Researchers have tested ancient DNA from corn found at archaeological sites in Arkansas, shedding new light on the dispersal of one of the world’s most important food crops.
By reconstructing the genomes of archaeological maize cobs and kernels, the study, by researchers at the University of York and the University of Copenhagen, revealed that 1,000-year-old maize from rockshelters in the Ozark region of Arkansas, US, shares a close genetic link with modern Northern Flint varieties.
These hardy varieties are cold-adapted and are the ancestors for commercially important maize grown around the world. Researchers say that understanding its origins and journey through different geographical regions could help find new ways of sustaining and improving crops today, as pressures on global food supply increases and crop health is challenged by climate change.
Researchers showed that maize underwent selection as it was transported from the US Southwest across the Great Plains, particularly through a gene, known as waxy1. Genetic variants in the waxy1 gene affect the stickiness and chewiness of maize, traits that are still valued in some traditional cuisines today.
This suggests that farmers 1,000 years ago were not just engaged in planting and harvesting, but in selecting traits that could help in breeding and producing the best quality yield for food, not too dissimilar to farmers today.
Dr Nathan Wales, from the University of York’s Department of Archaeology, said: “We know that maize was domesticated in Mexico, but it has long been debated what route it took to regions of the US to become what it is today - one of the most globally important food crops.
“We now have a clearer idea of the journey it took from Mexico, and we better appreciate how regional varieties can become more globally significant than varieties grown near the domestication centre. It is valuable information for crop breeders because they can chart the evolution of the crop, reintroduce any lost genetic diversity or develop new varieties, which could be vital to helping food shortages in the future.”
Ancient maize genomes from the Ozark rockshelters indicated that maize entered eastern North America at least twice, tracing ancestry to both the upland US Southwest and southern Texas.
Dr Jazmín Ramos-Madrigal, from the Globe Institute at the University of Copenhagen in Denmark, said: “We also showed that maize could only be introduced into eastern North America once humans bred local varieties with the genetic tools to cope with the challenging environment of the region, which goes someway to demonstrating the skills and knowledge of farmers 1,000 years ago.”
A University of Arizona-led study sheds light on how long humans in the Americas have had relationships with the ancestors of today's dogs – and asks an "existential question": What is a dog?
François Lanoë, an assistant research professor in the U of A School of Anthropology, after helping unearth this 8,100-year-old canine jawbone in interior Alaska in June 2023. The bone, along with a 12,000-year-old leg bone discovered at a nearby site, are some of the earliest evidence that ancient dogs and wolves formed close relationships with people in the Americas.
"Dog is man's best friend" may be an ancient cliché, but when that friendship began is a longstanding question among scientists.
A new study led by a University of Arizona researcher is one step closer to an answer on how Indigenous people in the Americas interacted with early dogs and wolves.
The study, published today in the journal Science Advances and based on archaeological remains from Alaska, shows that people and the ancestors of today's dogs began forming close relationships as early as 12,000 years ago – about 2,000 years earlier than previously recorded in the Americas.
"People like me who are interested in the peopling of the Americas are very interested in knowing if those first Americans came with dogs," Lanoë added. "Until you find those animals in archaeological sites, we can speculate about it, but it's hard to prove one way or another. So, this is a significant contribution."
Lanoë and his colleagues unearthed a tibia, or lower-leg bone, of an adult canine in 2018 at a longstanding archeological site in Alaska called Swan Point, about 70 miles southeast of Fairbanks. Radiocarbon dating showed that the canine was alive about 12,000 years ago, near the end of the Ice Age.
Another excavation by the researchers in June 2023 – of an 8,100-year-old canine jawbone at a nearby site called Hollembaek Hill, south of Delta Junction – also shows signs of possible domestication.
The smoking gun? A belly of fish
Chemical analyses of both bones found substantial contributions from salmon proteins, meaning the canine had regularly eaten the fish. This was not typical of canines in the area during that time, as they hunted land animals almost exclusively. The most likely explanation for salmon showing up in the animal's diet? Dependence on humans.
"This is the smoking gun because they're not really going after salmon in the wild," said study co-author Ben Potter, an archaeologist with the University of Alaska Fairbanks.
