, who feel a sense of ownership over them, need to be involved in their safeguarding.

A close-up shows a detail of rock art on Picure Island, Venezuela. - Philip Riris et al.
A close-up shows a detail of rock art on Picure Island, Venezuela. - Philip Riris et al.

The ancient works give us a rare glimpse into how native groups of the Orinoco perceived their landscape and made it sacred and instrumental through rock engravings, said George Lau, a professor of art and archaeology of the Americas at the University of East Anglia in the UK. He was not involved with the study.

“It also shows the long-term resilience of such art for native landscapes, especially the importance of mythic creatures to local belief systems. The study really is only the tip of the iceberg for the enormously rich archaeology and ancient cultures of this region,” he added.

According to Dr. Alexander Geurds, an associate professor in Middle and South American archaeology at the University of Oxford in the UK, this research is a key contribution to the understanding of rock art in northern South America. He was also not involved with the work.

The study goes beyond earlier work, Geurds said, because it doesn’t simply record the location and style of the carved depictions, but also deals with their extraordinary size. Applying computer-based visual analysis is an innovative step, he added, as it helps understand how the scale of the carving relates to the possibility to spot these from far away — a likely scenario if indigenous groups traveled along the Orinoco River.

Part of the key importance of these large-scale carvings is the collective labor they required: “Especially at larger rivers and river junctions, these could have been spots where people came together to forge intercommunity ties during late pre-Hispanic times,” Geurds said. “Also, rapids are (ironically) where canoe traffic slows down, allowing for a suitable theater to behold the images. These monumental snakes are silent witnesses to this past social world.”

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