Scientists using airplane-based lidar mapping have discovered thousands of hidden Mayan structures.

Archaeologists have spent more than a century traipsing through the Guatemalan jungle, Indiana Jones-style, searching through dense vegetation to learn what they could about the Mayan civilization that was one of the dominant societies in Mesoamerica for centuries.

But the latest major discovery didn’t even require a can of bug spray.

Scientists using high-tech, airplane-based lidar mapping tools have discovered tens of thousands of structures constructed by the Mayans: defense works, houses, buildings, industrial-sized agricultural fields, even new pyramids. The findings, announced Thursday, are already reshaping long-held views about the size and scope of Mayan civilization.

“This world, which was lost to this jungle, is all of a sudden revealed in the data,” Albert Yu-Min Lin, an engineer and National Geographic explorer who worked on a television special about the new find, told The New York Times. “And what you thought was this massively understood, studied civilization is all of a sudden brand new again.”

Thomas Garrison, an archaeologist at Ithaca College who led the project, called it monumental: “This is a game changer,” he told NPR. It changes “the base level at which we do Maya archaeology.”

The findings were announced by Guatemala’s Mayan Heritage and Nature Foundation, which has been working with a group of European and U.S. archaeologists in employing the lidar system.

The lidar system fires rapid pulses of laser light at surfaces – sometimes as many as 150,000 pulses per second – and measures how long it takes that light to return to sophisticated measuring equipment.

Doing that over and over again lets scientists create a topographical map of sorts.

Computer modeling allows the researchers to virtually strip away half a million acres of jungle that has grown over the ruins. What’s left is a surprisingly clear picture of how a 10th-century Mayan would see the landscape.

The plane that shot lidar pulses at pieces of the Guatemalan jungle did so in less than a day. It unearthed Mayan structures that researchers had literally walked over before, including a temple they thought was a hill.

Using the data, researchers have refined their thoughts about Mayan civilization.

According to The Associated Press, researchers now believe that as many as 10 million people may have lived in the area known as the Maya Lowlands – two or three times as many people as scientists had thought previously.

And because all those people needed to eat, in some areas 95 percent of available land was drained – including areas that have not been farmed since the Mayan civilization fell.

“Their agriculture is much more intensive and therefore sustainable than we thought, and they were cultivating every inch of the land,” Francisco Estrada-Belli, a research assistant professor at Tulane University, told the AP.

During the Maya classic period, which stretched from A.D. 250 to 900, the civilization covered an area twice the size of medieval England, according to National Geographic, but was much more densely populated.

“Most people had been comfortable with population estimates of around 5 million,” said Estrada-Belli, who directs a multidisciplinary archaeological project at Holmul, Guatemala. “With this new data it’s no longer unreasonable to think that there were 10 to 15 million people there – including many living in low-lying, swampy areas that many of us had thought uninhabitable.”

Lidar revealed a previously undetected structure between the two sites that Garrison told the AP “can’t be called anything other than a Maya fortress.”

That and other newly discovered fortresses indicate the Mayans may have been involved in more conflict – even outright warfare – than previously believed.

“It’s this hilltop citadel that has these ditch and rampart systems … when I went there, one of these things is 30 feet tall,” he said.