According to a study published in the journal Science Advances, corn cultivation was essential for the subsistence and development of large villages inhabiting the Cerrado – Brazil's savanna biome – between the 9th and 17th centuries. The research, led by archaeologists from the University of São Paulo and supported by FAPESP, reveals the subsistence strategies of these densely populated communities for the first time. They employed sophisticated land-use practices involving the cultivation of various species (polyculture), with a special emphasis on corn. Previously, scientists considered these communities to be either predominantly mobile hunter-gatherers or monoculture farmers.
In addition to contributing to our understanding of the history of human influence on one of the most biodiverse tropical savannas on the planet, the study sheds light on the food production and land use strategies that shaped the landscapes of the Cerrado as we know them today.
The study also highlights the importance of the biome in understanding the biotechnological innovations used by pre-colonial indigenous Brazilian societies, such as adapting corn to the environmental conditions of the Brazilian savanna, which differ greatly from the plant's place of origin. Previous research had already addressed the characterization and dispersal of corn in Latin America, showing that it arrived in Brazil via the southwestern Amazon rainforest at least 6,000 years ago. It originated in Mexico, where it first appeared 9,000 years ago, and was subsequently spread to other regions .
The conclusions of the study are based on the analysis of minute chemical variations preserved in human bones and teeth. This analysis made it possible to identify the types of plants and other foods consumed, providing a sort of "record" of diet throughout life.
"I often say that humans are what they eat, and that's recorded in the chemical composition of their bones and teeth. Through that, we were able to identify corn consumption comparable to that of Mayan or Andean populations – something completely unexpected in this context. We also detected variability between two distinct societies, that is, archaeological traditions with markedly different diets, corroborating social and cultural diversity," Eliane Chim, a researcher at the University of São Paulo's Museum of Archaeology and Ethnology (MAE-USP) and the lead author of the article, which is part of her doctoral dissertation, told Agência FAPESP.
"For over a century, Brazilian archaeology has debated the role of corn in pre-colonial societies, especially those with high population densities and more elaborate pottery. This is the first time that its central role in the subsistence of those populations has been demonstrated in Brazil. Just as in the Andes and Mesoamerica, corn cultivation here is associated with societies that had larger populations and left more evident marks on the landscape," notes André Strauss , project coordinator and Chim's advisor. Strauss is an archaeologist and a professor at MAE-USP and is one of the corresponding authors of the article, along with Patrick Roberts of the Max Planck Institute in Germany.
The researchers consider the study to be a milestone in Brazilian archaeology because it was published in a high-impact journal with Brazilian authors listed first and last. FAPESP funded the research through a Young Investigators grant awarded to Strauss, fellowships awarded to Chim and other group members ( 20/04402-0 , 23/06749-5 , 22/05420-7 , and 20/06729-6 ), and two projects, including one that funded publication in the journal ( 19/15914-4 and 26/12048-8 ).
The "value" of bones
The scientists analyzed the stable isotopes of carbon, nitrogen, and oxygen in the teeth and bones of more than 100 individuals from 37 archaeological sites in the Cerrado, Caatinga (a semi-arid biome in northeastern Brazil), and the Atlantic Forest. The samples, which date from a period between 1,100 and 400 years ago, were obtained from excavations conducted by the research group and from archaeological collections assembled since the 1970s.
Isotopes are natural variants of each chemical element that differ in the number of neutrons they contain. In the case of carbon, they indicate which types of plants predominated in the diet. For example, they can distinguish corn from other fruits and plants typical of the Cerrado. Nitrogen helps estimate the amount of animal protein consumed and the individuals' position in the food chain. Oxygen, on the other hand, provides data related to water consumption and environmental conditions.
Since different foods have distinct isotopic signatures, these signatures are "recorded" in body tissues and can be used to reconstruct the diets of ancient populations. This makes it possible to determine whether their diet was primarily based on corn or other foods and whether they consumed animal protein.
Additionally, the scientists performed radiocarbon dating on the collagen of approximately 40% of the bones that still contained protein. This technique determines the age of organic remains. The scientists also used paleoecological records to reconstruct the diets. These records consist of natural remains, such as seeds, sediments, and plant and animal remains, that provide insight into vegetation, climate, and the environment during different periods.
The samples come from the villages of two populations: the Aratu, who lived in the open, and the Una, one of the earliest pottery-making horticulturalists of the Cerrado, who frequented rock shelters, usually near riverbeds or ponds.
Among the Aratu populations, bone collagen and dental enamel from the oldest individuals revealed evidence of corn consumption. Additionally, other studies documented wear marks on ceramic vessels that are consistent with the fermentation of alcoholic beverages. This finding suggests a broader role for cultivated plants in the daily lives of these villages. These findings suggest that corn may have been a dietary staple and possibly used in communal or ritual practices.
"We don't hear much about them, but these Aratu groups had a unique presence in the Cerrado," Strauss points out. According to Strauss, Aratu villages had as many as 2,000 inhabitants, a population comparable to that of most European towns of the same era.
In contrast, the rock-shelter populations of the Una culture had a more diverse diet with lower corn intake. Since these groups occupied similar environments to those of the Aratu, the scientists conclude that the differences cannot be explained solely by ecology. Rather, they indicate that distinct cultural traditions and economic strategies coexisted within the biome. Both practiced polyculture, but corn was a primary source of subsistence for the more populous Aratu communities.
Collective effort
The project has been underway for more than ten years. It brought together 31 researchers from 10 Brazilian universities in collaboration with the Max Planck Society and institutions in Portugal, Poland, and the United States.
"Archaeology operates on a different timeline. You can't accomplish much in six months. You have to go into the field, excavate, return to the lab, and curate the finds. Only then can the analytical phase of the work begin. We also use this as a mechanism for training personnel, and Eliane [Chim] is a prime example of that," says Strauss.
For Chim, one of the challenges of conducting this type of study is preserving the archaeological material, especially when analyzing collagen. More than 270 artifacts were evaluated to obtain the sample used in the study.
"We intend to resume field research at those archaeological sites and try to locate the farmlands where people cultivated crops. We know the cemeteries, the urn fields, and the size of some villages, but we need to find the other areas occupied by those people," Chim adds, outlining the future of the research.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