The researchers are confident that the Swan Point canine helps establish the earliest known close relationships between humans and canines in the Americas. But it's too early to say whether the discovery is the earliest domesticated dog in the Americas.
That is why the study is valuable, Potter said: "It asks the existential question, what is a dog?"
The Swan Point and Hollembaek Hill specimens may be too old to be genetically related to other known, more recent dog populations, Lanoë said.
"Behaviorally, they seem to be like dogs, as they ate salmon provided by people," Lanoë said, "but genetically, they're not related to anything we know."
He noted that they could have been tamed wolves rather than fully domesticated dogs.
'We still had our companions'
The study represents another chapter in a longstanding partnership with tribal communities in Alaska's Tanana Valley, where archaeologists have worked since the 1930s, said study co-author Josh Reuther, an archaeologist with the University of Alaska Museum of the North.
Researchers regularly present their plans to the Healy Lake Village Council, which represents the Mendas Cha'ag people indigenous to the area, before undertaking studies, including this one. The council also authorized the genetic testing of the study's new specimens.
Evelynn Combs, a Healy Lake member, grew up in the Tanana Valley, exploring dig sites as a kid and taking in what she learned from archaeologists. She's known Lanoë, Potter and Reuther since she was a teenager. Now an archaeologist herself, Combs works for the tribe's cultural preservation office.
"It is little – but it is profound – to get the proper permission and to respect those who live on that land," Combs said.
Healy Lake members, Combs said, have long considered their dogs to be mystic companions. Today, nearly every resident in her village, she said, is closely bonded to one dog. Combs spent her childhood exploring her village alongside Rosebud, a Labrador retriever mix.
"I really like the idea that, in the record, however long ago, it is a repeatable cultural experience that I have this relationship and this level of love with my dog," she said. "I know that throughout history, these relationships have always been present. I really love that we can look at the record and see that thousands of years ago, we still had our companions."
An artist’s reconstruction of Clovis life 13,000 years ago shows the Anzick-1 infant with his mother consuming mammoth meat near a hearth. Another individual crafts tools, including dart projectile points and atlatls. A mammoth butchery area is visible nearby. The scene is inspired by the La Prele mammoth site in Wyoming and set against the Montana landscape where the Anzick burial was discovered.
Credit: Artist Eric Carlson created the scene in collaboration with archaeologists Ben Potter (UAF) and Jim Chatters (McMaster University).
Scientists have uncovered the first direct evidence that ancient Americans relied primarily on mammoth and other large animals for food. Their research sheds new light on both the rapid expansion of humans throughout the Americas and the extinction of large ice age mammals.
The study, featured on the Dec. 4 cover of the journal Science Advances, used stable isotope analysis to model the diet of the mother of an infant discovered at a 13,000-year-old Clovis burial site in Montana. Before this study, prehistoric diet was inferred by analyzing secondary evidence, such as stone tools or the preserved remains of prey animals.
The findings support the hypothesis that Clovis people specialized in hunting large animals rather than primarily foraging for smaller animals and plants.
The Clovis people inhabited North America around 13,000 years ago. During that time period, animals like mammoths lived across both northern Asia and the Americas. They migrated long distances, which made them a reliable fat- and protein-rich resource for highly mobile humans.
“The focus on mammoths helps explain how Clovis people could spread throughout North America and into South America in just a few hundred years,” said co-lead author James Chatters of McMaster University.
“What's striking to me is that this confirms a lot of data from other sites. For example, the animal parts left at Clovis sites are dominated by megafauna, and the projectile points are large, affixed to darts, which were efficient distance weapons,” said co-lead author Ben Potter, an archaeology professor at the University of Alaska Fairbanks.
Hunting mammoths provided a flexible way of life, Potter said. It allowed the Clovis people to move into new areas without having to rely on smaller, localized game, which could vary significantly from one region to the next.
“This mobility aligns with what we see in Clovis technology and settlement patterns,” Potter said. “They were highly mobile. They transported resources like toolstone over hundreds of miles.”
Researchers were able to model the Clovis people’s diet by first analyzing isotopic data published during earlier studies by other researchers of the remains ofAnzick-1, an 18-month-old Clovis child. By adjusting for nursing, they were able to estimate values for his mother’s diet.
