{"id":563118,"date":"2025-10-22T15:47:52","date_gmt":"2025-10-22T18:47:52","guid":{"rendered":"https:\/\/revistapesquisa.fapesp.br\/?p=563118"},"modified":"2025-10-22T15:47:52","modified_gmt":"2025-10-22T18:47:52","slug":"the-amazons-ancient-cornfields","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/the-amazons-ancient-cornfields\/","title":{"rendered":"The Amazon\u2019s ancient cornfields"},"content":{"rendered":"

Long before European contact, the Casarabe people inhabited vast stretches of the southwestern Amazon, from roughly 500 to 1400 C.E. A growing body of evidence suggests a sizable population once cultivated extensive maize fields across the Bolivian plains known as the Llanos de Moxos. And that is turning heads. Newly published research has reinterpreted these ancient farms as monocultures\u2014such as a January paper in Nature\u2014<\/em>and shed new light on the role of corn in ancient peoples\u2019 diets. Another article, from Nature Human Behaviour<\/em> in December, suggests these cornfields may have played a role in domesticating ducks.<\/p>\n

\u201cWe always thought pre-Columbian groups in this part of the Amazon grew a mix of crops\u2014like the \u201cthree sisters\u201d [corn, beans, and squash] of Central American agriculture, or used agroforestry systems,\u201d explains Italian environmental archaeologist Umberto Lombardo, from the Autonomous University of Barcelona. Lombardo led the Nature<\/em> study with collaborations from archaeologist Eduardo G\u00f3es Neves\u2019s group at the University of S\u00e3o Paulo\u2019s Museum of Archaeology and Ethnology (MAE-USP). \u201cDiscovering a monoculture of maize was truly a surprise,\u201d adds Lombardo, who has lived in the region for over two decades and has been doing fieldwork there since 2006.<\/p>\n

Earlier studies had already revealed that the region is dense with traces of ancient human habitation\u2014hundreds of monumental earthen mounds interconnected by canals and causeways. \u201cThey\u2019re arranged in a hierarchical layout, with larger mounds surrounded by clusters of smaller ones,\u201d says Lombardo. \u201cThat suggests a level of social complexity beyond isolated villages\u2014possibly even centralized political control,\u201d he adds.<\/p>\n\n \n \n \n <\/picture>Alexandre Affonso \/ Revista Pesquisa FAPESP<\/span>\n

Using a mix of remote sensing, microbotanical analysis, and field surveys, researchers have now uncovered sophisticated landscape engineering for farming: drainage canals to divert water during floods, and artificial ponds to store water through the dry season\u2014possibly even to attract animals for hunting. An analysis of ancient plant remains, such as phytoliths (the silica-based casts of plant cells, which are well preserved in the Llanos de Moxos), revealed that maize was abundant in fields and near ponds, but absent in forested zones\u2014clearly indicating that this was open-field farming rather than agroforestry.<\/p>\n

\u201cThere\u2019s been a decades-long debate about maize\u2019s role in the Amazon,\u201d says British archaeologist Jennifer Watling of MAE-USP, who supervised the postdoctoral research of Brazilian archaeobotanist Lautaro Hilbert, a coauthor on the study. Much of that uncertainty came from the belief that maize requires fertile soils\u2014thought to be rare in the Amazon. But that notion has been overturned by discoveries of dark earths, which are still being intentionally produced by Indigenous communities today.<\/p>\n

On a smaller scale, Watling and her team also found phytoliths from squash, cassava, gourd, and other cultivated plants within forested areas. \u201cOn higher ground that stays dry during the rainy season, there are forest areas that were likely under human management,\u201d she notes. Watling says the Nature<\/em> study underscores just how central maize was to the diet of these ancient communities. The same is true for the December article in Nature Human Behaviour<\/em>, led by Brazilian archaeologist Tiago Hermenegildo, who analyzed material from the Llanos de Moxos for his PhD, completed in 2022 at the University of Cambridge, with funding from the Brazilian National Council for Scientific and Technological Development (CNPq). The material has since been repatriated and is now housed at a museum in Trinidad, Bolivia\u2014established using European research funds as a gesture of reciprocity.<\/p>\n

