mayan

Luke Auld-Thomas and Marcello A. Canuto / PACUNAM

A photograph (above) and a reconstructed lidar image (below) of Maya ruins.

In the autumn of 1929, Anne Morrow Lindbergh and her husband, Charles, flew across the Yucatán Peninsula. With Charles at the controls, Anne snapped photographs of the jungles just below. She wrote in her journal of Maya structures obscured by large humps of vegetation. A bright stone wall peeked through the leaves, “unspeakably alone and majestic and desolate — the mark of a great civilization gone.”

Nearly a century later, surveyors once again took flight over the ancient Maya empire, and mapped the Guatemala forests with lasers. The 2016 survey, whose first results were published recently in the journal Science, comprises a dozen plots covering 830 square miles, an area larger than the island of Maui. It is the largest such survey of the Maya region, ever.

The study authors describe the results as a revelation. “It’s like putting glasses on when your eyesight is blurry,” said study author Mary Jane Acuña, director of El Tintal Archaeological Project in Guatemala.

In the past, archaeologists had argued that small, disconnected city-states dotted the Maya lowlands, though that conception is falling out of favor. This study shows that the Maya could extensively “exploit and manipulate” their environment and geography, Acuña said. Maya agriculture sustained large populations, who in turn forged relationships across the region.

Combing through the scans, Acuña and her colleagues, an international 18-strong scientific team, tallied 61,480 structures. These included: 60 miles of causeways, roads and canals that connected cities; large maize farms; houses large and small; and, surprisingly, defensive fortifications that suggest the Maya came under attack from the west of Central America.

“We were all humbled,” said Tulane University anthropologist Marcello Canuto, the study’s lead author. “All of us saw things we had walked over and we realized, oh wow, we totally missed that.”

Preliminary images from the survey went public in February, to the delight of archaeologists like Sarah Parcak. Parcak, who was not involved with the research, wrote on Twitter, “Hey all: you realize that researchers just used lasers to find 60,000 new sites in Guatemala?!? This is HOLY [expletive] territory.”

Parcak, whose space archaeology program GlobalXplorer.org has been described as the love child of Google Earth and Indiana Jones, is a champion of using satellite data to remotely observe sites in Egypt and elsewhere. “The scale of information that we’re able to collect now is unprecedented,” Parcak said, adding that this survey is “going to upend long-held theories about ancient Maya society.”

With support from a Guatemala-based heritage foundation called Pacunam, the researchers conducted the massive and expensive survey using lidar, or light detection and ranging. They mapped several active archaeological sites, plus well-studied Maya cities like Tikal and Uaxactun.

Lidar’s principles are similar to radar, except instead of radio waves lidar relies on laser light. From an aircraft flying just a few thousand feet above the canopy, the surveyors prickled each square meter with 15 laser pulses. Those pulses penetrate vegetation but bounce back from hard stone surfaces. Using lidar, you can’t see the forest through the invisible trees.