“Isotopes provide a chemical fingerprint of a consumer's diet and can be compared with those from potential diet items to estimate the proportional contribution of different diet items,” said Mat Wooller, an author on the study and director of the Alaska Stable Isotope facility at UAF.
The team compared the mother’s stable isotopic fingerprint to those from a wide variety of food sources from the same time period and region. They found that about 40% of her diet came from mammoth, with other large animals like elk and bison making up the rest. Small mammals, sometimes thought to have been an important food source, played a very minor role in her diet.
Finally, the scientists compared the mother’s diet to those of other omnivores and carnivores from the same time period, including American lions, bears and wolves. The mother’s diet was most similar to that of the scimitar cat, a mammoth specialist.
Findings also suggest that early humans may have contributed to the extinction of large ice age animals, especially as environmental changes reduced their habitats.
“If the climate is changing in a way that reduces the suitable habitat for some of these megafauna, then it makes them potentially more susceptible to human predation. These people were very effective hunters,” said Potter.
“You had the combination of a highly sophisticated hunting culture — with skills honed over 10,000 years in Eurasia — meeting naïve populations of megafauna under environmental stress,” said Chatters.
An important aspect of this research, according to Potter and Chatters, is their outreach to Native Americans in Montana and Wyoming about their concerns and interest in this work.
"It is important and ethical to consult with Indigenous peoples on questions relating to their heritage," they said.
They worked with Shane Doyle, executive director of Yellowstone Peoples, who reached out to numerous tribal government representatives throughout Montana, Wyoming and Idaho. “The response has been one of appreciative consideration and inclusion,” said Doyle.
"I congratulate the team for their astounding discovery about the lifeways of Clovis-era Native people and thank them for being tribally inclusive and respectful throughout their research,” he said. “This study reshapes our understanding of how Indigenous people across America thrived by hunting one of the most dangerous and dominant animals of the day, the mammoth."
Other authors of the paper include Stuart J. Fiedel, independent researcher; Juliet E. Morrow, University of Arkansas; and Christopher N. Jass, Royal Alberta Museum.
Anyone who has taken an interest in research at the Department of Egyptology at Julius Maximilian University Würzburg (JMU) in the past will be familiar with the name “Soknopaiou Nesos.” This ancient settlement in the so-called “Fayum Basin,” with its temple complex, attracted the interest of Würzburg scholars at an early stage.
The former chair Karl-Theodor Zauzich was a pioneer here, being the first to edit documents from the site in 1968. He repeatedly told this anecdote: As experienced a demotist as he was, he began to doubt himself, claiming that while these texts were obviously written in demotic, he did not understand anything at first.
“Demotic” refers to both a stage and a written form of ancient Egyptian, which was in use from around the seventh century BC to the fifth century AD. Demotic, which is difficult to read, has the reputation for being “the most evil of all evil Egyptian scripts” - as the Egyptologist Hermann Grapow put it in 1937. Apparently, the Demotic scribes of Soknopaiu Nesos succeeded in replicating this trend.
Who is fearing the most evil of Egypt's evil writings?
The current chair and Zauzich’s successor, Professor Martin A. Stadler, can now advance this work after completing two research projects on Soknopaiu Nesos under his leadership. The German Research Foundation (DFG) has granted approximately one million euros for an package proposal to develop this research in three projects over the coming years.
Stadler already attempted to obtain funding from the DFG for a twelve-year, long-term project in 2008. At that time, however, the DFG reviewers did not believe that he had enough material for it. He then acquired a six-year and a three-year project. “After completing my two previous projects over a total of nine years, we are now going to complete the twelve years I originally planned – and this with an interdisciplinary team,” Stadler states happily.
“In the village of Soknopaiou Nesos one of the largest and most comprehensive papyrus corpora for the study of local writing practices has been found,” says Martin Stadler, explaining the background to this research project. Despite the mass of evidence, or perhaps precisely because of it, this material has only ever been systematically processed in part, according to the Egyptologist. The project participants want to make progress in the coming years. They can build on a large number of papyri that have already been identified and published. However, they also need to edit further texts for the first time in order to obtain a more comprehensive picture.
What are these texts? They date from the period between the 2nd century BCE and the early 3rd century CE. They include religious texts, receipts and accounts by, or relating to, temple staff, Greek documents documenting communication between the temple staff or the head of the temple and the Roman authorities, as well as texts belonging to family or professional archives. They are written partly in demotic and partly in Greek.