\u201cThere\u2019s substantial evidence of maize at the site,\u201d says Hermenegildo. \u201cWe\u2019re finding traces in the pottery, in the soils, and in preserved bits of kernels and cobs.\u201d Such finds often hinge on chance\u2014what happens to be preserved over time and whether it happens to show up in the sediment samples archaeologists have sieved. To get around that reliance on chance, Hermenegildo has focused since his master\u2019s degree on analysis of stable isotopes\u2014forms of atoms that, unlike radioactive ones, don\u2019t decay over time.<\/p>\n

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Education Images \/ Universal Images Group via Getty Images<\/span>Cornfields in the Peruvian Amazon: in some regions, native varieties of maize can still be foundEducation Images \/ Universal Images Group via Getty Images<\/span><\/p><\/div>\n

Diet recorded in collagen
\n<\/strong>\u201cThe carbon isotopes preserved in bone collagen tell us which plants people were eating, while nitrogen isotopes are associated with animal protein intake,\u201d Hermenegildo explains. He notes that edible C4 plants such as maize, with its four-carbon photosynthetic pathway, do not occur naturally in the Amazon. When C4-type carbon shows up in human or animal bones, it is a strong indicator of maize in the diet.<\/p>\n

Watling, who is not herself a specialist in stable isotope analysis, still sees it as a more informative tool for inferring diets, as it captures what people and animals consumed over their lifetimes. But the broader archaeological context still matters. Hermenegildo agrees: before analyzing isotopic data, it is important to have a clear picture of the site\u2019s zooarchaeological and archaeobotanical record\u2014what animals and plants were present in that human context. \u201cWe started turning up a surprising number of duck bones while analyzing the animal remains,\u201d he recalls. That was unexpected\u2014and it led to a new interpretation.<\/p>\n

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Umberto Lombardo\u2009\/\u2009Universidade Aut\u00f2noma de Barcelona<\/span>Pre-Columbian ponds were used to store water for irrigationUmberto Lombardo\u2009\/\u2009Universidade Aut\u00f2noma de Barcelona<\/span><\/p><\/div>\n

The study provided the first archaeological evidence suggesting that the Muscovy duck (Cairina moschata<\/em>), a species native to the area, may be the only known case of animal domestication east of the Andes. \u201cStable isotopes showed that the ducks were eating an even higher proportion of maize than people were,\u201d Hermenegildo says. He adds, however, that the ducks were likely used in rituals\u2014something also noted in accounts left by Jesuit missionaries who passed through the area in the sixteenth and seventeenth centuries. \u201cWe still don\u2019t know exactly on what occasions and how often people were eating ducks,\u201d he cautions. Stable isotope analysis is unable to pinpoint specific sources of animal protein, Hermenegildo explains\u2014but most of the animal bones recovered from the site belong to deer. These animals, which could weigh up to 40 kilograms (about 88 pounds), were hunted and likely offered a more significant source of meat for the community.<\/p>\n

For Hermenegildo, the key finding is that maize was central to the pre-Columbian diet in this region\u2014and an anchor crop around which early urban centers developed. He points to evidence of a trade network between the Amazon lowlands and the Andes, with copper tools and ornaments showing up at archaeological sites in the Llanos de Moxos. Maize eventually spread into the mountains too, though it remains unclear which route it took to get there. \u201cIt took longer for maize to adapt to high-altitude environments,\u201d he explains. After European colonization, Indigenous Amazonian populations were decimated\u2014and so were records of maize, a crop that relies on human cultivation to thrive.<\/p>\n

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Dan Vickers | Heiko Pr\u00fcmers \/ Instituto Arqueol\u00f3gico Alem\u00e3o<\/span>Archaeological digs (left<\/em>) have uncovered bones from the Muscovy duck\u2014the only known locally domesticated animal east of the Andes (right<\/em>)Dan Vickers | Heiko Pr\u00fcmers \/ Instituto Arqueol\u00f3gico Alem\u00e3o<\/span><\/p><\/div>\n

\u201cThe southwestern Amazon is a major hotspot of maize diversity\u2014where native landraces were developed and adapted over time,\u201d says Flaviane Costa, a postdoctoral genetics researcher at the University of Oxford, who was not involved in the studies. Costa, who specializes in maize domestication and the traditional landraces still grown in the Amazon today, says that a better understanding of this agricultural, genetic, and cultural heritage can be highly valuable, even in shaping modern conservation and food security policy.<\/p>\n

