Advanced laser mapping has revealed more than 60,000 ancient Maya structures beneath the jungles of northern Guatemala.
Set across dozens of hidden cities, the discoveries include houses, palaces and a 90-foot-tall pyramid that was previously thought to be a hill.
Made possible through special laser-equipped airplanes that can "see" through dense jungle, the groundbreaking research suggests that Mayan metropolises were far larger and more complex than previously thought.
Evidence of agriculture, irrigation, quarries and defensive fortifications were widespread, and extensive road networks point to initially unknown levels of interconnectivity between settlements.
Game-changing discoveries
The extent of the findings, first reported by National Geographic, may transform our understanding of how Mesoamerican civilization operated, according to one of the study's co-directors, Marcello Canuto from Tulane University in New Orleans.
"We're discovering that there is more of everything, and the scale is much bigger," he said in a phone interview. "In any given area there were more structures, more buildings, more canals and more terraces (than expected).'"
By extrapolating data from the 2,100-square-kilometer (811-square-mile) site, researchers have also revised their population estimates for the region. They now believe that 10 million people lived in the Maya Lowlands (an area covering parts of present-day Guatetmala and Mexico), a number that is "many times larger" than indicated by previous research.
"The general conceit over the last 100 years has been that the tropics were a bad place to have civilizations and that (the climate) is not conducive to sustaining complex societies," said Canuto, who has worked on Mayan archeology for more than 30 years. "There has always been this assumption that Mayan society was less populated and that there wasn't any infrastructure -- that they were small, independent city-states without much interaction.
"But we're finding that this just isn't true. This research shows that, not only were there lots of people, but also lots of ways that they modified the landscape to render it more productive. The defensive structures that we're finding (also suggest) that there were lots of people and lots of resources, which can create lots of competition."
'Revolutionary' aerial mapping
Central America's thick jungle has often made large-scale surveys of historical sites logistically difficult. But recent developments in a technique known as light detection and ranging (or "lidar") are allowing archeologists to see through even dense forest.
The aerial mapping process is carried out by attaching a lidar sensor to the underside of an airplane. Using the same technology found in self-driving cars, the instrument maps the landscape by emitting pulses of laser light and the time taken for them to return.
The resulting data can reveal ground-level contours, pointing researchers toward man-made structures beneath the canopy. For archeologists, the method allows surveys of great detail and unprecedented size, Canuto said.
"This initiative is bigger than anything that has ever been done before. But it's not just big, it's also covering a wide swathe of this area, so it's actually a representative sample.
"For (archeologists) who work in the tropics, this is entirely revolutionizing the way we do everything," he added. "It's as if you were observing the sun and the stars with your naked eye and then someone invents the telescope."
Potential for archeology
Lidar sensors have previously been used to study other Mesoamerican settlements in Belize, as well as temple complexes in Cambodia. The technology may have archeological potential in other tropical areas, such as the Amazon and central Africa.
For now, the method's greatest barrier is the cost of chartering aircraft, Canuto said. His project was only made possible through funding from the Maya Cultural and Natural Heritage (PACUNAM), a Guatemalan non-profit organization that brought together a consortium of archeologists with different areas of expertise.
But as well as making research economically viable, this type of collaboration may provide new insight into the large datasets created.
"Now we're not limited to one site -- we can see everyone's data," Canuto said. "So instead of having 10 scholars working on 10 individual sites, we had 10 scholars working on individual questions across all the sites. That gives you a regional perspective that no one else has."
Moreover, if archeologists collaborate with experts in other fields, such as ecology and environmental science, aerial mapping may become more cost-effective and widely used.
"The data we use shows what's on the ground... but the other 95 percent of the data is providing a vertical profile of the canopy," Canuto said. "We, as archaeologists, want to know what's under there when you remove the trees. But ecologists want to see biomass and other things that archeologists don't care about."
The digital maps will later be used to carry out targeted ground research. Over the next three years, Canuto and his team hope to scan the entire Maya Biosphere Reserve, an 8,341-square-mile site in Guatemala's Petén region.