A Ptolemaic temple archive from Soknopaiu Nesos
The first sub-project focuses on demotic and Greek documentary texts from the temple archive and their relationship to each other. Here, demotist Carolin Arlt wants to find out who wrote the texts for whom, in which language and for what purpose, and what similarities they have. “Most of the texts were written by the same scribe, a certain Tesenuphis, son of Marres, ‘scribe of the priests’,” explains Carolin Arlt. By these sources, it will be possible to examine the important scribal office in more detail and find out what tasks the scribe had, what kind of texts he wrote and in what other ways he was involved in the affairs of the temple.
Greek writing practice in Soknopaiu Nesos
The notary’s office, the so-called grapheion, and the archives of the site are the focus of the second sub-project, in which Bianca Borrelli, a specialist in Greek papyri, will be conducting research. “The grapheion can be seen as the institution that helped to create a kind of mediation between Greek and Egyptian cultural traditions,” explains Borrelli. The aim is to shed light on the relationship between the Grapheion and the temple, as well as its role in the larger legal and administrative institutions of the Ptolemaic and Roman states.
180 documents form the core of this study, in addition to internal grapheion documents, texts from related institutions and other sources known or suspected to have been written by notaries. The results should contribute to a better understanding of the importance of the Greek language in Egypt from the Ptolemaic to the Roman imperial period.
Economy and cult: the cult business for the crocodile god Soknopaios
Demotic and Greek accounting scrolls from Soknopaiou Nesos form the research focus of the third sub-project. The aim is to include as many examples of different types of reckoning as possible in order to better understand the internal temple administration. “One focus will be on the transition between demotic and Greek accounting to determine whether there is significant evidence of internal Greek accounting from the temple of Soknopaios and when and how this possible transition took place,” says Marcel Moser, who is working on the project as a doctoral researcher.
Stadler himself is deciphering religious texts that have not been read for 2000 years. “These works make it clear how interesting Soknopaiou Nesos is from a general Egyptological perspective, beyond the pure framework of demotic studies,” he says. After all, the last manuscript sources for certain cult texts can be found there.
The cult cost money, for which the temple needed income. In this respect, the temple was a cult business. Soknopaiou Nesos now offers the unique opportunity to study two important aspects of the same institution, the ritual and economic sides of the temple, using sources in two different languages. This is so fascinating that the project participants are not even deterred by the most evil of all evil Egyptian writings.
Preliminary findings from the research have been published in the monograph Between the Land and the Sea: On Villae Maritimae in the Roman West, edited by Scienze e Lettere (Rome) in 2024
The Sant Gregori villa is situated approximately 75 meters from Burriana’s coastline, making it a maritime villa. Its constructions date from the turn of the era to the 4th century CE. Spanning over 15,000 m², the site includes various spaces such as production structures, storage facilities, heated rooms for baths, and residential areas. Its size exceeds the average of coastal villas excavated in the Roman province of Tarraconensis, which typically surpass 10,000 m².
Excavations at the Sant Gregori site in Burriana have revealed that this maritime villa specialized in viticulture. The research team, coordinated by the Mediterranean Archaeology Partnership Programme at the Universitat Jaume I of Castelló (UJI), in collaboration with the Archaeological Museum of Burriana, has identified structures for wine production (cella vinaria) and agricultural plots dedicated to viticulture (fundus). Due to the significance of these findings, the Burriana City Council and the Archaeological Museum are working to include these areas in the site’s musealization and enhancement project.
While no pressing rooms (torculares) have been found so far, storage areas and additional adjacent spaces, possibly for work and living quarters, have been uncovered. These buildings are isolated and follow an east-west orientation, protecting them from northern humidity and excessive southern sunlight. Archaeological evidence of vineyard cultivation has also been identified, specifically planting trenches (a type of planting referred to as sulcus by Columella and Pliny), associated with structures related to winemaking, such as remnants of a large storage facility.
In Roman Hispania, remains of storage facilities are relatively common, but planting trenches with evidence of vine cultivation have been found in only a few locations, such as the Galician coast, Badajoz, the Bay of Cádiz, and Huelva. At Sant Gregori, ten parallel trenches in excellent condition have been documented, aligned northeast-southwest. These trenches form continuous rows, allowing for the planting of multiple vines within them. Their average width ranges from 1.1 to 1.3 meters, with 2.5 to 3 meters between rows.
