Artificial Intelligence Helped Discover 300 New Geoglyphs in the Nazca Desert

Using an artificial intelligence (AI) system, a team of archaeologists has discovered in just a few months in the Nazca Desert (Peru) almost as many geoglyphs as were found in the entire last century. The large number of new figures allowed the researchers to identify two main types and offer an explanation for the possible reasons or functions that prompted their creators to draw them on the ground more than 2,000 years ago.

The Nazca Desert, with a total area of almost 500 km² and an average altitude of 500 meters above sea level, is distinguished by special climatic conditions. It almost never rains here, the hot air blocks the wind, and the dry land prevents the development of agriculture and livestock farming. All this together has allowed a number of lines and figures formed by laying and leveling pebbles and stones to be preserved over the centuries.

The first layer of soil is a blanket of small reddish stones, which when lifted reveal a second, yellowish layer. This difference in color is the basis of the geoglyphs, and it was this that the ancient Nazca civilization used to create them. Some of them are straight lines that stretch for several miles. Others are geometric figures or rectilinear figures, also of enormous size. Another main category is the so-called relief-type geoglyphs, which are smaller in size.

In the 1930s, Peruvian aviators discovered the first of them, and by the end of the century, more than a hundred had been identified, including a hummingbird, a frog, and a whale. Since 2004, Japanese archaeologists have found 318 more geoglyphs, almost all of them well-known, thanks to high-resolution satellite images. The same team, led by Masato Sakai, a scientist at Yamagata University in Japan, found 303 new geoglyphs in just one campaign, using artificial intelligence.

“These technologies speed up the process,” Sakai admits when asked about the benefits of artificial intelligence. “The Nazca Pampas are a huge area of over 400 square kilometers, and they haven’t been studied in any detail,” the Japanese scientist recalls. Only the northern part, where the large linear geoglyphs are concentrated, “has been studied relatively intensively,” he adds. “But throughout the rest of the desert, there are many relief figures that are smaller in size and have become more difficult to detect over time.”

Convinced there were many more, Sakai and his team turned to IBM’s AI division, where Watson was created. They had high-resolution images from planes and satellites that showed the entire Nazca, but at a resolution of a few centimeters per pixel, it would take the human eye years, if not decades, to analyze all the data.

They left the job to an AI system. Although it was not easy to train artificial vision, with so few previous images and so many different ones, the machine came up with 1,309 candidates. This figure was obtained from a previous selection, also made by AI, with 36 images for each candidate. With this selection, the researchers carried out a field expedition between September 2022 and February 2023. As a result, as reported in the scientific journal PNAS, 303 new geoglyphs were added to this cultural heritage of humanity. All of them are relief-type geoglyphs.

The newly discovered figures bring the total number of geoglyphs found in Nazca to 50 linear and 683 relief ones, some of which are geometric, while others form figures. The large number allowed the authors of this work to identify patterns and differences. Some of the geoglyphs depict wild animals or plants (monkey, condor, cactus…). However, another 82% or so show human elements or elements modified by humans (humanoids, domesticated animals such as llamas, and many decapitated heads, up to 33% of the total). "These are scenes of human sacrifice," says Sakai. "The location of these severed heads and almost all the other relief-type geoglyphs provides another clue, in this case about their purpose."

The accumulation of data that made this work possible reveals a double relationship. On the one hand, these relief forms are found a few meters from one of the many paths that cross the desert. These are not roads as such, but paths created by the passage of people until a path is created. According to the authors of the study, these creations were made to be seen by travelers. On the other hand, the large linear figures appear very close, a few meters from one of the many straight lines that cut through the pampas. Here, according to Sakai, symbolic meaning reigns: “The linear geoglyphs are drawn at the starting and ending points of the pilgrimage route to the ceremonial center of Cahuachi. These were ceremonial spaces with animal forms and other figures. Meanwhile, the relief geoglyphs can be seen while walking along the paths.” Cahuachi was the center of spiritual power of the Nazca culture from about 100 BC. to 500 AD, and the authors believe that the larger forms may have been ceremonial stops during pilgrimages to or from there.

According to the authors, these explanations do not necessarily rule out other possible functions that have been attributed to the Nazca lines and figures, such as calendars, astronomical maps, or even systems for capturing the small amounts of water that fell. What they are certain of is that artificial intelligence can revolutionize archaeology, as it did with Nazca.