How hundreds of mysterious Nasca lines have been uncovered—with the help of AI

The discovery of geoglyphs in southern Peru has been supercharged by artificial intelligence (AI). In just six months, more than 300 new figures were identified, almost doubling the previously known number. Etched into the desert, the relief-type glyphs depict domesticated animals, anthropomorphic figures, and human heads.

A team from Yamagata University’s Nasca Institute, led by archaeologist Masato Sakai and backed by the IBM Research center, trained an object-detection AI model with high-resolution imagery to refine their investigation into the distribution of geoglyphs in the Nasca desert. The newly identified glyphs are relatively small, and may have fulfilled roles quite different from those of the vast, sprawling geoglyphs that the Nasca desert is best known for. The latest findings are not only a striking addition to the catalog but also a vital aid in helping reveal part of the mystery surrounding these enigmatic designs.

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A game changer

The Nasca Lines are massive geoglyphs of animals, people, plants, and geometric designs that adorn the high desert of southern Peru. Examples of note include the famous depictions of a hummingbird, a spider, and a monkey with a long, spiraling tail.

Thought to date to as early as 100 B.C., the well-known giant figurative geoglyphs average almost 300 feet in length, with some recognizable even from ground level. The latest discoveries are thought to date to roughly the same period and are, by contrast, about 30 feet in size, harder to detect, and tucked into the slopes and trails of the desert landscape.

When Sakai set out to study the geoglyphs, his intention was to understand their real purpose. He began his research in 1994, and from 2004 onward organized a research team that conducted field investigations using a combination of satellite images, aerial photographs, and drone imagery. The sheer size of the area they scoped (spanning 250 square miles) made it a painstaking process, until 2018, when they followed a science professor’s recommendation to deploy AI.

Sakai, working with IBM in New York, used an image-recognition AI model that had been pretrained to scan aerial images of the entire Nasca pampa and surrounding deserts on a large-scale image dataset. The AI model’s suggestions were screened by archaeologists, who picked out 1,309 sites with potential for authenticity. A field survey was then carried out, which allowed the team to examine the geoglyph candidates in situ and make use of drone photography for verification.

This method was a “game changer,” Sakai writes. The new geoglyphs were harder to detect, due not only to their size but also to erosion and their more subtle contrast with the mottled desert surface. They would have been difficult to detect with the flyovers of the past.

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Desert messages

Nasca geoglyphs have intrigued scientists for a century. Peruvian archaeologist Toribio Mejía Xesspe and U.S. anthropologist Alfred L. Kroeber were the first to carry out systematic studies of the lines, beginning in 1926—well before they were brought to public awareness when commercial planes first flew over Peru in the 1930s. Some early researchers believed the lines were related to astronomy or the calendar, but a later study suggested they were probably ritual places serving to encourage crop fertility.

The recent discoveries have been crucial in explaining the purpose of and relationships among the glyphs. Sakai’s team concluded that the large animal geoglyphs tend to cluster at the start and end points of pilgrimages to sacred sites and temples and that these figures were likely plazas where community rituals were conducted.

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The relief-style glyphs, however, were found close to walking trails and seem to have been created by individuals or small groups. Their subject matter (humans, llamas, fish, plants, and even orcas carrying weapons) suggests they were intended as messages to travelers.

For Sakai, the use of AI in archaeology could prove as transformative as the advent of aerial photography in the early 20th century. Many of the Nasca glyphs have been accidentally or maliciously damaged, and they are falling victim to the rise of flash flooding due to climate change. Sakai hopes that rapidly cataloging and mapping these fragile artworks will help safeguard them for the future.