One intriguing aspect is the location of the Sant Gregori vineyard—an open, sunny area near a swampy zone (palus). Ancient writers Columella and Pliny noted that, in antiquity, the Pontine Marshes and the wetlands of Ravenna in Italy produced thriving vineyards thanks to drainage operations. Preliminary findings from the research have been published in the monograph Between the Land and the Sea: On Villae Maritimae in the Roman West, edited by Scienze e Lettere (Rome) in 2024.
The Sant Gregori villa is situated approximately 75 meters from Burriana’s coastline, making it a maritime villa. Its constructions date from the turn of the era to the 4th century CE. Spanning over 15,000 m², the site includes various spaces such as production structures, storage facilities, heated rooms for baths, and residential areas. Its size exceeds the average of coastal villas excavated in the Roman province of Tarraconensis, which typically surpass 10,000 m².
In Roman times, the area where the villa is located was linked to the Roman municipality of Saguntum. Findings from various archaeological excavations indicate that large agricultural estates were planned on the flatlands, focusing on vine cultivation and wine production. In Saguntum, wine commerce reportedly became significant during Emperor Augustus’s reign and continued until at least the 2nd century CE. Latin literature from the 2nd century CE, particularly texts by Fronto and Juvenal, suggests that Saguntine wine was fairly popular in Rome during this period.
Household utensils or objects for ritual use, gourds are present in various cultural environments in Brazil, especially in indigenous or riverside communities, but also in large cities in the Amazon region, such as Belém, capital of the state of Pará. “Gourds are believed to be among the first cultivated plants in the Amazon, and their use is probably even older than that of ceramics,” says researcher Renata Maria de Almeida Martins, professor at the Faculty of Architecture and Urbanism of the University of São Paulo (FAU-USP), in Brazil, and coordinator of Labya-Yala – the Decolonial Studies Laboratory – and the project “Barroco-açu: Portuguese America in the Artistic Geography of the Global South”, which received a FAPESP research grant in the Young Investigators – Phase 2 modality.
As part of the project, Martins conducted a detailed analysis of the production of varnished gourds and calabashes in the 18th-century captaincy of colonial Brazil, called Grão-Pará. These objects are preserved in museums in Portugal. An article on this subject was published in the journal Heritage.
“The gourds were made by Indigenous women who used sophisticated techniques to create a black, shiny and durable finish, like an ‘Amazonian lacquer.’ These fruits had their iconographic fields modified and were refashioned by decorations with motifs inspired by the local flora and fauna, but also by patterns for European and Asian embroidery, which circulated worldwide, reflecting the artistic exchanges of the time, as also happened with objects covered with mopa-mopa, also called Barniz de Pasto, in Colombia, or with maque, the Mexican lacquer,” says Martins.
It is important to note that these gourds were not made spontaneously and randomly, but were produced in manufactories maintained by settlers or within the framework of religious missions in the Amazon. The craft of gourd painting was recognized at the beginning of the 18th century. The products of these “factories” were mostly destined for the European market, participating in a process of globalization that was already underway at the time.
The refashioned gourds were produced mainly in the village of Monte Alegre (formerly the indigenous village of Gurupatuba, now Monte Alegre, in the state of Pará), in other places in the Lower Amazon region, and also in Belém, the capital of Grão-Pará. The naturalist Alexandre Rodrigues Ferreira (1756-1815) collected several of them in his Philosophical Journey, which are now in the collections of the Maynense Museum of the Lisbon Academy of Sciences and the Science Museum of the University of Coimbra. In his account, Ferreira states that between 5,000 and 6,000 gourds were produced each year in the village of Monte Alegre, most of which were sent to Lisbon. “Their varied and complex decorations, based on Indigenous traditions and/or with Asian and European inspirations, are examples that show the creative and artistic practices of resistance of Indigenous, African and mestizo women,” says Martins.
