Science & Technology

Aerial survey reveals how Mesoamerican culture built cities

The location of the buildings revealed by Lidar. Image credit: Takeshi Inomata (provided)

Few civilizations have evolved independently on Earth, and the Olmec civilization is one of them. Olmecs was the earliest known major Mesoamerican civilization that emerged in 1600 BC and lasted until 400 BC, when many villages became uninhabitable due to environmental changes.

Olmecs influenced many later civilizations, including Maya. Researchers now know that the Olmec and Maya settlements cover large areas of Mexico and Guatemala, but many of their ancient settlements have not yet been discovered or have been thoroughly studied. not. To make matters worse, they are often hidden by vegetation.

To map these hidden structures, a team led by Takeshi Inomata of the University of Arizona uses lidar, a remote sensing technique that pulses a laser to measure the distance to the earth (variable distance). We conducted an aerial survey. It’s a bit like radar, but uses light instead of radio waves. Lidar is very useful in archeology because it reveals elements that may not be visible to the naked eye on the surface.

Inomata et al. Started with a high-resolution survey covering an area of ​​1000 square kilometers, but also used public data obtained by the Mexican government covering an area of ​​85,000 square kilometers.

“Study in this large area was unthinkable a few years ago. This kind of dataset really revolutionized the way we do archaeological research,” Inomata told ZME Science.

Part of the study area. Image credit: Takeshi Inomata.

By using lidar, we were able to image 463 sites even in areas covered with thick jungle vegetation. Based on the results, there seem to be five types of architecture and settlement layouts. These may correspond to different eras of Olmec and Maya civilizations.

It was already known that the cities of these civilizations were designed based on the patterns of the universe. New discoveries suggest that San Lorenzo’s main Olmec center (built in the 2nd millennium BC) was based on the ancient Mesoamerican calendar. Other sites in the region suggest that this type of impact was widespread.

“Their orientations vary, and in some cases it looks like they tried to fit their large complex into the available flat space. But if possible, the complex at sunrise on a particular date. It seems to be fit together. Probably the day when the sun passes the zenith (the day when the sun passes vertically from the ground) around May 10 in this area, “says Inomata. “This day is the beginning of the rainy season and the planting of corn. Some complexes face the sunrise 40 days before the zenith, while others face the sunrise 60 or 80 days before. This is the 20th. It seems to show unit-based Mesoamerican calendar prototypes. If we are correct, they may be the earliest representations of such a calendar concept we can see. “

A rider-based 3D image of a site called Buenavista on the day of sunrise alignment. Image credit: Takeshi Inomata.

Another interesting finding was that these sites appeared to feature many rectangular structures, including monuments. This is somewhat surprising, as the Olmec site often featured monumental pyramidal mounds.

“The main finding is that we now know that these widely standardized complexes in the horizontal direction are spread over the western Maya and the Olmec region. Most of those places are unknown and Even though the existence of some mounds was known, their overall rectangular shape was not recognized. I thought the pyramids were characteristic of Meso-American civilization, but before the development of the pyramids. There was a monumental structure that emphasized the horizontal dimensions and standardized rectangular design. “

Having been able to see these places with the eyes of a bird, archaeologists can explore them on the ground to see what more they can find about these ancient civilizations. However, ground surveys tend to take much longer than aerial surveys.

“We have been conducting excavations and ground surveys in the eastern part of this study area. We will continue ground surveys in that area, but it will take years to survey the many places we have found in this large area. We need the involvement of many other scholars, “Inomata adds to ZME Science.

Excavation in La Carmerita. Image credit: Takeshi Inomata.

As anthropologist Robert M. Rosenswig points out in an accompanying news and view article, this accurate mapping of Mesoamerican archaeological sites helps document the archeology of the southern Gulf population. This is a very important first step. The next few decades.

There is still a lot to learn about these ancient cultures, and new technologies can be very helpful.Last year, Inomata et al. Also shed new light Archaeologists were forced to rethink how civilization evolved in various Maya settlements.

A study entitled “The Origin and Spread of the Formal Ritual Complex of the Olmecs and Maya Regions Revealed by Aerial Riders” was published in Nature.

Aerial survey reveals how Mesoamerican culture built cities Aerial survey reveals how Mesoamerican culture built cities

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