LiDAR Reveals 478 Olmec and Maya Ceremonial Complexes in Mexico | Sci.News

Using a revolutionary technology known as LiDAR (laser imaging, detection and ranging), an international team of archaeologists has discovered 478 rectangular and square complexes, probably dating from 1050 BCE to 400 BCE, in the Olmec region and the western Maya lowlands of Mexico. The LiDAR data have also revealed that the earlier Olmec center of San Lorenzo had a central rectangular space, which possibly provided the template for later sites.

“The layouts and orientations of Mesoamerican cities were closely tied to cosmologies, concepts of time and ritual practices,” said Professor Takeshi Inomata, an anthropologist in the School of Anthropology at the University of Arizona, Tucson, and his colleagues.

“Formal site plans dating to the Early Formative (1,800-1,000 BCE) and Middle Formative (1,000-350 BCE) periods may have provided symbolic templates for later urban formations, and thus the origins and development of early standardized spatial configurations present critical information for the understanding of social and cultural processes in Mesoamerica.”

“An important area in this regard is the Isthmian region of southern Mexico and western Guatemala, encompassing the Gulf Olmec region, where Olmec centers, such as San Lorenzo and La Venta, developed during the Early and Middle Formative periods, and the western Maya lowlands, where many Maya centers emerged during the Late and Terminal Formative periods (350 BCE to 250 CE) and the Classic period (250-950 CE).”

The newly-discovered complexes are located in a broad area encompassing the Olmec region and the western Maya lowlands.

They were likely constructed between 1050 BCE and 400 BCE and were built by diverse groups nearly a millennium before the heyday of the Maya civilization.

They share similar features with San Lorenzo, which peaked between 1400 and 1100 BCE.

The site of Aguada Fenix in the Maya area and other related sites began to adopt San Lorenzo’s form and formalize it around 1100 BCE.

At San Lorenzo, Professor Inomata and co-authors also found a previously unrecognized rectangular space.

“The sites are big horizontally but not vertically. People will be walking on one and won’t notice its rectangular space, but we can see it with LiDAR really nicely,” Professor Inomata said.

The team’s work suggests that San Lorenzo served as a template for later constructions, including Aguada Fénix.

“People always thought San Lorenzo was very unique and different from what came later in terms of site arrangement,” Professor Inomata said.

“But now we show that San Lorenzo is very similar to Aguada Fénix — it has a rectangular plaza flanked by edge platforms.”

“Those features become very clear in LiDAR and are also found at Aguada Fénix, which was built a little bit later.”

“This tells us that San Lorenzo is very important for the beginning of some of these ideas that were later used by the Maya.”

The complexes uncovered by the team were likely used as ritual gathering sites. They include large central open spaces where lots of people could gather and participate in rituals.

The archaeologists also analyzed each site’s orientation and found that the sites seem to be aligned to the sunrise of a certain date, when possible.

“There are lots of exceptions; for example, not every site has enough space to place the rectangular form in a desired direction, but when they can, they seem to have chosen certain dates,” Professor Inomata said.

“While it’s not clear why the specific dates were chosen, one possibility is that they may be tied to Zenith passage day, which is when the sun passes directly overhead. This occurs on May 10 in the region where the sites were found. This day marks the beginning of the rainy season and the planting of maize.”

“Some groups chose to orient their sites to the directions of the sunrise on days 40, 60, 80 or 100 days before the zenith passage day. This is significant because the later Mesoamerican calendars are based on the number 20.”

San Lorenzo, Aguada Fénix and some other sites have 20 edge platforms along the eastern and western sides of the rectangular plaza.

Edge platforms are mounds placed along the edges of the large rectangular plazas.

They define the shape of the plazas, and each are usually no taller than about 0.9 m (3 feet).

“This means that they were representing cosmological ideas through these ceremonial spaces. In this space, people gathered according to this ceremonial calendar,” Professor Inomata said.

The research is described in a paper published in the journal Nature Human Behavior.

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T. Inomata et al. Origins and spread of formal ceremonial complexes in the Olmec and Maya regions revealed by airborne lidar. Nat Hum Behav, published online October 25, 2021; doi: 10.1038/s41562-021-01218-1