Costa believes it is important to build further on the research by Hermenegildo, Lombardo, and collaborators to better gauge the scale of Casarabe agriculture and how it compares with the farming systems Indigenous peoples use today. She also urges caution when labeling the Casarabe fields as \u201cmonocultures.\u201d \u201cTraditional maize cropping systems are very dynamic,\u201d she explains. \u201cThey preserve a wide range of native landraces with diverse traits, making them suitable for many different uses.\u201d Lombardo notes that the findings in Bolivia point to the possibility of large-scale food production\u2014enough to support a sizable population\u2014but this is still speculative. \u201cWe still need a comprehensive map of all the ponds and canals to estimate total agricultural output,\u201d he says. \u201cOnly then can we start modeling the size of the population.\u201d<\/p>\n

The hurdles to isotope research in archaeology
\n<\/strong>High costs, limited access, and ethical issues continue to slow broader use<\/p>\n

Tiago Hermenegildo earned his master\u2019s degree in 2009 at the Center for Nuclear Energy in Agriculture (CENA) at USP\u2019s Luiz de Queiroz School of Agriculture (ESALQ-USP). \u201cI chose it for its expertise in stable isotope analysis\u2014but at the time, no one there was applying it to archaeology,\u201d he recalls.<\/p>\n

Even today, stable isotope analysis remains incipient in Brazil, largely due to a lack of investment, says Portuguese anthropologist Maria Ana Correia, a researcher at Portugal\u2019s Interdisciplinary Center for Archaeology and the Evolution of Human Behavior, and an affiliate of the Laboratory of Archaeology and Environmental and Evolutionary Anthropology at USP. She adds that preserving collagen\u2014the basis for isotope testing\u2014is often difficult at Brazilian sites due to the region\u2019s heat and humidity.<\/p>\n

Correia coauthored a January article in the American Journal of Biological Anthropology<\/em> outlining ethical guidelines that need to be observed in this type of research. \u201cWe have to be selective with archaeological samples,\u201d she recommends. \u201cPreservation is critical for future research\u2014we don\u2019t yet know what new techniques might emerge\u2014and the entire process should be thoroughly documented. And just as important, we need to establish responsible relationships with society\u2014particularly with the present-day descendants of the communities we\u2019re researching.\u201d For Correia, it is particularly encouraging that these recent studies are being led by Latin American scholars.<\/div>\n

Projects<\/strong>
\nIndigenous peoples and the environment in the Ancient Amazon<\/em> (n\u00ba 19\/07794-9<\/a>);\u00a0Principal Investigator<\/strong>\u00a0Eduardo G\u00f3es Neves (USP);Grant Mechanism<\/strong>\u00a0Thematic Project;\u00a0Agreement<\/strong>\u00a0AHRC, UKRI;\u00a0Investment<\/strong>\u00a0R$2,732,154.84.<\/p>\n

Scientific articles<\/strong>
\nHERMENEGILDO, T.\u00a0et al<\/em>.\u00a0Stable isotope evidence for pre-colonial maize agriculture and animal management in the Bolivian Amazon<\/a>.\u00a0Nature Human Behaviour<\/strong>. Dec. 23, 2024.
\nLOMBARDO, U.\u00a0et al.<\/em>\u00a0Maize monoculture supported pre-Columbian urbanism in southwestern Amazonia<\/a>.\u00a0Nature<\/strong>. Jan. 29, 2025.
\nSTANTIS, C.\u00a0et al<\/em>.\u00a0Ethics and applications of isotope analysis in archaeology<\/a>.\u00a0American Journal of Biological Anthropology<\/strong>. Vol. 186, no. 1, e24992. Jan. 2025.<\/p>\n","protected":false},"excerpt":{"rendered":"Archaeological sites in Bolivia reveal traces of large-scale corn farming that once sustained a dense human population\u2014and may have even played a role in domesticating ducks","protected":false},"author":3,"featured_media":563119,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[159],"tags":[202,259,199],"coauthors":[1601],"class_list":["post-563118","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science","tag-archaeology","tag-chemistry","tag-farming","position_at_home-sumario"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/563118","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=563118"}],"version-history":[{"count":1,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/563118\/revisions"}],"predecessor-version":[{"id":563143,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/563118\/revisions\/563143"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/563119"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=563118"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=563118"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=563118"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=563118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}