Modern technology has helped archaeologists add two more pieces to the puzzle of the history of the Americas.
In Mexico, LiDAR (light detection and ranging) equipment uncovered what researchers say is the largest and oldest known Maya monument, while in neighbouring Belize, isotopic analysis of human remains provided the earliest timeline for the adoption of maize as a staple crop.
The discovery at Tabasco near the border with Guatemala suggests the Maya civilisation developed more rapidly than previously thought and hints at less social inequality than in later periods, according to the international research team led by Takeshi Inomata and Daniela Triadan from the University of Arizona US.
Known as Aguada Fénix, the monument lurked beneath the surface for centuries, despite measuring 1400 metres by 400 and standing 15 metres high in places. It was discovered when laser beams penetrated the tree canopy, and their reflections off the ground revealed the three-dimensional forms of archaeological features.
“This area is developed. It’s not the jungle – people live there,” says Inomata. “But this site was not known because it is so flat and huge. It just looks like a natural landscape.”
Excavation revealed nine causeways extending from the main platform, and radiocarbon dating of 69 samples of charcoal determined the complex was constructed between 1000 and 800 BCE.
The discovery marks a time of major change in Mesoamerica and has several implications, Inomata says.
First, until now it had been thought Maya civilisation developed gradually, with small villages appearing between 1000 and 350 BCE, along with the use of pottery and some maize cultivation. The discovery of such a large monument of such an age contradicts that.
Second, the site looks similar to the older Olmec centre of San Lorenzo to the west, but the lack of stone sculptures related to rulers and elites suggests less social inequality than San Lorenzo and highlights the importance of communal work in the earliest days of the Maya.
The research findings are published in the journal Nature.
The results of the second study, published in the journal Science Advances, indicate that maize began to take on an increasingly important dietary role for humans in Mesoamerica roughly 4700 years ago, and within 700 years had become a true staple crop, accounting for as much as 70% of total diet.
An international team led by the University of New Mexico (UNM) and the University of California Santa Barbara, US, studied two well-preserved sites in Belize that provide a largely uninterrupted 10,000-year record of human remains.
Here, they found 52 individuals buried at a wide range of depths within the shelters and determined their ages via radiocarbon dating. They then determined each individual’s level of maize consumption by leveraging a defining characteristic of the crop: it employs the relatively rare C4 photosynthetic pathway.
This metabolic quirk imparts a distinct carbon isotopic fingerprint, which is preserved in both the collagen proteins and apatite minerals in the bones of maize consumers.
The researchers found that individuals older than 4700 years showed no clear evidence of maize consumption, while some dating between 4700 and 4000 years ate a diet consisting of as much as 30% maize. The youngest samples, dating to less than 4000 years, showed evidence for as much as 70% maize consumption.
“We know that people had been experimenting with the wild ancestor of maize, teosintle, and with the earliest early maize for thousands of years, but it does not appear to have been a staple grain until about 4000 BP,” says UNM’s Keith Prufer, the principle investigator
“After that, people never stopped eating corn, leading it to become perhaps the most important food crop in the Americas, and then in the world.”