In addition to studying 18th-century gourds, in 2023 the researcher visited the community of Carapanatuba, in the Aritapera region, in the municipality of Santarém, in the Lower Amazon, where these objects are still produced, now by free and empowered women from the riverside region. The Association of Santarém Riverside Craftswomen (Asarisan), founded in 2003, has brought together artists from the five communities of Aritapera and has played a key role in ensuring that the “Way of Making Gourds from the Lower Amazon” was included in the Register of Knowledge of the National Institute of Historical and Artistic Heritage (IPHAN), as part of Brazil’s Cultural Heritage, in 2015.
“I found, as other scholars have also reported, that, for the most part, production still follows the same process described by Ferreira. Women like Lélia Maduro, Silvane Maduro, Marinalva Correia, Francisca Pereira, Socorro Pereira and others from the communities in the Aritapera region preserve the ancestral knowledge about nature, the rivers, the plants and the local animals. As well as the long process of preparing gourds varnished with cumatê and 'embroidered' with incisions,” says Martins.
In the garden around the house of Dona (“Mistress”) Lélia and her husband, Senhor (“Mister”) Antônio, there are different types of gourd trees (Crescentia cujete), which produce round or oval fruits of different sizes. The women pick them when they are ripe: when they make a certain sound.
The fruits are then cut open with a machete or saw, and the resulting gourds are placed in a large pot of boiling water to soften the shells. Then, the outer shell of each gourd is carefully scraped with a blade, the edge is smoothed with the rough tongue of the pirarucu fish (Arapaima gigas) and the inside with the scales of the same fish. The final preparation for the application of the varnish is done by rubbing the inside and outside with the large leaves of the embaúba tree (Cecropia), a species also found in the area near the family’s home. The treated but unvarnished gourd is called “pitinga.”
The “lacquering” process is done by applying tincture of cumatê, a reddish liquid obtained by infusing the bark of another tree of the region, the cumatezeiro (Myrcia atramentifera). After being painted with several layers of dye, the gourds are placed on a bed of sand or ashes, sprinkled with human urine and left covered for an entire night. The chemical reaction between the components of the dye and the urine transforms the reddish dye into a kind of shiny black “lacquer.” This technique, developed by Indigenous women of the Lower Amazon, produces a result comparable to and even superior to the best lacquer from China (Rhus vernicifera or Rhus verniciflua), according to reports from the 18th century.
“After all these steps, the gourds are decorated by making incisions with a small knife. The incision removes the varnish and allows the light background to shine through. Painting by applying vegetable or mineral dyes to the bare surface, which was widely used on gourds in the 18th century, is hardly used in the region today, although the dye-producing plants are known to the riverside artists,” says Martins.
The iconography of Indigenous origin, consisting of geometric and abstract motifs, is increasingly used in today’s gourds, which are produced for use or trade. “However, even in colonial times, the production of gourds, in addition to serving the export market, also had important functions in the ritual context. In his memoirs, Ferreira recounted the resistance of the Indigenous women of Monte Alegre to selling certain gourds, which had beads and muiraquitãs (a kind of Amazonian amulet), because of their sensitive meanings in the social relations of the communities,” explains Martins.
Produced by women, gourds are also symbolically associated with fertility, creation myths, and the ancient healing practices of Indigenous peoples, and are still widely used today to prepare and pour therapeutic baths and blessings, as well as to serve typical Amazonian foods such as tacacá.
In the 18th century, however, the workshops set up in the villages and religious missions redirected this ancestral tradition to cater for the European market, which was hungry for luxury items as well as objects considered “exotic.” Asian or Asian-inspired European pieces, such as porcelain, silk, embroidery, and even ivory crucifixes, served as models for locally produced objects that reinterpreted the imported ones. “Indigenous and Afro-Indigenous artists used techniques such as inlaying, marquetry, and gilding, adapting Amazonian materials and plants such as copaiba (Copaifera langsdorffii) and West Indian locust (Hymenaea courbaril), for example, to create effects similar to the gilding found on Asian objects. The participation of Indigenous women, their intimacy with the nature of the forest, was fundamental in this process. This contribution and protagonism, which is often made invisible, is essential for understanding the complexity of cultural and artistic relations in the Amazon, in colonial times and today,” concludes Martin
Archeological samples of grains, straw and cobs collected from caves in Peruaçu Valley have primitive traits resembling those of the ancestral plant originally from Mexico, where the domestication process is believed to have begun some 9,000 years ago.
