The Nazca Lines form giant animals visible only from the sky, and their purpose is still unknown

Etched into a stretch of arid plateau in southern Peru are hundreds of enormous drawings — a hummingbird, a monkey with a curling tail, a spider, a killer whale, and long dead-straight lines that run for miles across the desert floor. Most of them are so large that a person standing in the middle of one would see only a shallow trench in the gravel, not a picture at all. The full shapes snap into focus only from high above, which is exactly what makes the Nazca Lines one of archaeology’s most durable puzzles: a people who never flew built art meant to be read from the sky, and more than two thousand years later there is still no settled explanation for why.

A gallery carved across the Peruvian coastal desert

The geoglyphs sit on the Pampa de Nazca, a bone-dry plain between the towns of Nazca and Palpa where rain almost never falls and the wind rarely disturbs the surface. That climate is the reason the images survived at all. The ground is coated with a layer of dark, iron-oxidized stones lying over pale sand, and the ancient artists simply raked away the dark pebbles to expose the lighter earth underneath, leaving lines a few inches deep. On a windier or wetter landscape they would have been erased within a generation.

The area’s cultural weight is formally recognized: the desert around Nazca and Palpa is a UNESCO World Heritage Site, listed for a concentration of geoglyphs unmatched anywhere on Earth. They were produced mainly by the Nazca culture, which flourished along Peru’s southern coast from roughly 100 BCE to 800 CE, with some of the oldest markings predating that window. The designs fall into two broad families — sweeping geometric forms and straight lines on one hand, and figurative images of animals, plants, and human-like beings on the other.

The 303 figures that artificial intelligence pulled from the sand

For nearly a century, the catalog of known figurative geoglyphs grew slowly, one painstaking survey at a time. That changed when a research team trained machine-learning models to scan high-resolution aerial imagery for the faint traces human eyes miss. In a study published in the Proceedings of the National Academy of Sciences, researchers led by Masato Sakai of Japan’s Yamagata University reported that an AI-assisted survey identified 303 previously unknown figurative geoglyphs in roughly six months, nearly doubling the number found over the previous nine decades of fieldwork.

The newly surfaced images were not the giant, kilometer-scale line drawings that made the site famous. Many were smaller relief-style figures, often clustered along old footpaths, depicting humans, domesticated animals such as llamas, birds, fish, cats, and scenes of people interacting with animals. Among the more striking finds were orcas shown wielding weapons and figures tied to acts of ritual violence. According to reporting on the survey, the AI approach let the team spot candidate figures far faster than manual inspection, then verify the most promising ones on the ground.

Why the largest images can only be read from above

The scale is what defies intuition. The famous animal figures span tens to hundreds of meters, and some of the straight lines extend for miles, so no observer at ground level can perceive the design as a coherent whole. That fact fueled a century of speculation, including fringe claims that the lines were runways or signals for visitors from elsewhere — ideas that mainstream archaeologists reject. The more grounded implication is subtler: the builders were content to create images whose complete form no living person on the plain would ever see, which points toward an audience that was not standing on the ground.

Constructing them did not require flight or advanced technology. The lines are shallow and were laid out with simple surveying methods — stakes, cords, and sight lines — that let the Nazca keep long stretches remarkably straight and reproduce curved figures at scale. The engineering, in other words, is understood. The intent is not.

The competing theories about who the drawings were meant for

Explanations have accumulated for generations, and no single one has won out. An early and influential idea held that the lines encoded astronomical alignments, marking the rising and setting points of the sun, moon, or stars and functioning as a kind of calendar tied to planting and water. Later work weakened that view, finding too few reliable alignments to support a systematic sky map.

A water-and-fertility reading gained ground instead: in a desert where survival hinged on scarce groundwater, the geoglyphs may have been part of rituals appealing to deities for rain, with the giant figures made to be seen by gods above rather than people below. The most recent survey adds weight to a related, human-scale explanation. Many of the smaller relief figures cluster along winding paths, consistent with the idea that they were viewed up close by travelers and used in communal rites during pilgrimages toward Cahuachi, a major Nazca ceremonial center. The two scales of art may have served two different purposes — the small figures for people walking past, the giant ones for something else entirely.

What keeps the geoglyphs an open case

Even with hundreds of new figures mapped and a plausible ritual framework taking shape, the core question resists a final answer. The Nazca left no written records, so every interpretation is reconstructed from the images themselves, their placement, and the sparse archaeology around them. That is why the site still appears on lists of ancient places whose full story remains unresolved, and why researchers describe the purpose as debated rather than known.

What has changed is the pace of discovery. Where the catalog once grew by a handful of figures per decade, machine learning has begun revealing them in batches, and analysts expect the total to keep climbing as more of the plain is scanned in fine aerial detail. Each new figure narrows the range of plausible explanations without yet closing it — a mystery being solved in increments, one raked line at a time.

This article was researched and drafted with the assistance of AI and reviewed before publication.

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