Using a revolutionary technology known as LiDAR (laser imaging, detection and range finding), an international team of archaeologists have discovered 478 rectangular and square complexes, probably dating from 1050 BCE to 400 BCE, in the region. Olmec and the western Mayan lowlands of Mexico. LiDAR data also revealed that the former Olmec center of San Lorenzo had a central rectangular space, which may have provided the template for later sites.
“The dispositions and directions of Mesoamerican cities were closely related 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, et al. colleagues.
“Official site maps dating from the initial (1800-1000 BCE) and middle (1000-350 BCE) formation periods may have provided symbolic models for later urban formations. understanding social and cultural processes in Mesoamerica.
“An important area in this regard is the Isthmian region of southern Mexico and western Guatemala, encompassing the region of the Olmec Gulf, where Olmec centers, such as San Lorenzo and La Venta, developed during the periods of initial and middle education, and the western Mayan lowlands. , where many Mayan centers emerged during the late and terminal formative periods (350 BCE to 250 AD) and the Classical period (250-950 AD).
The newly discovered complexes are located in a large area encompassing the Olmec region and the western Mayan lowlands.
They were probably built between 1050 BCE and 400 BCE and were built by various groups nearly a millennium before the height of Mayan civilization.
They share similar characteristics with San Lorenzo, which peaked between 1400 and 1100 BCE.
The site of Aguada Fenix in the Mayan region and other related sites began to take the form of San Lorenzo and formalize it around 1100 BCE.
In San Lorenzo, Professor Inomata and his co-authors also found a previously unknown rectangular space.
“The sites are large horizontally but not vertically. People will walk on it and not notice its rectangular space, but we can see it very well with LiDAR, ”Prof. Inomata said.
The team’s work suggests that San Lorenzo served as a model for later constructions, including Aguada Fénix.
“People have always thought that San Lorenzo was very unique and different from what happened later in terms of the layout of the site,” said Professor Inomata.
“But now we show that San Lorenzo is very similar to Aguada Fénix – it has a rectangular plaza flanked by edge platforms.”
“These features become very clear in LiDAR and are also found in Aguada Fénix, which was built a bit later.”
“This tells us that San Lorenzo is very important for the start of some of these ideas which were then used by the Mayans.”
The complexes discovered by the team were likely used as ritual assembly sites. They include large central open spaces where many people can gather and participate in rituals.
Archaeologists also analyzed the orientation of each site and found that the sites appear to be aligned with sunrise of a certain date, when possible.
“There are a lot of exceptions; for example, not all sites have enough space to place the rectangular shape in the desired direction, but when they can, they seem to have chosen certain dates, ”Prof. Inomata said.
“Although it is not clear why the specific dates were chosen, one possibility is that they may be linked to the day of the Zenith crossing, that is, when the sun passes directly over us. This happens on May 10 in the region where the sites were found, which marks the start of the rainy season and the planting of maize.
“Some groups have chosen to orient their sites in the direction of sunrise on days 40, 60, 80 or 100 days before zenith day. This is important because the latest Mesoamerican calendars are based on the number 20. ”
San Lorenzo, Aguada Fénix, and a few other sites have 20 border platforms along the east and west sides of the rectangular plaza.
Edge platforms are mounds placed along the edges of large rectangular plazas.
They define the shape of the squares, and each usually does not exceed about 0.9 m (3 feet).
“This means that they represented cosmological ideas through these ceremonial spaces. In this space, people gathered according to this ceremonial calendar, ”said Prof. Inomata.
The research is described in a paper published in the journal Nature Human Behavior.
T. Inomata et al. Origins and dissemination of formal ceremonial complexes in the Olmec and Mayan regions revealed by airborne lidar. Nat Hum behaves, published online 25 October 2021; doi: 10.1038 / s41562-021-01218-1