Brazilian scientists have determined that ancient specimens of partially domesticated maize (Zea mays, also known as corn) originally from Peruaçu Valley in Minas Gerais state (Brazil) were the farthest from Mexico, the plant’s historic center of origin, of any finds made so far. An article describing their research is published in the journal Science Advances. The study was led by researchers affiliated with the University of São Paulo (USP) and EMBRAPA, the Brazilian Agricultural Research Corporation.
The findings reinforce the theory, based on genetic evidence from plants alive now, that domestication of maize may also have been completed in South America, as proposed in an article published in 2018 in the journal Science.
The samples of partially domesticated maize analyzed in the study include cobs, straw and grains from digs conducted in Peruaçu Valley in 1994 by archeologists affiliated with the Federal University of Minas Gerais (UFMG).
“These samples were initially considered specimens of domesticated maize that had failed to grow sufficiently. However, in light of genetic evidence that the final domestication process may have occurred in South America, we analyzed the material again and found several traits shared with the ancestral plant from which maize originated in Mexico 9,000 years ago and that arrived in southwestern Amazonia 6,000 years ago,” said Flaviane Malaquias Costa, first author of the Science Advances article, which reports a study conducted while she was a PhD candidate and postdoctoral researcher at Luiz de Queiroz College of Agriculture (ESALQ-USP). The study was supported by FAPESP, the National Council for Scientific and Technological Development (CNPq, a Brazilian government agency), and the Scientific Research Commission at Uruguay’s University of the Republic (CSIC-UDELAR).
Peruaçu Valley is some 7,150 km from Mexico. The distance from the North American country to southwestern Amazonia, where today’s Brazilian states of Rondônia and Acre are located, is about 2,300 km. The samples are the farthest from the plant’s center of origin ever found with primitive characteristics.
Although archeological evidence points to the presence of human populations in Peruaçu Valley between 10,000 and 9,000 years ago, maize appears to have arrived in the region only some 1,500 years ago. The semi-domesticated samples found there were dated to between 1,010 and 500 years ago, a period largely prior to the arrival of Europeans in South America.
“This shows the importance of past Indigenous communities in selecting, managing and fixing traits that gave rise to today’s South American maize races [local varieties]. Their descendants continue to do so even now, contributing to the maintenance of our genetic resources,” said Fábio de Oliveira Freitas, penultimate author of the article and a researcher at EMBRAPA Genetic Resources and Biotechnology in Brasília.
By analyzing the specimens from caves in Peruaçu Valley, the researchers were able to determine that they were closely related to the Entrelaçado race present in Rondônia and Acre. “This is one of the races that originated in South America via selection of other populations. We found extant varieties of it during our research project in several locations in Brazil and Uruguay,” said Elizabeth Ann Veasey, a co-author of the article and a professor at ESALQ-USP. She was Costa’s doctoral thesis advisor and principal investigator for a project on maize domestication supported by FAPESP.
Ancestral rows
To distinguish between domesticated and semi-domesticated specimens, the researchers analyzed a number of morphological traits that helped determine their distance from the wild plant, which is known as teosinte.
One of these marker traits is the number of grain rows, with under eight being considered typical of primitive teosinte, a wild grass native to Mexico and first domesticated some 9,000 years ago.
Modern maize races grown in lowland areas of South America have between eight and 26 rows per ear, whereas the archeological samples from Peruaçu Valley have between four and six rows. The researchers analyzed 296 samples, including cobs, straw and grains.
“We traveled from the remote past to the present, from archeological remains to the extant races and varieties that are still being diversified by traditional peoples, who are the protagonists of this story,” Costa said.
The samples are now being submitted to archeogenetic analysis by foreign partners using cutting-edge techniques, which, if successful, could sequence the whole genome of the maize found in Peruaçu Valley and determine its phylogenetic tree with precision.
Peruaçu Valley has some of the very few caves in the world with rock paintings of crops. In addition to being portrayed on the cave walls, maize has been found in buried baskets, probably as an offering to the dead interred there.
The discovery also has geopolitical implications. Once it has been established that domestication of maize races was completed in Brazil, these genetic resources can no longer be considered exotic, requiring conservation efforts and negotiation of property rights in international treaties.
