From the ground, the Nazca Lines are hard to see. From the air, they are unmistakable: a hummingbird with a wingspan of 90 meters, a monkey with a spiral tail, a spider, a tree, a pair of hands. Around them, hundreds of straight lines and geometric figures cross a plateau roughly the size of Manhattan in southern Peru.

The lines were made by the Nazca culture, which flourished in the region between roughly 100 BC and AD 800, with some of the earliest geoglyphs attributed to the earlier Paracas culture. They were created by removing the dark, oxidized stones that cover the desert surface to expose the lighter sand beneath. Because the Nazca Desert receives almost no rain and very little wind at ground level, the figures have survived for two thousand years with relatively little degradation.

They came to wider attention in the 1920s, when commercial flights between Lima and Arequipa began passing overhead and pilots reported strange markings. The German-Peruvian archaeologist Maria Reiche devoted her life to mapping them, working from a small house at the edge of the desert from 1940 until her death in 1998.

Reiche proposed that the lines were an astronomical calendar, with figures aligned to the rising and setting points of the sun, moon, and significant stars at the solstices and equinoxes. Her theory dominated popular accounts for decades.

Other theories arrived. Erich von Daniken, in his 1968 book Chariots of the Gods, proposed that the straight lines were runways for extraterrestrial spacecraft. The argument required ignoring the fact that the lines run across loose sand and would collapse under the wheels of any aircraft heavier than a paper airplane. The theory was popular regardless.

The current consensus draws on water.

Mainstream archaeology has moved on from both Reiche's astronomical model and von Daniken's runways. Statistical reanalysis of Reiche's alignments by the American astronomer Gerald Hawkins in 1968, and later by Anthony Aveni in the 1980s, found that the number of lines pointing at astronomically significant features was no greater than would be expected by chance.

The current consensus draws on water.

The Nazca region is one of the driest inhabited places on Earth. Rainfall is minimal. The Nazca people depended on a network of underground aqueducts called puquios, which tapped groundwater and brought it to the surface for irrigation. Roughly forty of these puquios are still functional today.

Recent fieldwork by Italian archaeologist Giuseppe Orefici, who has led the Nazca Project since 1982, and by Japanese researchers from Yamagata University, has mapped the geoglyphs against the puquio network and the watercourses that drain the surrounding hills. A striking number of the straight lines, it turns out, point toward sources of water — springs, the mouths of seasonal rivers, the heads of puquios.

The figures, meanwhile, appear to cluster near ceremonial sites. The hummingbird sits near a major ritual complex. The monkey is associated with a ridge that, in Andean tradition, was a place of seasonal rainmaking ceremonies.

The current interpretation, supported by most working archaeologists in the region, is that the lines and figures were elements of a ritual landscape concerned primarily with water. They may have been walked in ceremonial procession; many of the figures can be traced as a single unbroken line that begins and ends at the same point, consistent with use as a processional path. Pottery fragments found along these lines, dated to the Nazca period, support the procession hypothesis.

This interpretation does not require any single explanation for every line. Some geoglyphs were probably made as offerings, others as boundary markers, others as records of ceremonies. The Nazca culture used the landscape itself as a medium of communication with the deities they associated with mountains, rain, and fertility.

In 2019 and 2022, two separate research teams using high-resolution satellite imagery and artificial intelligence identified more than 300 previously unknown geoglyphs in the region. Many of these are smaller and earlier than the famous figures, made by the Paracas culture before about 200 BC. They depict humans, llamas, and abstract forms, and they appear along ancient paths between settlements.

This earlier tradition suggests the famous Nazca figures were the culmination of a long-developing artistic and ritual practice, not a sudden eruption of unexplained activity.

The site is now a UNESCO World Heritage Site and is protected, though imperfectly. In 2014, Greenpeace activists damaged the area around the hummingbird geoglyph during a publicity stunt, leaving footprints that may never fully fade. Mining operations and informal settlements continue to threaten the periphery of the site.

The Nazca Lines remain extraordinary. That they can be explained does not make them less so. A people who could plan and execute figures of this scale, working entirely on foot and without ever seeing their full creations from above, were doing something both practical and remarkable. The figures are not signals to the sky. They are messages from a society to itself, and to whatever forces it believed governed the rain.