The astonishing Nazca Lines of Peru are one of the true wonders of the ancient world. The figures they form are still visible from the air despite the passage of approximately 2,000 years of time since their original creation.
But it turns out there were many more of these figures spread out across the surface of the Nazca desert than had previously been believed. While it took nearly a century for observers to identify 430 of the larger figures, a new AI analytical program detected the faint outlines of hundreds more that human eyes had missed.
The AI system was used to scrutinized imagery collected by drones that ranged far and wide across the entire Nazca desert region, where the glyph makers were active between 200 BC and 500 AD. Its sensitivity surpasses that of the human eye by 20 times, which is why it can make out the outlines of humans and animals that have been repeatedly missed by researchers looking at aerial photographs and satellite imagery.
Drone images taken during the field survey that confirmed the geoglyphs as authentic. The scale bars are 5 m. Outlines have been added as a guide to the eye. Versions of the images without the outlines and archaeological interpretations of the relief can be found in the PNAS paper. (Sakai, M. et al./PNAS)
How Artificial Intelligence Revealed the Secrets of Nazca
The breathtaking collection of carved figures known as the Nazca Lines decorate a 170-square-mile (440-square-kilometer) patch of ground in Peru’s arid and inhospitable Nazca Desert. They were created by a pre-Inca people known as the Nazca, who made them by scraping off or digging out the upper layers of the desert’s reddened surface to reveal lighter soils hidden beneath. Using this simple methodology they were able to create figures of all shapes and sizes, which they did enthusiastically for centuries.
The AI program used to explore the lines more thoroughly was built by scientists at the IBM Thomas J Watson Research Center in Yorktown Heights, New York. The request to create it came from a team of Nazca researchers from Japan’s Yamagata University, led by archaeologist and anthropologist Masato Sakai.
There are still more geoglyph candidates identified by the AI detection system that have to be investigated. But on-the-ground surveys that took place over a six-month period in 2022 and 2023 verified the presence of 303 new geoglyphs at Nazca, increasing the known catalog of figures by 40%.
Once the other sites are looked at, researchers hope to boost this number by 200-300 more, as they now realize the ancient geoglyph makers were far more active and productive than previously believed.
What the AI system has proven to be particularly good at is spotting smaller figures that feature more intricate details.
“Even with limited training examples, the developed AI approach is demonstrated to be effective in detecting the smaller relief-type geoglyphs, which unlike the giant line-type geoglyphs are very difficult to discern,” the study authors wrote in a new article appearing in the journal PNAS. “The improved account of figurative geoglyphs enables us to analyze their motifs and distribution across the Nazca Pampa.”
Types of Glyphs
The giant figures covering the desert floor and the smaller relief figures that surround them were undoubtedly made by the same people. Nevertheless, there are clear differences between the themes explored in the two types of geoglyphs.
“We find that relief-type geoglyphs depict mainly human motifs or motifs of things modified by humans, such as domesticated animals and decapitated heads (81.6%),” the researchers wrote. “They are typically located within viewing distance (on average 43 meters) of ancient trails that crisscross the Nazca Pampa and were most likely built and viewed at the individual or small group level.”
According to the researchers, the newly discovered lines depict a wide variety of figures, including abstract human-like creatures, decapitated human heads, domesticated animals, non-domesticated animals like fish and birds, humans and animals interacting, and in one instance a carving that is said to resemble a “killer whale holding a knife.” The latter figure is one of the largest of the relief-type images, covering 72 feet (22 meters) of ground from top to bottom.
Nazca glyph likened to a killer whale holding a knife. (Sakai, M. et al./PNAS)
The location of the relief figures along trails suggests they might have been made spontaneously by travelers. In contrast, the giant figures that decorate the landscape in the Nazca desert required more planning and more coordination among a larger group of people to make.
“The giant line-type figurative geoglyphs mainly depict wild animals (64%),” the researchers noted. They concluded that their regular spacing “suggests that they were probably built and used on a community level for ritual activities.”
The giant figures were first seen from the skies by early airplane travelers in the 1920s. People have been looking for more of them ever since, and never before have so many been discovered in such a brief period of time.
Studying the World’s Most Elaborate and Expansive Ceremonial Center
Evaluating what has been discovered as a whole, the researchers from Yamagata University have drawn some conclusions about what the creation of the entire network of Nazca figures is all about.
“The reason why the purpose of the geoglyphs’ creation remained unknown for so long is that previous researchers lacked basic information about the distribution and types of geoglyphs,” Masato Sakai told ScienceAlert. “However, in this paper, thanks to field surveys utilizing AI and remote sensing, the distribution of the geoglyphs has been clarified. As a result, we were able to shed light on the purpose behind their creation.”
That purpose, they say, is to draw visitors to the spiritual and ceremonial center of Nazca culture, which was known as Cahuachi. This complex of adobe structures overlooks some of the figures from perches built on mounds, allowing for a spectacular view of the surrounding landscape.
Here there was a complex network of interconnected geoglyphs of different sizes, which Sakai maintains “is connected to ceremonial centers [like] Cahuachi and sacred places.”
“In the ancient Andean civilization, socially important information was sometimes conveyed through combinations and arrangements of pictures,” he continued. “I believe that information was inscribed on the Nazca Pampa through the arrangement and combination of geoglyphs.”
Decoding that information remains an ongoing challenge, Sakai acknowledges. But now that so many previously hidden Nazca figures have been discovered, interpreting the true meaning of all of them could be easier—if such a thing can actually be done.
Top image: Six of a total of 303 newly discovered relief-type figurative geoglyphs from the AI-assisted survey. Source: Sakai, M. et al./PNAS