Maya and the corn that supported them had amazing southern roots, ancient DNA shows

(ORDO NEWS) — In Mayan creation myths, the gods created humans from corn. Now a new study from Belize suggests that maize did play a major role in the origins of the ancient Maya.

More than half of their ancestors can be traced back to migrants who arrived from South America about 5,600 years ago, probably bringing new varieties of maize with them. that supported one of the great cultures of Mesoamerica.

These previously unknown migrants “were the first pioneers who, in fact, planted the seeds of the Maya civilization” that arose about 4,000 years ago, says archaeologist and study co-author Jaime Ave. A native Belizean now working at Northern Arizona University, he, like many Belizeans, has some Mayan ancestry. “Without corn, there would be no Maya.”

The discovery reveals a significant new source of Maya ancestors, whose civilization spanned a third of Central America and Mexico, dotting the region with cities and monuments during its heyday over 1,000 years ago.

Today, the Maya are an ethnolinguistic group with at least 7 million native Central Americans. The study also suggests that, as in Europe, where farming originated with immigrants from the Middle East, farming in the Americas spread at least in part through the movement of people, rather than simply as know-how passed between cultures.

“This article is really groundbreaking,” says Mary Paul, a Maya archaeologist at Florida State University. “It’s a dramatic revelation that’s really moving.”

Ave, a Mayan archaeologist and former director of the Belize Institute of Archaeology, has long wondered how the Maya are related to the hunter-gatherers and early farmers who brought maize, cassava and chili to what is now Mexico, Belize and Guatemala. But the poor preservation of bones and DNA in hot, humid climates left few clues.

The new study analyzes remains from two rock shelters on the steep slopes of old-growth rainforest in the Bladen Game Reserve in southwestern Belize, 2.5 kilometers from the nearest road. Since 2014, archaeologist Keith Prufer of the University of New Mexico at Albuquerque, wildlife biologist Said Gutiérrez of the Jaakshe Conservation Foundation, and colleagues have unearthed more than 85 skeletons from shallow graves in the dry earthen floors of rock shelters.

Archaeologists have conducted direct radiocarbon dating of 50 individuals, determining that they lived between 1,000 and 9,600 years ago.

Then population geneticist David Reich of Harvard University and his team were able to extract high-quality ancient DNA from the bones of the inner ear of 20 people – “the oldest human DNA from tropical rainforests,” says Reich. They analyzed 1.2 million nucleotide bases in the genomes and compared them with the DNA of ancient and living people from the Americas.

The comparison showed that the earliest humans, buried in rock sheds 9600-7300 years ago, are very similar to hunter-gatherers descended from an ancient migration from North to South America. But after 5,600 years ago, major changes were recorded in the DNA.

All 15 subjects were the closest relatives of another group of indigenous people who today live from northern Colombia to Costa Rica and speak the Chibchan languages. “This is obviously a major migration to the Maya region of people related to Chibchan speakers,” says Reich.

The migration had long-term effects: Reich’s team found that the living Maya inherited more than half of their DNA from this influx from the south, they reported today in the journal Nature Communications. Half of the remainder comes from the ancient hunter-gatherers who first appeared in the region, and the rest from the ancestors of the inhabitants of the Mexican highlands.

The change in population eventually led to a new diet. Proofer and archaeologist Douglas Kennett of the University of California at Santa Barbara previously analyzed carbon isotopes from the teeth of people in rock shelters, which shows what kind of food they ate.

As reported in Science in 2020, they found a steady increase in corn consumption over time. Among ancient hunter-gatherers, corn averaged less than 10% of their diet. The early migrants from the south also ate relatively little corn. But then, between about 5,600 and 4,000 years ago, the share of corn skyrocketed from 10% to 50%, “the earliest evidence that corn is a staple grain,” Proofer says.

The shift to corn occurred hundreds of years after the influx of migrants, but the team says its results are consistent with the evolving history of corn cultivation. This plant was partially domesticated as early as 9,000 years ago in southwestern Mexico, but over the past 8 years, genetic and archaeological evidence has shown that it was only fully domesticated 6,500 years ago – in places in Peru and Bolivia.

There, farmers have grown larger and more nutritious cobs than the partially domesticated corn found in Mexico 5,300 years ago, says archaeologist Logan Kistler of the Smithsonian’s National Museum of Natural History (NMNH).

Taken together, the evidence suggests that 5,600 years ago, migrants brought improved varieties of corn from the south, possibly with small-garden corn farming techniques, says Kennett, co-author of the paper. By 4,000 years ago, it had become the main agricultural crop.

This scenario may explain why one of the early Mayan languages ​​includes the word Chibchan, which means corn, says linguist and study co-author David Mora-Marin of the University of North Carolina at Chapel Hill.

By tracing the origins of one of the great peoples of Mesoamerica, the genetic and isotopic work is also shedding light on the evolutionary roots of one of the world’s most successful crops, says archaeobotanist Dolores Piperno of NMNH and the Smithsonian Tropical Research Institute. “It really changes our knowledge of how corn spread.”

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