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Until recently, archaeology was limited by what a researcher could see while standing on the ground. But light detection and ranging, or lidar, technology has transformed the field, providing a way to scan entire regions for archaeological sites.
With an array of airborne lasers, researchers can peer down through dense forest canopies or pick out the shapes of ancient buildings to discover and map ancient sites across thousands of square miles. A process that once required decadeslong mapping expeditions, and slogging through jungles with surveying equipment, can now be done in a matter of days from the relative comfort of an airplane.
But lidar maps are expensive. Takeshi Inomata, an archaeologist at the University of Arizona, recently spent $62,000 on a map that covered 35 square miles, and even was deeply discounted. So he was thrilled last year when he made a major discovery using a lidar map he had found online, in the public domain, entirely for free.
The map, published in 2011 by Mexico’s National Institute of Statistics and Geography, covered 4,440 square miles in the Mexican states of Tabasco and Chiapas. It was made as part of the institute’s mission to create accurate maps to be used by businesses and researchers.
Inomata learned about the map from Rodrigo Liendo, an archaeologist at the National Autonomous University of Mexico. The resolution of the map was low. But the outlines of countless archaeological sites stood out to Inomata. So far, he has used it to identify the ruins of 27 previously unknown Maya ceremonial centers that contain a type of construction that archaeologists had never seen before. These sites may hold insights into the origins of Maya civilization.
“We can see a much better picture of the entire society,” Inomata said.
His findings have not yet been peer-reviewed, but Inomata has presented his work at four conferences during the past year. “The stuff he is finding is crucial for our understanding of how Maya civilization developed,” said Arlen Chase, an archaeologist at Pomona College, who did not contribute to Inomata’s work.
Chase was among the early adopters of lidar. In 2009, he used it to map Caracol, a Maya city in Belize, where he and Diane Chase, an archaeologist at Claremont Graduate University, have worked for 35 years. The two are married, and their son, Adrian, a Ph.D. candidate at Arizona State University, is now using lidar to compare the square footage of more than 4,000 homes in Caracol as a way to infer social inequality. (Presumably then, as now, wealthier residents had larger homes.) Such an analysis would have been all but impossible before lidar.
The Maya civilization arose between 1,000 B.C. and 400 B.C. When Inomata first began studying the Maya as a graduate student in the 1980s, his professors were mainly interested in the Classic Period, between A.D. 250 and A.D. 900, when the Maya were at their political and economic peak. Inomata was more interested in how Maya culture began, and the artifacts that could answer his questions were buried even deeper underground.
Years passed before he had enough grant money, and a sufficiently secure academic appointment, to start that project. Finally, in 2005, he and his wife, Daniela Triadan, an anthropologist at the University of Arizona, began excavating the ancient city of Ceibal in the Petén rainforest in Guatemala, where they discovered some of the earliest known Maya buildings. The city’s ceremonial center dates to 950 B.C., but Ceibal didn’t have permanent housing until 200 years later.
Triadan and Inomata believe that the earliest Maya were probably still living a migratory lifestyle, coming to Ceibal only for religious purposes. How they transitioned to settling down in large cities and what role the Olmec civilization, which preceded the Maya, played in the founding of the Maya civilization are the big questions that Inomata and Triadan are seeking to answer. Olmec-style artifacts were found among the earliest buildings at Ceibal, indicating that the Maya civilization was influenced by the Olmec from the beginning. “The relationship between the Maya and Olmec gets at the origins of Mesoamerican civilization overall,” Inomata said.
The Olmec and the Maya civilizations differed in important ways. Power in the Olmec state was concentrated in the hands of a single ruler; the famous Olmec stone heads, which were carved from enormous boulders, may have been portraits of their kings. Less is known about the earliest Maya rulers, because they didn’t glorify their kings with monuments until much later. The Maya and Olmec also developed unique languages and their own architectural and artistic styles.
After discovering some of the earliest known Maya buildings at Ceibal, the obvious next step for understanding how the Olmec influenced the beginnings of Maya culture was to study the territory between Ceibal and the centers of the Olmec culture. The Mexican government’s publicly available lidar map made Inomata’s job surprisingly easy.
The 27 sites he identified on the map have a type of ceremonial construction that Inomata and his colleagues had never seen before — rectangular platforms that are low to the ground but extremely large, some as long as two-thirds of a mile.
“If you walk on it, you don’t realize it,” Inomata said of the platforms. “It’s so big it just looks like a part of the natural landscape.” The similarities between these sites and the early buildings they found at Ceibal led them to believe they both date to sometime between 1000 B.C. and 700 B.C.
“The amount of labor is staggering,” Triadan said. “The mass of earth moved is unbelievable. These people were doing some crazy stuff.” She described a scene of hundreds of people coming together from across the region to dig and carry baskets of dirt to build the platforms. “We may have relatively mobile populations who are putting a lot of effort into these massive communal enterprises,” she said.
Inomata and Triadan are now leading excavations at the largest ceremonial center they found on the free lidar map, a site they have named Aguada Fenix, where they hope to learn more about the earliest rituals of the ancient Maya.
Viewing the archaeology of an entire region, in detail, will allow archaeologists to answer bigger-picture questions, such as the ones that Inomata has about the interactions the Maya had with the Olmec at the beginning of their civilization.
The lidar map that Inomata used to make his discovery is continually being expanded by the Mexican government to cover new areas. Other countries, including the United States, have similar mapping programs underway.
The future pattern,” Inomata said, “will be that everything will be covered by lidar, like topographic maps today.”