Brazil’s Aratu villagers ate as much corn as the Maya, bone chemistry from 37 sites shows

Bones and teeth from more than 100 people buried at 37 archaeological sites in central and northeastern Brazil have given researchers a direct chemical measure of what precolonial villagers ate, and the largest settlements were running on corn. The Aratu, who lived in open-air villages of up to about 2,000 people between roughly the 9th and 17th centuries, show maize intake comparable to that of Maya or Andean populations.

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The finding upends a long-running debate over how people lived in the Cerrado, Brazil’s tropical savanna. Archaeologists had tended to picture either small bands of mobile foragers or, at the other extreme, intensive sedentary farmers. Isotope chemistry in the skeletons points to something more textured, and it names the Aratu as the group that leaned hardest on maize.

How carbon and nitrogen isotopes record a diet

The work, published in Science Advances on July 15, 2026, and publicized in an October 14 news release, measured stable carbon, nitrogen and oxygen isotopes in bone collagen and tooth enamel. Carbon separates corn from the native plants and fruits of the Cerrado, because maize photosynthesizes differently and leaves a distinct signature. Nitrogen tracks animal protein and position in the food chain, while oxygen reflects drinking water and local conditions.

Lead author Eliane Chim of the Museum of Archaeology and Ethnology at the University of São Paulo, where the project forms part of her doctoral dissertation, summed up the logic of the method by saying that humans are what they eat, and that the record sits in the chemical composition of their bones and teeth.

The samples came from the team’s own excavations and from collections assembled since the 1970s, with more than 270 artifacts evaluated to obtain usable material. Radiocarbon dating of collagen, possible in about 40% of the bones that still held protein, anchored the individuals in time, with the samples falling between 1,100 and 400 years ago. Paleoecological records of seeds, sediments, and plant and animal remains supplied the environmental backdrop.

Aratu villages against Una rock shelters

The study compared two populations living in similar environments. The Aratu occupied large open-air villages and ate corn heavily; the oldest Aratu individuals already showed maize in both collagen and enamel. The Una, among the earliest pottery-making horticulturalists of the Cerrado, sheltered in rock outcrops usually near riverbeds or ponds, kept a more varied diet and consumed less corn. Samples also came from the Caatinga, a semi-arid biome in the northeast, and from the Atlantic Forest.

Because the two groups shared comparable landscapes, the authors conclude that the contrast reflects distinct cultural traditions and economic strategies rather than ecology alone. Both groups practiced polyculture, growing maize alongside other crops and wild foods, which the paper frames as “maize-based polyculture, not monoculture.” That arrangement spread risk across several resources rather than staking a village on one harvest, an important point for a savanna whose conditions differ sharply from the place where corn was first domesticated in Mexico about 9,000 years ago. Earlier research cited in the release holds that maize reached Brazil through the southwestern Amazon at least 6,000 years ago, so the crop had a long road before the Aratu adapted it to Cerrado soils and seasons.

Max Planck and FAPESP researchers on the corn result

André Strauss, the University of São Paulo archaeologist who coordinated the project and advised Chim, said in the Agência FAPESP coverage that corn cultivation there is associated with societies that had larger populations. In the release he added that “this is the first time that its central role in the subsistence of those populations has been demonstrated in Brazil,” and noted that the Aratu rarely feature in popular accounts despite their “unique presence in the Cerrado.”

Patrick Roberts of the Max Planck Institute of Geoanthropology, a co-corresponding author, said in a Max Planck Society statement that the results challenge broader ideas about how agriculture developed in tropical South America. Strauss observed there that the Cerrado has often been overshadowed by the Amazon in discussions of precolonial land use. The project involved 31 researchers from 10 Brazilian universities, the Max Planck Society and institutions in Portugal, Poland and the United States, with funding from FAPESP, the São Paulo Research Foundation. Brazilian researchers hold the first and last author positions, which the team describes as a milestone for Brazilian archaeology.

One detail hints at how the corn was used. Wear marks on ceramic vessels are consistent with the fermenting of alcoholic beverages, which suggests the grain may have served communal or ritual purposes as well as feeding households. A summary on ArchaeologyMag stresses the same pairing of maize with other crops, wild foods and local ecological knowledge.

Chim said the next step is to try to locate the farmlands where people cultivated crops, since the isotopes show what reached the table but not where the fields lay. Finding those plots would test whether the dense Aratu settlements were fed by nearby gardens, and could show how a village of around 2,000 people organized its labor on a savanna that textbooks rarely credit with large farming populations.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.